Post Translational Modification And Regulation Of Oxophytodienoate Reductase 3 Opr3 Band 14

Oxophytodienoic acid reductases (OPRs) are flavoenzymes closely related to Old Yellow Enzyme (OYE) from Saccharomyces. The physiological role of plant OPRs could only be clarified for OPR3: OPR3 from tomato and Arabidopsis reduce the double bond of the α,β-unsaturated carbonyl group of (9S,13S)-oxophytodienoic acid (OPDA), the precursor of the phytohormone jasmonic acid (JA). OPR3 is therefore an important step for JA biosynthesis and the following JA-triggered defensive and developmental adaptations of the plant. Since the production of phytohormones, including JA, is regulated in an extremely time- and tissue specific manner, the regulatory step of JA-biosynthesis was sought. The conversion of OPDA by OPR3 was proposed as the rate-limiting step in biosynthesis as OPR3 turned out to form a self-inhibiting dimer when crystallized. In the OPR3 crystal, the L6-loop from each protomer reaches into the active site cavity of the other protomer. The dimerization-dependent block of the active site provides a hypothetical mechanism for the regulation of OPR3 activity. Interestingly, two sulfate ions were enclosed in the interacting site of the protomers, suggesting that the dimer might be stabilized in vivo by reversible sulfation or phosphorylation of the tyrosine 364(SlOPR3) or 365 (AtOPR3), respectively. The role of this hypothesized sulfation/phosphorylation was subject of this study. Neither sulfation nor phosphorylation of Y365 could be detected by mass spectrometry. Hence, studies were continued with an in vitro approach where OPR3 was expressed with sulfotyrosine incorporated co-translationally at position 365 (Y365SY). Biochemical characterization led to contradictory results: On the one hand, interaction strength of Y365SY was unaltered in comparison to wild-type OPR3, while on the other hand, activity of Y365SY was reduced. Closer examination indicated that substrate binding or product release was reduced in Y365SY. These changes could be traced back to the additional charge of the SO42—ion, which leads to a narrowing of the entrance to the active site cavity. With this finding, the proposed regulating mechanism by sulfation/phosphorylation is still valid, but independent from dimerization. In order to link this potential regulatory mechanism with a post-translational modification in vivo, an untargeted screen was performed, in which OPR3 was expressed as a fusion protein with a promiscous biotin ligase (BioID2). With this method, potentially interacting proteins were biotinylated in vivo and subsequently isolated and analyzed by MS/MS. Many candidate proteins were identified for OPR3, including kinases and phosphatases. Additionally, OPR1, OPR2 and OPR4 from Arabidopsis were also expressed as BioID2 fusion proteins in order to clarify their physiological role. The most promising results were obtained for OPR4, which was found to be association with stress granule and P-body proteins.

In the two decades since the last comprehensive work on plant peroxisomes appeared, the scientific approaches employed in the study of plant biology have changed beyond all recognition. The accelerating pace of plant research in the post-genomic era is leading us to appreciate that peroxisomes have many important roles in plant cells, including reserve mobilisation, nitrogen assimilation, defence against stress, and metabolism of plant hormones, which are vital for productivity and normal plant development. Many plant scientists are finding, and will no doubt continue to find, that their own area of research is connected in some way to peroxisomes. Written by the leading experts in the field, this book surveys peroxisomal metabolic pathways, protein targeting and biogenesis of the organelle and prospects for the manipulation of peroxisomal function for biotechnological purposes. It aims to draw together the current state of the art as a convenient starting point for anyone, student or researcher, who wishes to know about plant peroxisomes.

A collection of papers that comprehensively describe the major areas of research on lipid metabolism of plants. State-of-the-art knowledge about research on fatty acid and glycerolipid biosynthesis, isoprenoid metabolism, membrane structure and organization, lipid oxidation and degradation, lipids as intracellular and extracellular messengers, lipids and environment, oil seeds and gene technology is reviewed. The different topics covered show that modern tools of plant cellular and molecular biology, as well as molecular genetics, have been recently used to characterize several key enzymes of plant lipid metabolism (in particular, desaturases, thioesterases, fatty acid synthetase) and to isolate corresponding cDNAs and genomic clones, allowing the use of genetic engineering methods to modify the composition of membranes or storage lipids. These findings open fascinating perspectives, both for establishing the roles of lipids in membrane function and intracellular signalling and for adapting the composition of seed oil to the industrial needs. This book will be a good reference source for research scientists, advanced students and industrialists wishing to follow the considerable progress made in recent years on plant lipid metabolism and to envision the new opportunities offered by genetic engineering for the development of novel oil seeds.

Plant Signaling Molecule: Role and Regulation under Stressful Environments explores tolerance mechanisms mediated by signaling molecules in plants for achieving sustainability under changing environmental conditions. Including a wide range of potential molecules, from primary to secondary metabolites, the book presents the status and future prospects of the role and regulation of signaling molecules at physiological, biochemical, molecular and structural level under abiotic stress tolerance. This book is designed to enhance the mechanistic understanding of signaling molecules and will be an important resource for plant biologists in developing stress tolerant crops to achieve sustainability under changing environmental conditions. Focuses on plant biology under stress conditions Provides a compendium of knowledge related to plant adaptation, physiology, biochemistry and molecular responses Identifies treatments that enhance plant tolerance to abiotic stresses Illustrates specific physiological pathways that are considered key points for plant adaptation or tolerance to abiotic stresses

Programmed cell death is a common pattern of growth and development in both animals and plants. However, programmed cell death and related processes are not as generally recognized as central to plant growth. This is changing fast and is becoming more of a focus of intensive research. This edited work will bring under one cover recent reviews of programmed cell death, apoptosis and senescence. Summaries of the myriad aspects of cell death in plants Discussion of the broadest implications of these disparite results A unification of fields where there has been no cross talk Enables easy entry into diverse but related lines of research

Plant Hormones: Biosynthesis and Mechanisms of Action is based on research funded by the Chinese government’s National Natural Science Foundation of China (NSFC). This book brings a fresh understanding of hormone biology, particularly molecular mechanisms driving plant hormone actions. With growing understanding of hormone biology comes new outlooks on how mankind values and utilizes the built-in potential of plants for improvement of crops in an environmentally friendly and sustainable manner. This book is a comprehensive description of all major plant hormones: how they are synthesized and catabolized; how they are perceived by plant cells; how they trigger signal transduction; how they regulate gene expression; how they regulate plant growth, development and defense responses; and how we measure plant hormones. This is an exciting time for researchers interested in plant hormones. Plants rely on a diverse set of small molecule hormones to regulate every aspect of their biological processes including development, growth, and adaptation. Since the discovery of the first plant hormone auxin, hormones have always been the frontiers of plant biology. Although the physiological functions of most plant hormones have been studied for decades, the last 15 to 20 years have seen a dramatic progress in our understanding of the molecular mechanisms of hormone actions. The publication of the whole genome sequences of the model systems of Arabidopsis and rice, together with the advent of multidisciplinary approaches has opened the door to successful experimentation on plant hormone actions. Offers a comprehensive description of all major plant hormones including the recently discovered strigolactones and several peptide hormones Contains a chapter describing how plant hormones regulate stem cells Offers a fresh understanding of hormone biology, particularly molecular mechanisms driving plant hormone actions Discusses the built-in potential of plants for improvement of crops in an environmentally friendly and sustainable manner

This book summarizes recent advances in understanding the functions of plant and algal lipids in photosynthesis, in development and signaling, and in industrial applications. As readers will discover, biochemistry, enzymology and analytical chemistry, as well as gene knock-out studies have all contributed to our rapidly increasing understanding of the functions of lipids. In the past few decades, distinct physical and biochemical properties of specific lipid classes were revealed in plant and algal lipids and the functional aspects of lipids in modulating critical biological processes have been uncovered. These chapters from international authors across relevant research fields highlight the underlying evolutionary context of lipid function in photosynthetic unicellular and multicellular organisms. The book goes on to encompass what lipids can do for industrial applications at a time of fascination with plants and algae in carbon fixation and as sources for production of food, energy and novel chemicals. The developmental context is a part of the fresh and engaging perspective that is presented in this work which graduate students and scientists will find both illuminating and useful.