Sulphur metabolism in mycobacteria
Sulphur is an essential component of all living cells. The importance of sulphur is well-represented by the sulfhydryl (thiol) functional group, lying at the center of many chemical reactions in biology. Thiol-based reactions have diverse biological functions: thiols in thioredoxins provide reductive power for the synthesis of biological molecules; thiols in coenzyme A facilitate the oxidation of pyruvate and fatty acids to generate energy for living cells; and thiols in glutathione and mycothiol are involved in detoxifying hazardous molecules, as well as maintaining the redox balance of living cells. Additionally, sulphur-containing molecules function as messengers in intracellular and intra-species communation. Sulphur is also a constituent of many other biomolecules like cysteine, methionine, biotin, lipoic acid, molybdopterin, thionucleosides in tRNAs, and thiamine.
Sulphur metabolic pathways of pathogenic bacteria, such as mycobacteria, hold importance both for its biological implications as well as discovering drug targets against enzymes in these pathways. Several enzymes in the sulphur metabolic pathways are essential for mycobacterial survival. The endeavour to map the sulphur metabolic pathways has been greatly facilitated by the emerging information drawn from mycobacterial genome sequencing. Sulphur metabolism plays a role in the pathogenesis of the human pathogen, Mycobacterium tuberculosis, contributing to intracellular survival and virulence. The other mycobacterial species include: Mycobacterium leprae which causes leprosy in humans, Mycobacterium bovis which causes tuberculosis in cattle, Mycobacterium avium which causes disease in immune-compromised individuals, M. bovis Bacille Calmette-Guérin (BCG) which is an attenuated strain of M. bovis used as a vaccine strain and Mycobacterium smegmatis which is a saprophytic non-pathogenic species used extensively as a laboratory model for mycobacterial research.
One-third of the world's population is infected with latent tuberculosis, indicating that the human immune system is capable of controlling the M. tuberculosis infection but not always able to eradicate the bacterium. It has been suggested that sulphur metabolism may have a the role in the prevention of eradication of M. tuberculosis by the human immune system.
from Chapter 7 "Sulphur Metabolism in Mycobacteria" (Ryan H. Senaratne and Kathleen Y. Dunphy) in Mycobacterium: Genomics and Molecular Biology
Further reading: Mycobacterium: Genomics and Molecular Biology
Sulphur metabolic pathways of pathogenic bacteria, such as mycobacteria, hold importance both for its biological implications as well as discovering drug targets against enzymes in these pathways. Several enzymes in the sulphur metabolic pathways are essential for mycobacterial survival. The endeavour to map the sulphur metabolic pathways has been greatly facilitated by the emerging information drawn from mycobacterial genome sequencing. Sulphur metabolism plays a role in the pathogenesis of the human pathogen, Mycobacterium tuberculosis, contributing to intracellular survival and virulence. The other mycobacterial species include: Mycobacterium leprae which causes leprosy in humans, Mycobacterium bovis which causes tuberculosis in cattle, Mycobacterium avium which causes disease in immune-compromised individuals, M. bovis Bacille Calmette-Guérin (BCG) which is an attenuated strain of M. bovis used as a vaccine strain and Mycobacterium smegmatis which is a saprophytic non-pathogenic species used extensively as a laboratory model for mycobacterial research.
One-third of the world's population is infected with latent tuberculosis, indicating that the human immune system is capable of controlling the M. tuberculosis infection but not always able to eradicate the bacterium. It has been suggested that sulphur metabolism may have a the role in the prevention of eradication of M. tuberculosis by the human immune system.
from Chapter 7 "Sulphur Metabolism in Mycobacteria" (Ryan H. Senaratne and Kathleen Y. Dunphy) in Mycobacterium: Genomics and Molecular Biology
Further reading: Mycobacterium: Genomics and Molecular Biology
Labels: mycobacteria, mycobacterium, sulphur, tuberculosis
Lactic Acid Bacteria Conference
The 9th Symposium on Lactic Acid Bacteria (LAB9) will open soon (August 31st) in the Congress Centre “Hotel Zuiderduin”, Zeeweg 52, Egmond aan Zee, the Netherlands. The 9th Symposium programme will involve a limited number of plenary invited lectures covering state-of-the-art developments with attention on Systems Biology, Evolution and Health, as well as a larger number of plenary or parallel short lectures. Besides scientists working on LAB, key note lecturers from outside the LAB field will give stimulatory talks on subjects that are of emerging interest and importance for the LAB. Evening thematic sessions on topics of specific interest will take place.
Poster contributions in all areas of research on Lactic Acid Bacteria, especially also on industrial applications are encouraged. There will be ample time for poster viewing and the posters will be on display during the whole symposium.
Finally, there will be several plenary sessions during which a number of selected posters will be explained briefly.
Further information More microbiology conferences: Microbiology Conference
Further reading: Lactobacillus Molecular Biology: From Genomics to Probiotics
Poster contributions in all areas of research on Lactic Acid Bacteria, especially also on industrial applications are encouraged. There will be ample time for poster viewing and the posters will be on display during the whole symposium.
Finally, there will be several plenary sessions during which a number of selected posters will be explained briefly.
Further information More microbiology conferences: Microbiology Conference
Further reading: Lactobacillus Molecular Biology: From Genomics to Probiotics
Labels: lactic acid bacteria, lactobacillus, probiotics
Spotlight on Xanthomonas
The genus Xanthomonas consists of 20 plant-associated species, many of which cause important diseases of crops and ornamental plants. Individual species comprise multiple pathovars, characterized by distinctive host specificity or mode of infection. Genomics is at the center of a revolution in Xanthomonas biology. Complete genome sequences are available for nine Xanthomonas strains, representing three species and five pathovars, including vascular and non-vascular pathogens of the important models for plant biology, Arabidopsis thaliana and rice. With the diversity of complete and pending Xanthomonas genome sequences, the genus has become a superb model for understanding functional, regulatory, epidemiological, and evolutionary aspects of host- and tissue-specific plant pathogenesis.
Further reading: Damien F. Meyer and Adam J. Bogdanove Chapter 7 in Plant Pathogenic Bacteria
Furthermore, Xanthomonas strains produce the acidic exopolysaccharide xanthan gum. Because of its physical properties, xanthan gum is widely used as a viscosifer, thickener, emulsifier or stabilizer in both food and non-food industries.
Further reading: Anke Becker and Frank-Jörg Vorhölter Chapter 1 in Microbial Production of Biopolymers and Polymer Precursors
Further reading: Damien F. Meyer and Adam J. Bogdanove Chapter 7 in Plant Pathogenic Bacteria
Furthermore, Xanthomonas strains produce the acidic exopolysaccharide xanthan gum. Because of its physical properties, xanthan gum is widely used as a viscosifer, thickener, emulsifier or stabilizer in both food and non-food industries.
Further reading: Anke Becker and Frank-Jörg Vorhölter Chapter 1 in Microbial Production of Biopolymers and Polymer Precursors
Labels: bacteriology, bacterium, biopolymers, biotechnology, xanthan, xanthomonas
Microbiology Conferences and Meetings 2009 - 2010
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Any conference missing from this list? Please send details
Microbiology conferences 2009
August 2009
August 2 - 7, 2009 Periodontal Diseases
New London, NH, USA Further information
Gordon Research Conference. Eight sessions that address current issues in periodontal disease including microbial genomics, virulence attributes of oral microorganisms, bacterial biofilm dynamics, host-microbe recognition, innate immunity, cell signaling, controlling inflammation, cellular control at the epigenetic and microRNA level, antigen presentation and adaptive immunity and systems biology.
Suggested reading: Molecular Oral Microbiology
August 6 - 7, 2009 Lab-on-a-Chip World Congress
South San Francisco, CA, USA Further information
Suggested reading: Lab-on-a-Chip Technology Lab-on-a-Chip Applications
August 6 - 7, 2009 Microarray World Congress
South San Francisco, CA, USA Further information
Suggested reading: Lab-on-a-Chip Technology Real-Time PCR
August 6 - 7, 2009 Molecular Diagnostics World Congress
South San Francisco, CA, USA Further information
Suggested reading: Lab-on-a-Chip Applications Real-Time PCR in Microbiology
August 9 - 14, 2009. 13th International Symposium on Phototrophic Prokaryotes
Montreal, Quebec, Canada Further information
Phylogeny, taxonomy and diversity, ecology, physiology, metabolism and global responses, environmental sensing and signal transduction, bioenergetics, proteins and genomics, bioremediation, secondary metabolites, and applied aspects.
August 16 - 21, 2009 Tuberculosis Drug Development
Oxford, UK Further information
Gordon Research Conference. Targets, Technologies and Trials will cover the range of activities involved in producing new antibiotics. The conference will feature discussion of target and compound discovery, new potential antituberculous compounds in development, clinical trial design and early trial results and alternative approaches to tuberculosis treatment.
Suggested reading: Mycobacterium: Genomics and Molecular Biology
August 26 - 29, 2009. Pasteur's Legacy: Yeast for Health and Biotechnologies (the 27th International Specialised Symposium on Yeast)
Institut Pasteur, Paris, France Further information
August 30 - September 3, 2009. Bacillus-ACT 2009: The International Bacillus anthracis, B. cereus, and B. thuringiensis Conference
Santa Fe, New Mexico Further information
Suggested reading:
Lactobacillus Molecular Biology
Bacillus: Cellular and Molecular Biology
August 30 - September 4, 2009 Staphylococcal Diseases
Waterville Valley, NH, USA Further information
Gordon Research Conference. Cutting-edge research on Staphylococcus aureus and coagulase-negative staphylococcus. The Conference will feature a wide range of topics, including the evolution of antibiotic resistance; exoproteins; the immune response to infection; regulatory control mechanisms; biofilm production and metabolism; therapeutics and vaccines; and animal models and virulence. Invited speakers include representatives from both academic and industrial settings who are at the forefront of their field.
Suggested reading: Staphylococcus: Molecular Genetics
September 2009
September 1 - 4, 2009. British Mycological Society annual scientific meeting
Dundee, UK Further information
The Fungal Cell. Including cellular organisation, metabolism and cellular regulation, fungal growth, morphogenesis and differentiation, and fungal interactions with other organisms including bacteria and plants.
Suggested reading: Mycology Books
September 2 - 5, 2009. EuroBiofilms2009 1st European Congress on Microbial Biofilms
Rome, Italy Further information
September 6 - 11, 2009 Malaria
Oxford, UK Further information
Gordon Research Conference. Parasite Biology and Host-Parasite Interactions. This meeting will focus on basic biology of malaria parasites, their interaction with the host and vector, malaria immunology and molecular basis of pathogenic mechanisms in malaria. The latest results from genetic, biochemical and molecular approaches to understand malaria parasite biology and disease mechanisms in malaria will be presented. The application of such new knowledge to the development of novel intervention strategies including drugs and vaccines against malaria will also be covered.
Suggested reading: Malaria Parasites: Genomes and Molecular Biology
September 7 - 10, 2009. SGM Autumn 2009 Meeting
Heriot-Watt University, Edinburgh Further information
Suggested reading: Microbiology Books
September 9, 2009 Advances in BioDetection Technologies
London, UK Further information
Select Biosciences Conference
September 9 - 12, 2009. 5th Orthomyxovirus Research Conference
Freiburg, Germany Further information
September 17 - 18, 2009. Control and Management of Pathogenic Escherichia coli
Dublin, Ireland Further information
Pathogenic Escherichia coli Network International Conference.
September 17 - 18, 2009 Advances in qPCR
Berlin, Germany Further information
Suggested reading: Real-Time PCR in Microbiology
September 20 - 23, 2009 61st Annual Meeting of the German Society for Hygiene and Microbiology (DGHM)
Georg-August-University, Goettingen, Germany Further information
A platform for profound discussions on current topics of medical microbiology, immunology, virology, parasitology and hygiene.
September 21 - 23, 2009 Frontiers of Retrovirology: complex retroviruses, retroelements and their hosts
Montpellier, France Further information
This conference will bring together leading human retrovirus researchers to review current progress and to chart future challenges. Internationally renowned speakers will present their insights into the principles guiding the life cycle of endogenous retroelements, complex human retroviruses, and their pathogenic interactions with the hosts. Cutting edge presentations will be delivered by internationally renowned researchers. Short oral platform presentations and posters will be selected from registrants. A limited number of scholarships will be available.
Suggested reading: Virology Books
September 22 - 25, 2009. ASM-ESCMID Conference on MRSA in Animals: Veterinary and Public Health Implications
UK Further information
September 22 - 27, 2009. XXIst Conference on Phage/Virus Assembly
Fondation Merieux, Centre les Pensieres, Annecy, France Further information
September 26 - 29, 2009. Central European Symposium on Antimicrobial Resistance (CESAR2009)
Zadar, Croatia Further information
October 2009
October 5 - 9, 2009. 3rd ASM Conference on Salmonella: Biology, Pathogenesis & Prevention
Aix-en-Provence, France Further information
Suggested reading: Foodborne Pathogens: Microbiology and Molecular Biology
October 13 - 17, 2009. Legionella 2009
Paris, France Further information
The 7th International Conference in this series, Legionella 2009, will address a wide range of current research and trends related to Legionella. Sessions will be dedicated to epidemiology and clinical aspects; pathogenesis and immunology; genetics and genomics; ecology and evolution; physiology, regulation, and biochemistry.
Suggested reading: Legionella: Molecular Microbiology
October 18 - 21, 2009. 4th Trends in Medical Mycology TIMM4
Athens, Greece Further information
Organized jointly by the European Confederation of Medical Mycology (ECMM) and by the Infectious Diseases Group of the European Organization for Research and Treatment of Cancer (IDG-EORTC). The scientific programme will include plenary sessions on fungal infections in both immunocompromised and immunocompetent hosts led by an internationally renowned faculty giving plenary talks, round table sessions, and meet-the-expert meetings. The poster session will encourage one-to-one discussions between faculty, presenters and delegates. The meeting is designed for infectious disease specialists, haematologists, oncologists, transplant physicians, microbiologists, immunologists, dermatologists, intensivists and others with interest in medical mycology.
Suggested reading: Mycology Books
October 22 - 23, 2009. European Meeting on Molecular Diagnostics
Scheveningen, The Hague, Netherlands Further information
The sixth in a series of meetings, devoted to all aspects of molecular diagnostics in disease and pathology of humans. The Scheveningen Meeting is organised every two years. The scope of the meeting has expanded to include other amplification techniques, general probe technology and more laboratory disciplines. The emphasis of the meetings will continue to be on novel technology and its consequences for (new) clinical molecular diagnostics. The format of the meetings includes general, introductory lectures by internationally renowned experts in combination with free presentations in dedicated workshops, poster session and industrial exhibits.
Suggested reading: Real-Time PCR in Microbiology
October 29 - 31, 2009. Mycology MasterClass IV
Hamilton Island, QLD, Australia Further information
Advanced medical mycology course for specialists and trainees in infectious diseases, microbiology, haematology and intensive care medicine and for laboratory scientists/technicians specialising in medical mycology.
Suggested reading: Pathogenic Fungi: Insights in Molecular Biology
November 2009
November 8 - 11, 2009. Recent Advances in Fermentation Technology (RAFT)
San Diego, CA Further information
November 15 - 19, 2009. 5th ASM Conference on Biofilms
Cancun, Mexico Further information
Suggested reading: Molecular Oral Microbiology
December 2009
Microbiology conferences 2010
Any conference missing from this list? Please send details
March 2010
March 22 - 26, 2010 10th ASM Conference on Candida and Candidiasis
Miami, USA Further information
Suggested reading: Candida: Comparative and Functional Genomics
March 22 - 26, 2010 2nd ASM Conference on Dimorphic Fungal Pathogens
Miami, USA Further information
Suggested reading: Fungal Books
April 2010
April 24 - 28, 2010 2nd ASM Conference on Mobile DNA
Montreal, Canada Further information
Suggested reading: Molecular Biology Books
May 2010
May 5 - 8, 2010 ISOPOL XVII - International Symposium On Problems Of Listeriosis
Porto, Portugal Further information
ISOPOL XVII will bring together specialists from a wide range of scientific disciplines from all over the world (from Vets, Medics, Bioscientists to Public-Health and Food Industry specialists, from junior researchers to world-leaders in their fields) to discuss the most important and up to date issues concerning Listeria and Listeriosis.
Suggested reading: Bacteriology Books
June 2010
June, 2010 2nd ASM Conference on Antimicrobial Resistance in Zoonootic Bacteria and Foodborne Pathogens
Toronto, Canada Further information
Suggested reading: Foodborne Pathogens: Microbiology and Molecular Biology
June 28 - July 1, 2010. GIM 2010. The 11th International Symposium on the Genetics of Industrial Microorganisms
Melbourne, Victoria, Australia Further information
GIM is a meeting that occurs once every four years and this will be the first time GIM has been held in Australia. Of interest to academics; agricultural specialists; beer, wine and sake researchers; food/information/energy technologists; fuel industry; government policy makers; health specialists; molecular biologists; pharmaceutical industry; students with an interest/involvement in the impact microbes can make to our future health and well being.
July 2010
July 30 - August 2, 2010 3rd ASM Conference on Enterococci
Portland, USA Further information
Suggested reading: Bacteriology Books
September 2010
September 1 - 3, 2010 Biofilms4 International Conference
Winchester, UK Further information
The fourth International Biofilms Conference
Suggested reading: Microbiology Books
September 26 - 30, 2010 2nd ASMET - The ASM Emerging Technologies Conference
Cancun, Mexico Further information
Suggested reading: Molecular Biology Books
October 2010
October 25 - 29, 2010 3rd ASM Conference on Beneficial Microbes
Miami, USA Further information
Suggested reading: Probiotics Books
Labels: microbiology conference, microbiology meeting, virology conference, virology meeting
Exopolysaccharides
Microorganisms synthesize a wide spectrum of exopolysaccharides many of which have important applications in biotechnology and the food imdustry. Exopolysaccharides produced by microorganisms include:
acetan (Acetobacter xylinum) alginate (Azotobacter vinelandii) cellulose (Acetobacter xylinum) chitosan (Mucorales spp.) curdlan (Alcaligenes faecalis var. myxogenes) cyclosophorans (Agrobacterium spp., Rhizobium spp. and Xanthomonas spp.) dextran (Leuconostoc mesenteroides, Leuconostoc dextranicum and Lactobacillus hilgardii) emulsan (Acinetobacter calcoaceticus) galactoglucopolysaccharides (Achromobacter spp., Agrobacterium radiobacter, Pseudomonas marginalis, Rhizobium spp. and Zooglea spp.) gellan (Aureomonas elodea and Sphingomonas paucimobilis) glucuronan (Rhizobium meliloti) N-acetyl-heparosan (Escherichia coli) hyaluronic acid (Streptococcus equi) indican (Beijerinckia indica) kefiran (Lactobacillus hilgardii) lentinan (Lentinus elodes) Levan polysaccharide|levan (Alcaligenes viscosus, Zymomonas mobilis) pullulan (Aureobasidium pullulans) scleroglucan (Sclerotium rolfsii, Sclerotium delfinii and Sclerotium glucanicum) schizophyllan (Schizophylum commune) succinoglycan (Alcaligenes faecalis var myxogenes) xanthan (Xanthomonas campestris) welan (Alcaligenes spp.)
Anita Suresh Kumar and Kalpana Mody from Chapter 10 in Microbial Production of Biopolymers and Polymer Precursors
Further reading: Microbial Production of Biopolymers and Polymer Precursors
Anita Suresh Kumar and Kalpana Mody from Chapter 10 in Microbial Production of Biopolymers and Polymer Precursors
Further reading: Microbial Production of Biopolymers and Polymer Precursors
Labels: bacterium, exopolysaccharides, lactic acid bacteria
Bacterial Cellulose
Many bacteria possess the genes needed to produce cellulose. However, Gluconacetobacter xylinus (formerly Acetobacter xylinum) is used for studies of the biochemistry and genetics of cellulose biosynthesis. Structurally cellulose is a simple polysaccharide, in that it consists only of one type of sugar (glucose), and the units are linearly arranged and linked together by β-1,4 linkages only. The mechanism of biosynthesis is however rather complex, partly because in native celluloses the chains are organized as highly ordered water-insoluble fibers. Currently the key genes involved in cellulose biosynthesis and regulation are known in a number of bacteria, but many details of the biochemistry of its biosynthesis are still not clear. A survey of genome sequence databases clearly indicates that a very large number of bacteria have the genes needed to produce cellulose, and this has also been experimentally confirmed for a smaller number of organisms. The biological functions of bacterial celluloses vary among species, and range from a role as a floating device to involvement in plant root adhesion and biofilm formation.
Valla et al from Chapter 3 in Microbial Production of Biopolymers and Polymer Precursors
Further reading: Microbial Production of Biopolymers and Polymer Precursors
Valla et al from Chapter 3 in Microbial Production of Biopolymers and Polymer Precursors
Further reading: Microbial Production of Biopolymers and Polymer Precursors
Labels: bacterium, biopolymers, biotechnology, cellulose
Diagnosis and treatment of Legionnaires disease
The methods currently available to diagnose Legionnaires' disase are culture, urinary antigen detection, direct fluorescent antibody testing, detection of nucleic acid and detection of specific antibodies in serum samples. Presently, none of the diagnostic tests available offers the desired quality with respect to sensitivity and specificity. Culture should be obligatory, especially when hospitalized patients with underlying diseases are investigated. A positive culture is the prerequisite of molecular epidemiological investigations. Urinary antigen detection is a valuable tool in the majority of community-acquired cases when L. pneumophila serogroup 1 is the causative agent. In cases of nosocomial disease, when Legionella pneumophila serogroups other than sg 1 are frequent, this assay has limitations. The detection of nucleic acid is very useful method of diagnosis but requires further validation. The detection of antibodies in a patient's serum is of little use in the acute phase of the illness. Several molecular subtyping techniques are in use to subtype L. pneumophila strains in epidemiological investigations. Legionella pneumophila is genetically very heterogeneous thus allowing an individual fingerprint of each strain. However, the majority of clinical cases are caused by a limited number of clones that cause disease worldwide. The therapy for Legionnaires' disease requires drugs that can access and are active intracellularly. Currently, fluorochinolones and macrolides are the most active agents.
Further reading: Paul C. Lück in Legionella: Molecular Microbiology
Further reading: Paul C. Lück in Legionella: Molecular Microbiology
Labels: bacteriology, bacterium, legionella
Regulation of Gene Expression
RNA and the Regulation of Gene Expression
"This book is a well-selected compilation of 14 mostly review-style articles, written by experts in the field ... a well-written, successful endeavour to present the field of eukaryal RNA-mediated regulation of gene expression. It has its major strength in providing an extremely well structured, up-to-date, comprehensive overview that skillfully zooms the reader into each topic from a general introduction to a high degree of detail ... suited for a broad range of readers, from advanced students to researchers in the field. Personally, we very much enjoyed reading it."
from D. K. Willkomm and R. K. Hartmann, Universitat Marburg, Germany in ChemBioChem (2008) 9: 2005-2007
Further reading: RNA and the Regulation of Gene Expression
Edited by: Kevin V. Morris. ISBN: 978-1-904455-25-7
"This book is a well-selected compilation of 14 mostly review-style articles, written by experts in the field ... a well-written, successful endeavour to present the field of eukaryal RNA-mediated regulation of gene expression. It has its major strength in providing an extremely well structured, up-to-date, comprehensive overview that skillfully zooms the reader into each topic from a general introduction to a high degree of detail ... suited for a broad range of readers, from advanced students to researchers in the field. Personally, we very much enjoyed reading it."
from D. K. Willkomm and R. K. Hartmann, Universitat Marburg, Germany in ChemBioChem (2008) 9: 2005-2007
Further reading: RNA and the Regulation of Gene Expression
Edited by: Kevin V. Morris. ISBN: 978-1-904455-25-7
Labels: book review, rna
Clostridial toxins
The genus Clostridium represents a heterogeneous group of toxin-producing species, such as C. difficile, C. botulinum, C. tetani and C. perfringens. C. tetani and C. botulinum produce the most potent biological toxins known to affect humans. Further reading: Clostridia: Molecular Biology in the Post-genomic Era
Botulinum and Tetanus Neurotoxins
Botulinum neurotoxins (BoNT) and tetanus toxin (TeNT) are potent toxins which are responsible for severe diseases, botulism and tetanus, in men and animals. BoNTs induce a flaccid paralysis, whereas TeNT causes a spastic paralysis. Both toxins are zinc-dependent metalloproteases, which specifically cleave one of the three proteins (VAMP, SNAP25, and syntaxin) forming the SNARE complex within target neuronal cells which have a critical function in the release of neurotransmitter. BoNTs inhibit the release of acetylcholine at peripheral cholinergic nerve terminals, whereas TeNT blocks neurotransmitter release at central inhibitory interneurons. Only a single form of TeNT is known, but BoNTs are divided in 7 toxinotypes and various subtypes, which differ in amino acid sequences and immunological properties. In contrast to TeNT, BoNTs are associated to non-toxic proteins (ANTPs) to form highly stable botulinum complexes. TeNT is produced by Clostridium tetani, and BoNTs by Clostridium botulinum and atypical strains of Clostridium barati and Clostridium butyricum. The genes encoding the neurotoxin and ANTPs are clustered in a DNA segment, called botulinum locus, which is located on chromosome, plasmid or phage. Neurotoxin synthesis is a highly regulated process, which occurs in late exponential growth phase and beginning of stationary phase, and which is dependent of alternative sigma factors (BotR or TetR). BotR and TetR are related to other clostridial sigma factors, TcdR and UviA, which are involved in the control of Clostridium difficile toxins A and B, and Clostridium perfringens bacteriocin, respectively. BotR, TetR, TcdR and UviA form a new subgroup of RNA polymerase sigma factors.
Clostridium perfringens Enterotoxin
Clostridium perfringens enterotoxin (CPE) causes the intestinal symptoms of a common food-borne illness and ~5-15% of all antibiotic-associated diarrhea cases. In food poisoning isolates, the enterotoxin gene (cpe) is usually present on the chromosome, while cpe is carried by conjugative plasmids in antibiotic-associated diarrhea isolates. CPE action involves its binding to claudin receptors, oligomerization/prepore formation, and prepore insertion to form a functional pore that kills cells by apoptosis or oncosis. The C-terminal half of CPE mediates receptor binding, while its N-terminal half is required for oligomerization. CPE/CPE derivatives are being explored for cancer therapy/diagnosis and improved drug delivery.
The Cholesterol-dependent Cytolysins and Clostridium septicum α-Toxin
Two classes of pore-forming toxins of the clostridia are represented by the cholesterol-dependent cytolysins (CDCs) and the Clostridium septicum α-toxin. The CDCs are found in a wide variety of clostridial species, but are also found in many species from other Gram-positive genera. As a result, various CDCs have evolved specific traits that appear to enhance their ability to complement the pathogenic mechanism of a specific bacterial species. In contrast, closely related toxins to C. septicum α-toxin (AT) have not been found in other species of the clostridia, although C. perfringens epsilon toxin appears to be distantly related. Remarkably, distant relatives of AT have been found in species of Gram-negative bacteria as well as certain species of mushrooms and the enterolobin tree seed. Although the CDCs appear to be restricted to Gram-positive bacterial pathogens it has recently been shown that the unusual protein fold of their membrane-penetrating domain is present in proteins of the eukaryotic complement membrane attack complex. Both toxins penetrate the membrane by the use of a β-barrel pore but differ significantly in their pore-forming mechanisms.
Binary Bacterial Toxins
Several proteins from Gram-positive, spore-forming bacilli use a synergistic binary mechanism for intoxicating eukaryotic cells. These toxins include Clostridium botulinum C2 toxin, Clostridium difficile toxin (CDT), Clostridium perfringens iota (ι) toxin, and Clostridium spiroforme toxin (CST). Each of these clostridial binary toxins consists of distinct enzymatic "A" and binding "B" proteins that work in concert. Conservation of a basic intoxication theme between different genera clearly suggests retention of an evolutionarily successful mechanism promoting bacterial survival and dissemination.
Group I and II Clostridium botulinum
Clostridium botulinum, producing highly potent botulinum neurotoxin, is a diverse species consisting of four genetically and physiologically distinct groups (Groups I-IV) of organisms. Groups I and II C. botulinum produce A, B, E, and/or F toxins which cause human botulism. In addition, some strains of Clostridium butyricum and Clostridium barati produce type E and F toxins, respectively, and have thus been related to human illness. Human botulism appears in five different forms, such as the classical food botulism, infant botulism, wound botulism, adult infectious botulism, and iatrogenic botulism. Typical of all forms of human botulism is descending flaccid paralysis which may lead to death upon respiratory muscle failure.
C. difficile large clostridial toxins
Clostridium difficile is a toxin producing microorganism and the toxins are the main virulence factors. Two large toxins are produced by the bacterium and epidemiological studies have indicated that strains either produce both toxins (toxin A, TcdA, and toxin B, TcdB) or none of them. Toxigenic strains are usualy associated with the disease, while nontoxigenic are not. Strains producing only TcdB or strains producing an additional toxin (binary toxin CDT) have been described. Such strains with unusual toxin production pattern have changes in the genomic PaLoc region encoding the toxins TcdA and TcdB. These changes are the basis for a method that distinguish C. difficile strains into toxinotypes.
Further reading: Clostridia: Molecular Biology in the Post-genomic Era
Botulinum and Tetanus Neurotoxins
Botulinum neurotoxins (BoNT) and tetanus toxin (TeNT) are potent toxins which are responsible for severe diseases, botulism and tetanus, in men and animals. BoNTs induce a flaccid paralysis, whereas TeNT causes a spastic paralysis. Both toxins are zinc-dependent metalloproteases, which specifically cleave one of the three proteins (VAMP, SNAP25, and syntaxin) forming the SNARE complex within target neuronal cells which have a critical function in the release of neurotransmitter. BoNTs inhibit the release of acetylcholine at peripheral cholinergic nerve terminals, whereas TeNT blocks neurotransmitter release at central inhibitory interneurons. Only a single form of TeNT is known, but BoNTs are divided in 7 toxinotypes and various subtypes, which differ in amino acid sequences and immunological properties. In contrast to TeNT, BoNTs are associated to non-toxic proteins (ANTPs) to form highly stable botulinum complexes. TeNT is produced by Clostridium tetani, and BoNTs by Clostridium botulinum and atypical strains of Clostridium barati and Clostridium butyricum. The genes encoding the neurotoxin and ANTPs are clustered in a DNA segment, called botulinum locus, which is located on chromosome, plasmid or phage. Neurotoxin synthesis is a highly regulated process, which occurs in late exponential growth phase and beginning of stationary phase, and which is dependent of alternative sigma factors (BotR or TetR). BotR and TetR are related to other clostridial sigma factors, TcdR and UviA, which are involved in the control of Clostridium difficile toxins A and B, and Clostridium perfringens bacteriocin, respectively. BotR, TetR, TcdR and UviA form a new subgroup of RNA polymerase sigma factors.
Clostridium perfringens Enterotoxin
Clostridium perfringens enterotoxin (CPE) causes the intestinal symptoms of a common food-borne illness and ~5-15% of all antibiotic-associated diarrhea cases. In food poisoning isolates, the enterotoxin gene (cpe) is usually present on the chromosome, while cpe is carried by conjugative plasmids in antibiotic-associated diarrhea isolates. CPE action involves its binding to claudin receptors, oligomerization/prepore formation, and prepore insertion to form a functional pore that kills cells by apoptosis or oncosis. The C-terminal half of CPE mediates receptor binding, while its N-terminal half is required for oligomerization. CPE/CPE derivatives are being explored for cancer therapy/diagnosis and improved drug delivery.
The Cholesterol-dependent Cytolysins and Clostridium septicum α-Toxin
Two classes of pore-forming toxins of the clostridia are represented by the cholesterol-dependent cytolysins (CDCs) and the Clostridium septicum α-toxin. The CDCs are found in a wide variety of clostridial species, but are also found in many species from other Gram-positive genera. As a result, various CDCs have evolved specific traits that appear to enhance their ability to complement the pathogenic mechanism of a specific bacterial species. In contrast, closely related toxins to C. septicum α-toxin (AT) have not been found in other species of the clostridia, although C. perfringens epsilon toxin appears to be distantly related. Remarkably, distant relatives of AT have been found in species of Gram-negative bacteria as well as certain species of mushrooms and the enterolobin tree seed. Although the CDCs appear to be restricted to Gram-positive bacterial pathogens it has recently been shown that the unusual protein fold of their membrane-penetrating domain is present in proteins of the eukaryotic complement membrane attack complex. Both toxins penetrate the membrane by the use of a β-barrel pore but differ significantly in their pore-forming mechanisms.
Binary Bacterial Toxins
Several proteins from Gram-positive, spore-forming bacilli use a synergistic binary mechanism for intoxicating eukaryotic cells. These toxins include Clostridium botulinum C2 toxin, Clostridium difficile toxin (CDT), Clostridium perfringens iota (ι) toxin, and Clostridium spiroforme toxin (CST). Each of these clostridial binary toxins consists of distinct enzymatic "A" and binding "B" proteins that work in concert. Conservation of a basic intoxication theme between different genera clearly suggests retention of an evolutionarily successful mechanism promoting bacterial survival and dissemination.
Group I and II Clostridium botulinum
Clostridium botulinum, producing highly potent botulinum neurotoxin, is a diverse species consisting of four genetically and physiologically distinct groups (Groups I-IV) of organisms. Groups I and II C. botulinum produce A, B, E, and/or F toxins which cause human botulism. In addition, some strains of Clostridium butyricum and Clostridium barati produce type E and F toxins, respectively, and have thus been related to human illness. Human botulism appears in five different forms, such as the classical food botulism, infant botulism, wound botulism, adult infectious botulism, and iatrogenic botulism. Typical of all forms of human botulism is descending flaccid paralysis which may lead to death upon respiratory muscle failure.
C. difficile large clostridial toxins
Clostridium difficile is a toxin producing microorganism and the toxins are the main virulence factors. Two large toxins are produced by the bacterium and epidemiological studies have indicated that strains either produce both toxins (toxin A, TcdA, and toxin B, TcdB) or none of them. Toxigenic strains are usualy associated with the disease, while nontoxigenic are not. Strains producing only TcdB or strains producing an additional toxin (binary toxin CDT) have been described. Such strains with unusual toxin production pattern have changes in the genomic PaLoc region encoding the toxins TcdA and TcdB. These changes are the basis for a method that distinguish C. difficile strains into toxinotypes.
Further reading: Clostridia: Molecular Biology in the Post-genomic Era
Labels: botulism, clostridia, clostridium, tetanus, toxin
Clostridia in Anti-tumor Therapy
Recent research suggests that Clostridium-based tumor targeted therapy holds promise for the treatment of solid tumors. Upon systemic administration, various strains of non-pathogenic clostridia have been shown to infiltrate and selectively replicate within solid tumors. This specificity is based upon the unique physiology of solid tumors, which is often characterized by regions of hypoxia and necrosis. Clostridial vectors can be safely administered and their potential to deliver therapeutic proteins has been demonstrated in a variety of preclinical models.
from Asferd Mengesha, Ludwig Dubois, Kim Paesmans, Brad Wouters, Philippe Lambin and Jan Theys in Clostridia: Molecular Biology in the Post-genomic Era
Further reading: Clostridia: Molecular Biology in the Post-genomic Era
from Asferd Mengesha, Ludwig Dubois, Kim Paesmans, Brad Wouters, Philippe Lambin and Jan Theys in Clostridia: Molecular Biology in the Post-genomic Era
Further reading: Clostridia: Molecular Biology in the Post-genomic Era
Labels: bacteriology, bacterium, clostridia, clostridium, therapy, tumor
Pathogenic Fungi book review
Writing in the journal Expert Review of Anti-infective Therapy, Steven Bates of the University of Exeter, UK, reviews a new book on Pathogenic Fungi published by Caister Academic Press. His comments include:
"The book Pathogenic Fungi: Insights in Molecular Biology, edited by Gioconda San-Blas and Richard A. Calderone, is a natural extension of the two volume set previously published in 2004 (Pathogenic Fungi: Structural Biology and Taxonomy, and Host Interactions and Emerging Strategies of Control). The current volume extends on the previous two by detailing some of the major advances that have been made in recent years through the application of 'omics' technologies and the generation of new molecular tools. The application of these technologies has resulted in a significant increase in the published research on pathogenic fungi, and this book provides a timely survey of key topics that have been advanced through their use ... The book clearly meets the stated aim of the editors 'to help the busy research scientist and/or teacher of medical mycology to keep abreast of all the latest advances'. Overall the book provides essential reading covering the recent advances, utilising molecular biology approaches, to further our understanding of fungal pathogens of humans. Despite the high price it would be a valuable addition to collections, and recommended reading for those with an interest in the molecular biology of human pathogenic fungi."
For full details please visit Pathogenic Fungi: Insights in Molecular Biology
"The book Pathogenic Fungi: Insights in Molecular Biology, edited by Gioconda San-Blas and Richard A. Calderone, is a natural extension of the two volume set previously published in 2004 (Pathogenic Fungi: Structural Biology and Taxonomy, and Host Interactions and Emerging Strategies of Control). The current volume extends on the previous two by detailing some of the major advances that have been made in recent years through the application of 'omics' technologies and the generation of new molecular tools. The application of these technologies has resulted in a significant increase in the published research on pathogenic fungi, and this book provides a timely survey of key topics that have been advanced through their use ... The book clearly meets the stated aim of the editors 'to help the busy research scientist and/or teacher of medical mycology to keep abreast of all the latest advances'. Overall the book provides essential reading covering the recent advances, utilising molecular biology approaches, to further our understanding of fungal pathogens of humans. Despite the high price it would be a valuable addition to collections, and recommended reading for those with an interest in the molecular biology of human pathogenic fungi."
For full details please visit Pathogenic Fungi: Insights in Molecular Biology
Labels: book review, fungi