Assembly Of The Photosystem Ii Membrane Protein Complex Of Oxygenic Photosynthesis

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.

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.

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.

New possibilities have been brought about by the stunning number of genomic sequences becoming available for photosynthetic organisms. This new world of whole genome sequence data spans the phyla from photosynthetic microbes to algae to higher plants. These whole genome projects are intrinsically interesting, but also inform the variety of other molecular sequence databases including the recent 'meta-genomic' sequencing efforts that analyze entire communities of organisms. As impressive as they are, are obviously only the beginning of the effort to decipher the biological meaning encoded within them. This book aims to highlight progress in this direction. This book aims toward a genome-level understanding of the structure, function, and evolution of photosynthetic systems and the advantages accrued from the availability of phyletically diverse sets of gene sequences for the major components of the photosynthetic apparatus. While not meant to be fully comprehensive in terms of the topics covered, it does provide detailed views of specific cases and thereby illustrates important new directions that are being taken in this fast-moving field—a field that involves the integration of bioinformatics, molecular biology, physiology, and ecology.

In the modern world, to meet increasing energy demands we need to develop new technologies allowing us to use eco-friendly carbon-neutral energy sources. Solar energy as the most promising renewable source could be the way to solve that problem, but it is variable depending on day time and season. From this side, the understanding of photosynthesis process could be of significant help for us to develop effective strategies of solar energy capturing, conversion, and storage. Plants, algae, and cyanobacteria perform photosynthesis, annually producing around 100 billion tons of dry biomass. Presently, the detailed studies of photosynthetic system structure make functional investigations of the photosynthetic process available, allowing scientists to construct artificial systems for solar energy transduction. This book summarizes exciting achievements in understanding of photosynthetic structures and mechanisms of this process made by world leaders in photosynthesis field, and contains information about modern ideas in development of revolutionary new technologies of energy conversion. Organized according to the natural sequence of events occurring during photosynthesis, the book includes information of both photosynthetic structures and mechanisms and its applications in bioenergetics issues.

The leaf is an organ optimized for capturing sunlight and safely using that energy through the process of photosynthesis to drive the productivity of the plant and, through the position of plants as primary producers, that of Earth’s biosphere. It is an exquisite organ composed of multiple tissues, each with unique functions, working synergistically to: (1) deliver water, nutrients, signals, and sometimes energy-rich carbon compounds throughout the leaf (xylem); (2) deliver energy-rich carbon molecules and signals within the leaf during its development and then from the leaf to the plant once the leaf has matured (phloem); (3) regulate exchange of gasses between the leaf and the atmosphere (epidermis and stomata); (4) modulate the radiation that penetrates into the leaf tissues (trichomes, the cuticle, and its underlying epidermis); (5) harvest the energy of visible sunlight to transform water and carbon dioxide into energy-rich sugars or sugar alcohols for export to the rest of the plant (palisade and spongy mesophyll); and (6) store sugars and/or starch during the day to feed the plant during the night and/or acids during the night to support light-driven photosynthesis during the day (palisade and spongy mesophyll). Various regulatory controls that have been shaped through the evolutionary history of each plant species result in an incredible diversity of leaf form across the plant kingdom. Genetic programming is also flexible in allowing acclimatory phenotypic adjustments that optimize leaf functioning in response to a particular set of environmental conditions and biotic influences experienced by the plant. Moreover, leaves and the primary processes carried out by the leaf respond to changes in their environment, and the status of the plant, through multiple regulatory networks over time scales ranging from seconds to seasons. This book brings together the findings from laboratories at the forefront of research into various aspects of leaf function, with particular emphasis on the relationship to photosynthesis.

Algae, including cyanobacteria, are in the spotlight today for a number of reasons; firstly it has become abundantly clear over recent years that algae have been neglected in terms of basic research and that knowledge gap is being rapidly closed with the establishment of some surprising discoveries, such as the presence of Near-Infra-Red-Absorbing cyanobacteria and a wealth of natural products; secondly molecular approaches have provided a wealth of approaches to genetically modify algae and produce value-added products; thirdly it has become clear just how important, marine phytoplankton is to global carbon capture and the production of food globally; and fourthly, it has also become clear that algae present unparalleled opportunities to generate biofuels in a sustainable and non-polluting way. This volume presents 15 chapters by world experts on their subjects, ranging from reviews of algal diversity and genetics to in-depth reviews of special algal groups such as diatoms (which account for over 30% of marine carbon capture). Other chapters chart the ways in which this carbon capture occurs or how there are a multiplicity of ways in which algae intercept sun light and deploy this energy for carbon capture. A fascinating aspect here is the way in which sun light is harvested. A special chapter is devoted to the very recent and exciting possibility that algae use coherent light energy transformation to enhance the efficiency of light capture, an aspect of quantum physics that has implications for future developments at several levels and a variety of industries. Just how and why algae use Chlorophyll a as the major light capture pigment is discussed in several chapters. However, attention is also given to those cyanobacteria, which have been found to use the special Near-Infra Red absorbing chlorophylls mentioned above. And attention is also given to those algae that employ phycobiliproteins to fill in the “green window”, i.e., the spectral region from 400 – 650 nm, which is not efficiently covered by chlorophyll and carotenoid pigments. Photoinhibition and photoprotection is the subject area of several chapters and one which it is essential to understand a we work towards greater efficiency of algal photosynthesis. A final chapter is devoted to understanding the molecular basis for coral bleaching, a much-neglected area that is essential in trying to come up with solutions to this very worrying phenomenon, caused by global warming and ocean acidification. This is a book for research scientists, environmentalists, planners in a range of areas including those of marine resources, nutrient control and pollution of water bodies and that growing body of concerned citizens interested in controlling carbon emissions and global warming. Special attention has been given to generating a set of articles that will be read by university students, informed laymen and all those whose wish to understand the rapid changes that have come about in our knowledge of algae over the past decade.