Assembly of the Photosystem II Membrane-Protein Complex of Oxygenic Photosynthesis PDF Download
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Author: Julian J. Eaton-Rye
Publisher: Frontiers Media SA
ISBN: 2889452336
Category :
Languages : en
Pages : 317
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Book Description
Photosystem II is a 700-kDa membrane-protein super-complex responsible for the light-driven splitting of water in oxygenic photosynthesis. The photosystem is comprised of two 350-kDa complexes each made of 20 different polypeptides and over 80 co-factors. While there have been major advances in understanding the mature structure of this photosystem many key protein factors involved in the assembly of the complex do not appear in the holoenzyme. The mechanism for assembling this super-complex is a very active area of research with newly discovered assembly factors and subcomplexes requiring characterization. Additionally the ability to split water is inseparable from light-induced photodamage that arises from radicals and reactive O2 species generated by Photosystem II chemistry. Consequently, to sustain water splitting, a “self repair” cycle has evolved whereby damaged protein is removed and replaced so as to extend the working life of the complex. Understanding how the biogenesis and repair processes are coordinated is among several important questions that remain to be answered. Other questions include: how and when are the inorganic cofactors inserted during the assembly and repair processes and how are the subcomplexes protected from photodamage during assembly? Evidence has also been obtained for Photosystem II biogenesis centers in cyanobacteria but do these also exist in plants? Do the molecular mechanisms associated with Photosystem II assembly shed fresh light on the assembly of other major energy-transducing complexes such as Photosystem I or the cytochrome b6/f complex or indeed other respiratory complexes? The contributions to this Frontiers in Plant Science Research Topic are likely to reveal new details applicable to the assembly of a range of membrane-protein complexes, including aspects of self-assembly and solar energy conversion that may be applied to artificial photosynthetic systems. In addition, a deeper understanding of Photosystem II assembly — particularly in response to changing environmental conditions — will provide new knowledge underpinning photosynthetic yields which may contribute to improved food production and long-term food security.
Author: Julian J. Eaton-Rye
Publisher: Frontiers Media SA
ISBN: 2889452336
Category :
Languages : en
Pages : 317
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Book Description
Photosystem II is a 700-kDa membrane-protein super-complex responsible for the light-driven splitting of water in oxygenic photosynthesis. The photosystem is comprised of two 350-kDa complexes each made of 20 different polypeptides and over 80 co-factors. While there have been major advances in understanding the mature structure of this photosystem many key protein factors involved in the assembly of the complex do not appear in the holoenzyme. The mechanism for assembling this super-complex is a very active area of research with newly discovered assembly factors and subcomplexes requiring characterization. Additionally the ability to split water is inseparable from light-induced photodamage that arises from radicals and reactive O2 species generated by Photosystem II chemistry. Consequently, to sustain water splitting, a “self repair” cycle has evolved whereby damaged protein is removed and replaced so as to extend the working life of the complex. Understanding how the biogenesis and repair processes are coordinated is among several important questions that remain to be answered. Other questions include: how and when are the inorganic cofactors inserted during the assembly and repair processes and how are the subcomplexes protected from photodamage during assembly? Evidence has also been obtained for Photosystem II biogenesis centers in cyanobacteria but do these also exist in plants? Do the molecular mechanisms associated with Photosystem II assembly shed fresh light on the assembly of other major energy-transducing complexes such as Photosystem I or the cytochrome b6/f complex or indeed other respiratory complexes? The contributions to this Frontiers in Plant Science Research Topic are likely to reveal new details applicable to the assembly of a range of membrane-protein complexes, including aspects of self-assembly and solar energy conversion that may be applied to artificial photosynthetic systems. In addition, a deeper understanding of Photosystem II assembly — particularly in response to changing environmental conditions — will provide new knowledge underpinning photosynthetic yields which may contribute to improved food production and long-term food security.
Author: John H. Golbeck
Publisher: Springer Science & Business Media
ISBN: 1402042566
Category : Science
Languages : en
Pages : 744
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Book Description
This book summarizes recent advances made in the biophysics, biochemistry, and molecular biology of the enzyme known as Photosystem I, the light-induced plastocyanin: ferredoxin oxidoreductase. The volume provides a unique compilation of chapters that includes information highlighting controversial issues to indicate the frontiers of research and places special emphasis on methodology and practice for new researchers.
Author: Kimberly Marie Wegener
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 227
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Book Description
Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, are present in diverse ecological niches and play crucial roles in global carbon and nitrogen cycles. To proliferate in nature, cyanobacteria utilize a host of stress responses to maintain photosynthesis under periodic changes in environmental conditions. Recent advances in proteomic study have enabled a systems-level analysis of cellular functions in many systems. Because proteins are directly responsible for cellular functions, measurements of protein abundances provide significant clues to the modulation of cellular functions during different environmental perturbations. A detailed knowledge of the composition of, as well as the dynamic changes in, the proteome is necessary to gain fundamental insights into such stress responses. Toward this goal, we have performed a large-scale proteomic analysis of the widely studied model cyanobacterium Synechocystis sp. PCC 6803 under 33 different environmental conditions. Photosystem II (PSII) is a large membrane protein complex that performs the water oxidation reactions of the photosynthetic electron transport chain in cyanobacteria, algae, and plants. Subsequently, we also performed an accurate mass tag (AMT) high-sensitivity proteomic analysis of PSII complexes purified from the cyanobacterium Synechocystis sp. PCC 6803. Taken together, these proteomics studies revealed novel information into the function and assembly of Photosystem II. We identified six PSII associated proteins that are encoded by a single operon containing nine genes, slr0144 to slr0152. This operon encodes proteins that are not essential components of the PSII holocomplex but accumulate to high levels in precomplexes lacking any of the lumenal proteins PsbP, PsbQ, or PsbV. Genetic deletion of this operon shows that removal of these protein products does not alter photoautotrophic growth or PSII fluorescence properties. Nonetheless these proteins confer fitness under competition in high light intensities. However, the deletion mutation does result in decreased PSII-mediated oxygen evolution and an altered distribution of the S states of the catalytic Mn cluster. PSII complexes isolated from [delta]slr0144 - slr0152 also show decreased photosynthetic capacity and altered polypeptide composition. These data demonstrate that the proteins encoded by the genes in this operon are necessary for optimal function of PSII and function as accessory proteins during assembly of the PSII complex. Based on these results, we have named the products of the slr0144 - slr0152 operon Pap (photosystem II assembly proteins). Additionally, through this proteomics study, we identified the protein sll1390, which we have named Psb32. To investigate its function, we analyzed subcellular localization of Psb32 and the impact of genetic deletion of the psb32 gene on PSII. Psb32 is an integral membrane protein, primarily located in the thylakoid membranes. Although not required for cell viability, Psb32 protects cells from oxidative stress and additionally confers a selective fitness advantage in mixed culture experiments. Specifically, Psb32 protects PSII from photodamage and accelerates its repair. Thus, we propose that Psb32 plays an important role in minimizing the effect of photoinhibition on PSII. Together, the proteins of the pap operon and Psb32 represent new components in PSII assembly and function.
Author: T. Wydrzynski
Publisher: Springer Science & Business Media
ISBN: 140204254X
Category : Science
Languages : en
Pages : 786
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Book Description
The most mysterious part of photosynthesis yet the most important for all aerobic life on Earth (including ourselves) is how green plants, algae and cyanobacteria make atmospheric oxygen from water. This thermodynamically difficult process is only achieved in Nature by the unique pigment/protein complex known as Photosystem II, using sunlight to power the reaction. The present volume contains 34 comprehensive chapters authored by 75 scientific experts from around the world. It gives an up-to-date account on all what is currently known about the molecular biology, biochemistry, biophysics and physiology of Photosystem II. The book is divided into several parts detailing the protein constituents, functional sites, tertiary structure, molecular dynamics, and mechanisms of homeostasis. The book ends with a comparison of Photosystem II with other related enzymes and bio-mimetic systems. Since the unique water-splitting chemistry catalyzed by Photosystem II leads to the production of pure oxygen gas and has the potential for making hydrogen gas, a primary goal of this book is to provide a molecular guide to future protein engineers and bio-mimetic chemists in the development of biocatalysts for the generation of clean, renewable energy from sunlight and water.
Author: Hajime Wada
Publisher: Springer Science & Business Media
ISBN: 9048128633
Category : Science
Languages : en
Pages : 506
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Book Description
Lipids in Photosynthesis: Essential and Regulatory Functions, provides an essential summary of an exciting decade of research on relationships between lipids and photosynthesis. The book brings together extensively cross-referenced and peer-reviewed chapters by prominent researchers. The topics covered include the structure, molecular organization and biosynthesis of fatty acids, glycerolipids and nonglycerolipids in plants, algae, lichens, mosses, and cyanobacteria, as well as in chloroplasts and mitochondria. Several chapters deal with the manipulation of the extent of unsaturation of fatty acids and the effects of such manipulation on photosynthesis and responses to various forms of stress. The final chapters focus on lipid trafficking, signaling and advanced analytical techniques. Ten years ago, Siegenthaler and Murata edited "Lipids in Photosynthesis: Structure, Function and Genetics," which became a classic in the field. "Lipids in Photosynthesis: Essential and Regulatory Functions," belongs, with its predecessor, in every plant and microbiological researcher's bookcase.
Author: Govindjee
Publisher: Springer Science & Business Media
ISBN: 9400922698
Category : Science
Languages : en
Pages : 825
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Book Description
Molecular biology, particularly molecular genetics, is among the newest and most powerful approach in modern photosynthesis research. Development of molecular biology techniques has provided new methods to solve old problems in many biological disciplines. Molecular biology has its greatest potential for contribution when applied in combination with other disciplines, to focus not just on genes and molecules, but on the complex interaction between them and the biochemical pathways in the whole organism. Photosynthesis is surely the best studied research area in plant biology, making this field the foremost candidate for successfully employing molecular genetic techniques. Already, the success of molecular biology in photosynthesis has been nothing short of spectacular. Work performed over the last few years, much of which is sum marized in this volume, stands in evidence. Techniques such as site-specific mutagenesis have helped us in examining the roles of individual protein domains in the function of multiunit complexes such as the enzyme ribulose-l ,5-bisphos phate carboxylase/oxygenase (RUBISCO) and the oxygen evolving photo system (the photosystem II). The techniques of molecular biology have been very important in advancing the state of knowledge of the reaction center from the photosynthetic bacteria whose structure has been elegantly deduced by H. Michel and 1. Deisenhofer from the X-ray studies of its crystals.
Author: Donald R. Ort
Publisher: Springer Science & Business Media
ISBN: 0306481278
Category : Science
Languages : en
Pages : 681
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Book Description
Structure and function of the components of the photosynthetic apparatus and the molecular biology of these components have become the dominant themes in advances in our understanding of the light reactions of oxygenic photosynthesis. Oxygenic Photosynthesis: The Light Reactions presents our current understanding of these reactions in thylakoid membranes. Topics covered include the photosystems, the cytochrome b6-f complex, plastocyanin, ferredoxin, FNR, light-harvesting complexes, and the coupling factor. Chapters are also devoted to the structure of thylakoid membranes, their lipid composition, and their biogenesis. Updates on the crystal structures of cytochrome f, ATP synthase and photosystem I are presented and a section on molecular biology and evolution of the photosynthetic apparatus is also included. The chapters in this book provide a comprehensive overview of photosynthetic reactions in eukaryotic thylakoids. The book is intended for a wide audience, including graduate students and researchers active in this field, as well as those individuals who have interests in plant biochemistry and molecular biology or plant physiology.
Author: H.A. Frank
Publisher: Springer Science & Business Media
ISBN: 0306482096
Category : Science
Languages : en
Pages : 406
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Book Description
Written by leading experts in the area of carotenoid research, this book gives a comprehensive overview of a various topics in the field. The contributions review the basic hypotheses about how carotenoids function and give details regarding testing different molecular models using state-of-the-art experimental methodologies.
Author: Paul-André Siegenthaler
Publisher: Springer Science & Business Media
ISBN: 0306480875
Category : Science
Languages : en
Pages : 328
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Book Description
Lipids in Photosynthesis provides readers with a comprehensive view of the structure, function and genetics of lipids in plants, algae and bacteria, with special emphasis on the photosynthetic apparatus in thylakoid membranes. This volume includes the historical background of the field, as well as a full review of our current understanding of the structure and molecular organization of lipids and their role in the functions of photosynthetic membranes. The physical properties of membrane lipids in thylakoid membranes and their relationship to photosynthesis are also discussed. Other topics include the biosynthesis of glycerolipids and triglycerides; reconstitution of photosynthetic structures and activities with lipids; lipid-protein interactions in the import of proteins into chloroplasts; the development of thylakoid membranes as it relates to lipids; genetic engineering of the unsaturation of membrane glycerolipids, with a focus on the ability of the photosynthetic machinery to tolerate temperature stress; and the involvement of chloroplast lipids in the reactions of plants upon exposure to stress. This book is intended for a wide audience and should be of interest to advanced undergraduate and graduate students and to researchers active in the field, as well as to those scientists whose fields of specialization include the biochemistry, physiology, molecular biology, biophysics and biotechnology of membranes.
Author: Robert Harry Calderon
Publisher:
ISBN:
Category :
Languages : en
Pages : 73
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Book Description
Photosystem II (PSII) is the protein-pigment complex in oxygenic photosynthesis that uses light energy to catalyze the oxidation of water. How the subunits and cofactors that make up this enzyme are properly assembled into a functional photosystem remains unknown. I sought to find and characterize previously unknown proteins involved in this process by screening a population of insertional mutants of the unicellular green alga Chlamydomonas reinhardtii. One mutant, which I named the second photosystem assembly component (2pac), contained a deletion of a gene encoding a membrane-bound rubredoxin (RBD1) and, as a result, displayed a PSII-specific phenotype. I then characterized plant and cyanobacterial mutants lacking the RBD1 ortholog and found that they too displayed a PSII-specific phenotype. To uncover the precise role of this rubredoxin in the assembly of PSII, I further characterized the 2pac mutant and found that PSII subunits were translated in the mutant but unstable. I found that the low level of PSII subunits that did accumulate in 2pac were assembled into PSII monomers but not dimers. By analyzing 2D-PAGE gels, I observed a comigration of RBD1 and the PSII subunit CP43, supporting a possible interaction between the two proteins. We attempted to further characterize interacting partners of RBD1 by coexpression of RBD1 and genes encoding PSII subunits in yeast and found an interaction between RBD1 and the PsbI protein. Taken together, the data are consistent with a model in which RBD1 aids in the fusion of a CP43-containing precomplex with the nascent PSII reaction center during formation of the PSII monomer. Because rubredoxins are known to be redox-active proteins in non-photosynthetic organisms, we hypothesized that RBD1 might be required for a redox modification of PSII during its biogenesis. We tested this by combining the 2pac mutation with a mutation in the gene encoding the chloroplast protease FtsH1 (which is known to degrade damaged or misassembled PSII) in order to accumulate more PSII in the 2pac mutant background for study. We found that PSII did indeed accumulate to a higher level in this double mutant strain (2pac ftsh1-1) than in the 2pac mutant. We also found the PSII in this strain to be much more light-sensitive than a wild-type PSII, supporting our hypothesis. We were unable to resolve any differences in cofactor or subunit composition, but we were able to rule out several candidate subunits and a cofactor. In order to find other genes like RBD1 that are responsible for PSII function, I devised a phylogenomic approach to search the publicly available genomes of oxygenic photoautotrophs for genes that had a specific phylogenetic signature. I hypothesized that genes required for PSII function would be present in the genomes of all oxygenic photoautotrophs except for the cyanobacterium UCYN-A, which lacks genes for PSII due to its symbiotic relationship with a diatom. The preliminary results indicated that some genes found through this approach might indeed be associated with PSII.
