from Fiona L. Henriquez (University of the West of Scotland, Paisley, UK) writing in Parasites and Vectors (2009) 2: 16

There is an increasing interest and awareness of the free-living amoeba, Acanthamoeba, over recent years as an opportunistic pathogen of medical importance. The publication of this book is a timely reflection of this current situation. The author is to be congratulated on the provision of such a comprehensive review of the literature concerning all aspects of Acanthamoeba research. The intention of the author was to provide an essential reference for researchers of infectious diseases. This is achieved and in addition, this book should also be beneficial to students at the university level with a specific interest in microbiology.

This book is certainly a 'must read' for all scientists interested in medical and environmental microbiology. It is a very convincing overview and foundation of what is already known about Acanthamoeba, but the literature is constantly progressing rapidly and new information is arising about this, until recently, understudied organism.

Further reading: Acanthamoeba: Biology and Pathogenesis

Labels: Acanthamoeba, amoeba, Amoebiasis, book review, books, free-living amoeba, opportunistic pathogen, parasites

Neisseria gonorrhoeae and Neisseria meningitidis are Gram-negative diplococci. Neisseria gonorrhoeae is the causative agent of gonorrhoeae and is transmitted via sexual contact. Neisseria meningitidis is transmitted via respiratory droplets leading to colonization of the nasopharynx and can cause meningitis and septicemia. Diseases caused by Neisseria meningitidis and Neisseria gonorrhoeae, are a significant health problem worldwide.

Analyses of the available genome sequences of Neisseria species and strains have considerably increased our knowledge of the pathogenesis of this genus.

Further reading: Neisseria: Molecular Mechanisms of Pathogenesis

Labels: gonorrhoeae, Gram-negative diplococci, meningitis, Neisseria, Neisseria gonorrhoeae, Neisseria meningitidis, septicemia

Dengue virus (DENV), a mosquito-borne flavivirus, is the causative agent of dengue fever, currently one of the most significant emerging disease challenges to global public health. Although dengue is an old disease, recent decades have seen an unprecedented increase in the geographic range, incidence, and severity of infection. The virus infects 100 million people annually and is endemic in many tropical and sub-tropical regions in the world.

At present, neither a licensed vaccine nor anti-viral drugs are available to control dengue disease, prompting a plethora of research initiatives aimed at understanding the molecular and cellular virology, genomics, and evolution of this important virus.

Further reading: Frontiers in Dengue Virus Research

Labels: dengue, dengue disease, dengue fever, dengue virus, DENV, flavivirus

The aspergilli are a fascinating group of fungi exhibiting immense ecological and metabolic diversity. These include notorious pathogens such as Aspergillus flavus, which produces aflatoxin, one of the most potent, naturally occurring, compounds known to man. Conversely, also included are other fungi, such as A. oryzae, involved in the industrial production of soy sauce and sake or A. niger used for the production of citric acid and enzymes such as glucose oxidase and lysozyme.

Such is the interest in Aspergillus that, to date, the sequences of fifteen different Aspergillus genomes have been determined providing scientists with an exciting resource to improve the understanding of Aspergillus molecular genomics and act as a spring board for mining for new metabolites and novel genes of industrial or medical importance.

Further reading: Aspergillus: Molecular Biology and Genomics

Labels: aflatoxin, aspergilli, aspergillus, Aspergillus flavus, Aspergillus niger, Aspergillus oryzae, fungal, fungi

Molecular biology has revolutionized the study of microorganisms in the environment and improved our understanding of the composition, phylogeny, and physiology of microbial communities. The current molecular toolbox encompasses a range of DNA-based technologies and new methods for the study of RNA and proteins extracted from environmental samples. Currently there is a major emphasis on the application of "omics" approaches to determine the identities and functions of microbes inhabiting different environments.

The molecular tehnologies currently available for the study of the composition and diversity of microbial communities and their functions include metagenomics, metaproteomics, microarrays, and molecular fingerprinting.

Further reading: Environmental Molecular Microbiology

Labels: environment, environmental microbiology, environmental molecular microbiology

ABC transporters are fascinating molecular systems that catalyze the vectorial transport of a great variety of substrates across biological membranes. They constitute a large superfamily of primary active transport systems that are present in all kingdoms of life, and play a diversity of physiological roles.

A prominent characteristic of these systems is that they share a highly conserved domain, the ATP binding cassette (ABC), which binds and hydrolyzes ATP. The amino acid sequence of this cassette displays three major conserved motifs: the Walker A and Walker B motifs commonly found in P-loop containing ATPases or GTPases and a specific signature motif known as the linker peptide, the ABC signature motif, or simply the C loop.

The year 2006 marked the 20th anniversary of the identification of the ABC protein superfamily, and the 30th anniversary of the molecular identification of P-glycoprotein (MDR1, ABCB1). The gene of P-glycoprotein was sequenced in 1986 and it turned out to be the first example of the 48 individual transporters that belong to the ABC protein family in humans.

The cellular physiology of prokaryotes (including cellular processes and their regulation) critically relies on ABC systems. Among prokaryotes, ABC proteins segregate into 29 families belonging to three main functional branches of the ABC system (importers, exporters and "other"). They facilitate the import of essential nutrients and the extrusion of toxins, and participate in DNA repair and translation or regulation of gene expression.

In eukaryotes ABC proteins function only as efflux pumps playing multiple and important physiological roles.

As ABC transporters extrude an unusually large set of chemically diverse compounds, they are implicated in multidrug resistance (MDR) and pleiotropic drug resistance (PDR), and may hinder the clinical treatment of microbial infections and human cancers. However, there is accumulating evidence that MDR transporters also have natural physiological roles.

Alicia Ponte-Sucre (2009) in "ABC Transporters in Microorganisms" Published by Caister Academic Press ISBN 978-1-904455-49-3

Further reading: ABC Transporters

Labels: ABC signature motif, active transport systems, ATP binding cassette, P-loop, superfamily, Walker A motif, Walker B motif

The Type IV pili are architectural marvels of biology. These helical arrays of thousands of copies of a single pilin subunit are extremely thin and flexible yet remarkably strong, and they possess a diverse array of functions. Type IV pili are essential for host colonization and virulence for many Gram negative bacteria, and may also play a role in pathogenesis for some Gram positive bacteria.

High resolution structures of pilin subunits have been determined by X-ray crystallography and nuclear magnetic resonance spectroscopy both as full length proteins and as soluble fragments. These structures have been used to generate computational models of pilus filament assemblies, guided by biophysical parameters extracted from fiber diffraction data and electron microscopy image analysis, and by a dense literature of biological data.

Most recently, cryo-electron microscopy has provided an intermediate resolution structure of a pilus filament. The pilin structures and filament models have been instrumental in advancing our understanding of the molecular mechanisms driving pilus assembly and the role of Type IV pili in key bacterial functions such as immune evasion, microcolony formation and DNA uptake.

In very general terms the structural data point to a shared subunit structure and filament architecture for all Type IV pili, but a comprehensive, atomic-level understanding of these filaments and their biological processes will require additional higher resolution filament structures as well as new structural, genetic and biochemical data on the many components of the pilus assembly apparatus.

from Lisa Craig (2009) in Type IV Pilus Structure Chapter 4 in Jarrell, K. Ed., Pili and Flagella: Current Research and Future Trends ISBN: 978-1-904455-48-6

Further reading: Pili and Flagella

Labels: pili

Flagella-dependent motility is widespread throughout prokaryotes and is advantageous when nutrients are limited, as a mechanism to migrate to more favourable environments and to compete with other microorganisms. Flagella systems can also play an important role in additional processes such as adhesion to substrates, biofilm formation and host invasion in pathogenic bacteria. A variety of different classes of pili are found in prokaryotes and these structures also possess a diverse array of functions. Pili are essential for host colonization, virulence and pathogenesis for many bacteria and, in the case of type IV pili, can also be employed for motility across solid surfaces.

Further reading: Pili and Flagella

Labels: adhesion, biofilms, flagella, motility, pili