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Amino Acids of the Glutamate Family: Functions beyond Primary Metabolism

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199365 Year: Pages: 206 DOI: 10.3389/978-2-88919-936-5 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Botany
Added to DOAB on : 2016-01-19 14:05:46
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The life of proteins starts and ends as amino acids. In addition to the primary function as protein building blocks, amino acids serve multiple other purposes to make a plant's life worth living. This is true especially for the amino acids of the glutamate family, namely glutamate (Glu), glutamine (Gln), proline (Pro) and arginine (Arg), as well as the product of Glu decarboxylation, ?-aminobutyric acid (GABA). Synthesis, accumulation, interconversion and degradation of these five compounds contribute in many ways to the regulation of plant development and to responses to environmental challenges. Glu and Gln hold key positions as entry points and master regulators of nitrogen metabolism in plants, and have a pivotal role in the regulatory interplay between carbon and nitrogen metabolism. Pro and GABA are among the best-studied compatible osmolytes that accumulate in response to water deficit, yet the full range of protective functions is still to be revealed. Arg, with its exceptionally high nitrogen-to-carbon ratio, has long been recognized as a major storage form of organic nitrogen. Most of the enzymes involved in metabolism of the amino acids of the glutamate family in plants have been identified or can be predicted according to similarity with animal or microbial homologues. However, for some of these enzymes the detailed biochemical properties still remain to be determined in order to understand activities in vivo. Additionally, uncertainties regarding the subcellular localization of proteins and especially the lack of knowledge about intracellular transport proteins leave significant gaps in our understanding of the metabolic network connecting Glu, Gln, Pro, GABA and Arg. While anabolic reactions are distributed between the cytosol and chloroplasts, catabolism of the amino acids of the glutamate family takes place in mitochondria and has been implicated in fueling energy-demanding physiological processes such as root elongation, recovery from stress, bolting and pollen tube elongation. Exceeding the metabolic functions, the amino acids of the glutamate family were recently identified as important signaling molecules in plants. Extracellular Glu, GABA and a range of other metabolites trigger responses in plant cells that resemble the actions of Glu and GABA as neurotransmitters in animals. Plant homologues of the Glu-gated ion channels from mammals and protein kinase signaling cascades have been implicated in these responses. Pollen tube growth and guidance depend on GABA signaling and the root architecture is specifically regulated by Glu. GABA and Pro signaling or metabolism were shown to contribute to the orchestration of defense and programmed cell death in response to pathogen attacks. Pro signaling was additionally proposed to regulate developmental processes and especially sexual reproduction. Arg is tightly linked to nitric oxide (NO) production and signaling in plants, although Arg-dependent NO-synthases could still not be identified. Potentially Arg-derived polyamines constitute the missing link between Arg and NO signaling in response to stress. Taken together, the amino acids of the glutamate family emerge as important signaling molecules that orchestrate plant growth and development by integrating the metabolic status of the plant with environmental signals, especially in stressful conditions. This research topic collects contributions from different facets of glutamate family amino acid signaling or metabolism to bring together, and integrate in a comprehensive view the latest advances in our understanding of the multiple functions of Glu-derived amino acids in plants.

Catalyzed Synthesis of Natural Products

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ISBN: 9783039219483 / 9783039219490 Year: Pages: 82 DOI: 10.3390/books978-3-03921-949-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General) --- Organic Chemistry
Added to DOAB on : 2020-01-07 09:08:26
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Natural products have been a source of inspiration for chemists and chemical biologists for many years, and have a special relevance in the chemical space. In recent years, several novel synthetic strategies have appeared, such as diversity-oriented synthesis (DOS), biological-oriented synthesis (BiOS), and function-oriented synthesis (FOS), for accessing complex and functionally diverse molecules. In this manner, the synthesis of natural products has evolved towards simpler and ecological methods using biotransformation, combinatorial chemistry, or organocatalysts. In this issue, Prof. Chojnacka shows demonstrates the use of immobilized lipases as catalysts to aid in the synthesis of phosphatidylcholine enriched with myristic acid. Profs. Vila and Pedro used catalysts derived from (S)-mandelic acid to achieve the catalytic enantioselective addition of dimethylzinc to isatins. Prof. Diez shows the possibility of the obtention of 7,8-carvone epoxides in a diastereoselective manner using proline, quinidine, and diphenylprolinol as organocatalysts. A cheap, simple, clean, and scalable method involves the use of deep eutectic mixtures as reaction media, and Profs. Alonso and Guillena describe the use of this methodology for the enantioselective, organocatalyzed ?-amination of 1,3-dicarbonyl compounds. Biotransformations have been one of the methodologies for more efficient synthesis of natural products. Prof. Wu transforms ergostane triterpenoid antcin K using Psychrobacillus sp. Ak 187. Finally, Prof. Kovayashi reviews the total synthesis and biological evaluation of phaeosphaerides. The reader, through this issue, could gain an idea of the new directions that the synthesis of natural products using catalysts will have in the years to come.

Physiological Responses to Abiotic and Biotic Stress in Forest Trees

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ISBN: 9783039215140 / 9783039215157 Year: Pages: 294 DOI: 10.3390/books978-3-03921-515-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering --- Environmental Engineering
Added to DOAB on : 2019-12-09 11:49:15
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As sessile organisms, plants have to cope with a multitude of natural and anthropogenic forms of stress in their environment. Due to their longevity, this is of particular significance for trees. As a consequence, trees develop an orchestra of resilience and resistance mechanisms to biotic and abiotic stresses in order to support their growth and development in a constantly changing atmospheric and pedospheric environment. The objective of this Special Issue of Forests is to summarize state-of-art knowledge and report the current progress on the processes that determine the resilience and resistance of trees from different zonobiomes as well as all forms of biotic and abiotic stress from the molecular to the whole tree level.

Keywords

drought --- mid-term --- non-structural carbohydrate --- soluble sugar --- starch --- Pinus massoniana --- salinity --- Carpinus betulus --- morphological indices --- gas exchange --- osmotic adjustment substances --- antioxidant enzyme activity --- ion relationships --- Populus simonii Carr. (poplar) --- intrinsic water-use efficiency --- tree rings --- basal area increment --- long-term drought --- hydrophilic polymers --- Stockosorb --- Luquasorb --- Konjac glucomannan --- photosynthesis --- ion relation --- Fagus sylvatica L. --- Abies alba Mill. --- N nutrition --- mixed stands --- pure stands --- soil N --- water relations --- 24-epiBL application --- salt stress --- ion contents --- chloroplast ultrastructure --- photosynthesis --- Robinia pseudoacacia L. --- elevation gradient --- forest type --- growth --- leaf properties --- Pinus koraiensis Sieb. et Zucc. --- Heterobasidion parviporum --- Heterobasidion annosum --- Norway spruce --- disturbance --- water availability --- pathogen --- infection --- Carpinus turczaninowii --- salinity treatments --- ecophysiology --- photosynthetic responses --- organic osmolytes --- ion homeostasis --- antioxidant enzymes --- glutaredoxin --- subcellular localization --- expression --- tapping panel dryness --- defense response --- rubber tree --- Ca2+ signal --- drought stress --- living cell --- Moso Bamboo (Phyllostachys edulis) --- plasma membrane Ca2+ channels --- signal network --- Aleppo pine --- Greece --- photosynthesis --- water potential --- ?13C --- sap flow --- canopy conductance --- climate --- molecular cloning --- functional analysis --- TCP --- DELLA --- GA-signaling pathway --- Fraxinus mandshurica Rupr. --- wood formation --- abiotic stress --- nutrition --- gene regulation --- tree --- bamboo forest --- cold stress --- physiological response --- silicon fertilization --- plant tolerance --- reactive oxygen species --- antioxidant activity --- proline --- Populus euphratica --- salt stress --- salicylic acid --- malondialdehyde --- differentially expressed genes --- n/a

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