The Cell Biology of Cyanobacteria | Book
Caister Academic Press
Enrique Flores and Antonia Herrero Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, E-41092 Seville, Spain
May 2014Buy hardback
GB £159 or US $319
GB £159 or US $319
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The cyanobacteria are a fascinating group of bacteria that have adapted to colonise almost every environment on our planet. They are the only prokaryotes capable of oxygenic photosynthesis, responsible for up to 20-30% of Earth's photosynthetic productivity. They can attune their light-harvesting systems to changes in available light conditions, fix nitrogen and have circadian rhythms. In addition many cyanobacteria species exhibit gliding mobility and can differentiate into specialized cell types called heterocysts, and some are symbiotic. Thanks to their simple nutritional requirements, their metabolic plasticity, and the powerful genetics of some model strains, cyanobacteria could be exploited for use as microbial cell factories for carbon capture and storage, and for the sustainable production of secondary metabolites and biofuels. Understanding their cell biology is an essential step to achieving this.
In this book, leading senior scientists and young researchers review the current key topics in cyanobacterial cell biology to provide a timely overview. Topics covered include: historical background; cell division; the cell envelope; the thylakoid membrane; protein targeting, transport and translocation; chromatic acclimation; the carboxysome; glycogen as a dynamic storage of photosynthetically fixed carbon; cyanophycin; gas vesicles; motility in unicellular and filamentous cyanobacteria; cellular differentiation in filamentous cyanobacteria; and cell-cell joining proteins in heterocyst-forming cyanobacteria. This cutting-edge text will provide a valuable resource for all those working in this field and is recommended for all microbiology libraries.
A Brief History of Cyanobacterial Research: Past, Present, and Future Prospects
Donald A. Bryant
There is no Abstract for this chapter. The text below is the first paragraph of the Introduction. When Antonia and Enrique invited me to write an introductory chapter for their latest book summarizing recent research on cyanobacteria, I thought that it would be a simple task. However, as I thought about it more and more, and as is typical for me procrastinated longer and longer, I became ever more blocked as I looked backward and as time marched forward. Approaches to this chapter seemed either to require too much detail or too little, or so it seemed to me. One would think that after forty years, one might actually have found something worthwhile to say. Yikes!! Forty years! It has now been forty years since I started my long affair with cyanobacteria and research during my first rotation project as a graduate student at UCLA so many years ago in September 1972. Clearly, I believe that it has been a long but very exciting journey. No doubt about it, though: forty years is a long time to do any one thing, and still love it! I finally decided to write just a few brief overview comments concerning my perceptions about this field of science and those, including myself, who have tried in recent years to summarize the collective progress in monographs. So, especially for you newcomers to this field, this will be my limited attempt to describe where this field started, where I started, where the research focus has been recently, and where it might be going for the next 10 years. If one should be so inclined, it also provides a pathway to obtain a historical perspective on the field, especially over the last 60 years.
Cell Division in Cyanobacteria
Corinne Cassier-Chauvat and Franck Chauvat
This review summarizes what is known regarding cell division in cyanobacteria, the fascinating microorganisms that are logically attracting a growing attention in various areas of basic and applied researches. Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, colonize most water and soil environments of our planet, and provide a large part of the oxygenic atmosphere and biomass for the food chain. They display different morphologies ranging from unicellular (cylindrical, spherical and spirals) to complex multi-cellular (filamentous) forms that contain differentiated cells allowing the growth or survival of these organisms under adverse conditions. Furthermore, cyanobacteria divide in one or several successive planes, at right angles or in irregular planes so that the cells may appear singly or in aggregates of varying size. Nowadays, cyanobacteria are regarded as promising “low-cost” microbial cell factories for carbon capture and storage, and for the sustainable production of secondary metabolites and biofuels, thanks to their simple nutritional requirements, their metabolic plasticity, and the powerful genetics of some model strains. In this chapter, we report that cyanobacteria (which are Gram negative) share cytokinetic genes in common with both Gram positive and Gram negative bacteria, and/or the chloroplast and the nuclear genome of plants and algae. In agreement with cyanobacteria being regarded as the ancestor of the chloroplast, the stromal portion of the chloroplast division complex resemble the cyanobacterial cell division machinery, but many other components were lost after the endosymbiotic event.
The Cell Envelope
Alexander Hahn and Enrico Schleiff
Cyanobacteria are prokaryotes with cell envelopes typical for Gram-negative bacteria. The cell envelope consists of four distinct layers, the plasma membrane, the peptidoglycan layer, the outer membrane and in some cases the surface or S-layer. Often, the latter three are referred to as the cell wall. The functionality of the cell envelope is defined by the cooperative action of lipids and membrane-embedded proteins. The membranes of cyanobacterial species contain two types of lipids, phosphoglycerolipids and galactolipids. The proteins of the plasma membrane show the typical α-helix based membrane domain architecture, whereas the proteins in the outer membrane have a β-barrel shaped membrane domain. The proteins perform many distinct functions ranging from solute transport to signal transduction. Thus, several features are indeed comparable between the cyanobacterial and the proteobacterial systems investigated so far. However, some properties are unique for the cyanobacterial branch. In this chapter, we summarize the current knowledge on composition, structure and function of the cell envelope including information obtained from different cyanobacterial strains. We also compare the properties of the cyanobacterial envelope to those of non-photosynthetic Gram-negative bacteria.
Proteomics in Revealing the Composition, Acclimation and Biogenesis of Thylakoid Membranes
Natalia Battchikova and Eva-Mari Aro
Oxygenic photosynthesis evolved in the thylakoid membrane of ancient cyanobacteria. Here we review, from the proteomics viewpoint, the composition and biogenesis of the present day cyanobacteria thylakoid membranes, with main emphasis on the macromolecular protein complexes involved in photosynthetic electron transfer. Response of the thylakoid membrane proteome to changes in environmental cues and to various stress conditions is also described and discussed in terms of dynamic modifications in metabolic and catabolic pathways in order to adjust cyanobacterial cells to a new environment.
Protein Targeting, Transport and Translocation in Cyanobacteria
In contrast to other bacteria, cyanobacterial cells are composed of six different subcellular compartments, and proteins might be localized in one of the three membrane systems (outer, cytoplasmic or thylakoid membrane) or within one of the three soluble compartments, i.e. the periplasmic space, the cytoplasm or the thylakoid lumen. As cyanobacterial cells appear to have distinct sets of proteins localized only in a single subcellular compartment, these organisms eventually have evolved mechanisms to localize proteins to specific membranes for membrane integration or for translocation across these membranes. In the present article we summarize findings on the membrane structure of cyanobacterial cells as well as on heterogeneous protein distribution, and we discuss current models aiming at explaining mechanisms involved in protein targeting and sorting in cyanobacteria.
Chromatic Acclimation: A Many-Coloured Mechanism For Maximizing Photosynthetic Light Harvesting Efficiency
Adam N. Bussell and David M. Kehoe
Our understanding of chromatic acclimation, during which the light harvesting antennae or phycobilisomes of cyanobacteria are modified to optimized to maximize photon capture for photosynthesis, has grown remarkably over the past century. Originally a curiosity of a "chameleon cyanobacteria" capable of dramatically altering its pigmentation between red and green in response to changes in the ambient light color, multiple forms of chromatic acclimation are now known to exist and are found in a wide range of species in most habitats on Earth. This ecologically important process gives species that possess it a fitness advantage in environments with fluctuating light color conditions. The form of chromatic acclimation found in deeper marine environments is sensitive to blue and green light and involves the selective substitution of light-absorbing chromophores for these specific wavelengths, while other types of chromatic acclimation are maximally sensitive to the green and red regions of the visible spectrum and involve the reversible replacement of both proteins and chromophores within the phycobilisomes as well as changes in many other cellular processes. Although some progress has been made in unraveling the mechanisms by which these organisms sense and respond to changes in light color conditions, many questions remain to be answered.
The Carboxysome: Function, Structure and Cellular Dynamics
Jeffrey C. Cameron, Markus Sutter and Cheryl A. Kerfeld
The ability to use light energy for the accumulation and fixation of CO2 has given cyanobacteria the ability to thrive in diverse and extreme environments. Cyanobacteria play a central role in the global carbon cycle and have changed the earth’s atmosphere by generating oxygen and depleting CO2. The CO2 concentrating mechanism (CCM) consists of active transport systems for inorganic carbon acquisition and a distinctive protein-based organelle, the carboxysome. Recent advances in structural and systems biology and biological imaging have built upon decades of biochemical and genetic research to advance our understanding of the carboxysome. In this chapter we provide an overview of the carboxysome structure and place the carboxysome in the context of cyanobacterial metabolism and morphology.
Glycogen: a Dynamic Cellular Sink and Reservoir for Carbon
All microorganisms accumulate carbon and energy reserves to cope with starvation conditions temporally present in the environment. In cyanobacteria, glycogen biosynthesis is the main strategy for metabolic sink and storage of photosynthetically fixed carbon. Glycogen biosynthesis is therefore tightly coupled to light and dark reactions of photosynthesis. Inversely, the process of glycogen degradation provides carbon and energy for adverse cellular processes.
This review summarizes the current knowledge of the chemical properties and structure of glycogen and starch-like reserves in cyanobacteria, the different enzymology and regulation of glycogen biosynthesis and degradation, and the function of glycogen metabolism in cyanobacteria. A special focus is drawn on its roles in photosynthetic efficiency, during the process of nitrogen chlorosis and for the steady-state of anabolic and catabolic reactions, especially under unbalanced growth conditions.
Cyanophycin: a Cellular Nitrogen Reserve Material
Antonia Herrero and Mireia Burnat
Cyanophycin is a biopolymer that serves as a nitrogen cellular reserve and occurs in most, albeit not all cyanobacteria. In this chapter, available information on the enzymes of cyanophycin metabolism and on the expression of the corresponding genes is reviewed. Regulation of cyanophycin production in response to the C to N balance of the cells and, in the case of heterocyst-forming cyanobacteria, the cellular specificity of cyanophycin metabolism are also addressed. Genes encoding cyanophycin metabolism proteins have also been found in bacteria other than cyanobacteria, and the polymer has been considered of potential biotechnological use. Some studies aiming at the production of cyanophycin in different bacteria and eukaryotes for its large-scale accumulation are also summarized.
Gas vesicles are hollow, organelles that provide buoyancy in aquatic prokaryotes and allow them to regulate their depth in the water column. Classic studies have shown them to be rigid and permeable to gases as large as C4F8. The wall of the hollow structure is formed entirely of protein. The principal component, GvpA (~ 7.5 kDa) is a metamorphic protein, adopting two conformations in an asymmetric dimer. These assemble into an amyloid (i.e., open-ended, cross-β) ribbon that wraps around the vesicle axis in a shallow helix and presents an aliphatic face to the interior. This aliphatic face is expected to cause evaporation of liquid water from the interior of nascent vesicles and prevent water condensation inside mature vesicles. A second protein GvpC, adheres to the GvpA shell and strengthens it. A great deal remains to be learned about how other members of the gvp gene cluster cooperate with the two main structural proteins in assembling and disassembling vesicles. Of particular interest is the fact that, despite the amyloid properties of the vesicles, the cells are able to dismantle them, in order to descend in the water column and apparently recycle protein from vesicles that have collapsed.
Motility in Unicellular and Filamentous Cyanobacteria
Bianca Brahamsha and Devaki Bhaya
Both unicellular and filamentous cyanobacteria exhibit diverse types of motility, including the ability to move on surfaces and to swim in liquids. Motile behavior can be regulated such that cyanobacteria can respond to important environmental signals such as light or chemical gradients. In some cases, components of the motility machinery, such as Type IV pili that allow certain unicellular species to move on surfaces have been characterized. In others, as is the case for swimming in certain marine unicellular species, and gliding in filamentous genera, the motility apparatus has yet to be identified. We describe here recent advances that have led to the identification of multiple photoreceptors and novel proteins involved in motility. The complex signal transduction pathways governing motile behavior and attempts to model this behavior are discussed. We conclude with some of the major challenges that remain in our understanding of the complexities of motile behavior.
Cellular Differentiation in Filamentous Cyanobacteria
Iris Maldener, Michael L. Summers and Assaf Sukenik
The ability of vegetative cells that comprise the growing filament of cyanobacteria of the order Nostocales and Stigonematales to differentiate into distinct cell types is comprehensively discussed in this chapter. Three types of differentiated cells are covered: nitrogen fixing heterocysts, dormant akinetes and motile hormogonia. While the first type represents a terminal developmental process, the two later cell types maintain the ability to resume the morphology and functions of vegetative cells including the renewal of cell division. Here we review the current knowledge and understanding of these differentiation processes that occur in cyanobacteria; from environmental signals that trigger the differentiation to the complex regulatory mechanisms that lead to morphological and functional alterations.
Cell-Cell Joining Proteins in Heterocyst-forming Cyanobacteria
The filamentous, heterocyst-forming cyanobacteria have been studied for decades as prototypes of multicellular prokaryotic organisms. They grow as rows of hundreds of cells and have been described as reproducing by random trichome breakage, implying that the unit of growth is the filament. In the heterocyst-forming cyanobacteria, nitrogen fixation and photosynthesis are spatially separated in different cell types. It is well known that filament growth under diazotrophic conditions depends on the intercellular exchange of substances between the different cell types including regulatory signal molecules and metabolites, but the possible routes through which cells communicate have only recently been subjected to study. At least two different paths could be used for cell-cell communication: the continuous periplasm that is shared by all the cells in the filament and some proteinaceous structures present at the septa between adjacent cells that can mediate, operating as channels, direct intercellular transfer of small water-soluble molecules. This chapter focuses on possible intercellular communication through septal channels and describes the proteins that could compose such channels.
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(EAN: 9781908230386 Subjects: [microbiology] [bacteriology] [environmental microbiology] )