排序方式: 共有51条查询结果,搜索用时 136 毫秒
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Casartelli Alberto Melino Vanessa J. Baumann Ute Riboni Matteo Suchecki Radoslaw Jayasinghe Nirupama S. Mendis Himasha Watanabe Mutsumi Erban Alexander Zuther Ellen Hoefgen Rainer Roessner Ute Okamoto Mamoru Heuer Sigrid 《Plant molecular biology》2019,99(4-5):477-497
Plant Molecular Biology - Degradation of nitrogen-rich purines is tightly and oppositely regulated under drought and low nitrogen supply in bread wheat. Allantoin is a key target metabolite for... 相似文献
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Plants represent the major source of food for humans, either directly or indirectly through their use as livestock feeds. Plant foods are not nutritionally balanced because they contain low proportions of a number of essential metabolites, such as vitamins and amino acids, which humans and a significant proportion of their livestock cannot produce on their own. Among the essential amino acids needed in human diets, Lys, Met, Thr and Trp are considered as the most important because they are present in only low levels in plant foods. In the present review, we discuss approaches to improve the levels of the essential amino acids Lys and Met, as well as of sulfur metabolites, in plants using metabolic engineering approaches. We also focus on specific examples for which a deeper understanding of the regulation of metabolic networks in plants is needed for tailor-made improvements of amino acid metabolism with minimal interference in plant growth and productivity. 相似文献
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Nikiforova VJ Bielecka M Gakière B Krueger S Rinder J Kempa S Morcuende R Scheible WR Hesse H Hoefgen R 《Amino acids》2006,30(2):173-183
Summary. Amino acid levels in plants are regulated by a complex interplay of regulatory circuits at the level of enzyme activities
and gene expression. Despite the diversity of precursors involved in amino acid biosynthesis as providing the carbon backbones,
the amino groups and, for the amino acids methionine and cysteine, the sulfhydryl group and despite the involvement of amino
acids as substrates in various downstream metabolic processes, the plant usually manages to provide relatively constant levels
of all amino acids. Here we collate data on how amino acid homeostasis is shifted upon depletion of one of the major biosynthetic
constituents, i.e., sulfur. Arabidopsis thaliana seedlings exposed to sulfate starvation respond with a set of adaptation processes to achieve a new balance of amino acid
metabolism. First, metabolites containing reduced sulfur (cysteine, glutathione, S-adenosylmethionine) are reduced leading
to a number of downstream effects. Second, the relative excess accumulation of N over S triggers processes to dump nitrogen
in asparagine, glutamine and further N-rich compounds like ureides. Third, the depletion of glutathione affects the redox
and stress response system of the glutathione-ascorbate cycle. Thus, biosynthesis of aromatic compounds is triggered to compensate
for this loss, leading to an increased flux and accumulation of aromatic amino acids, especially tryptophan. Despite sulfate
starvation, the homeostasis is kept, though shifted to a new state. This adaptation process keeps the plant viable even under
an adverse nutritional status. 相似文献
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MS Malamas H Stange R Schindler HJ Lankau C Grunwald B Langen U Egerland T Hage Y Ni J Erdei KY Fan K Parris KL Marquis S Grauer J Brennan R Navarra R Graf BL Harrison A Robichaud T Kronbach MN Pangalos NJ Brandon N Hoefgen 《Bioorganic & medicinal chemistry letters》2012,22(18):5876-5884
The identification of highly potent and orally active triazines for the inhibition of PDE10A is reported. The new analogs exhibit low-nanomolar potency for PDE10A, demonstrate high selectivity against all other members of the PDE family, and show desired drug-like properties. Employing structure-based drug design approaches, we investigated the selectivity of PDE10A inhibitors against other known PDE isoforms, by methodically exploring the various sub-regions of the PDE10A ligand binding pocket. A systematic assessment of the ADME and pharmacokinetic properties of the newly synthesized compounds has led to the design of drug-like candidates with good brain permeability and desirable drug kinetics (t(1/2), bioavailability, clearance). Compound 66 was highly potent for PDE10A (IC(50)=1.4nM), demonstrated high selectivity (>200×) for the other PDEs, and was efficacious in animal models of psychoses; reversal of MK-801 induced hyperactivity (MED=0.1mg/kg) and conditioned avoidance responding (CAR; ID(50)=0.2mg/kg). 相似文献
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Engineering of cysteine and methionine biosynthesis in potato 总被引:10,自引:0,他引:10
Nikiforova V Kempa S Zeh M Maimann S Kreft O Casazza AP Riedel K Tauberger E Hoefgen R Hesse H 《Amino acids》2002,22(3):259-278
Summary. Methionine and cysteine, two amino acids containing reduced sulfur, are not only an important substrate of protein biosynthesis
but are also precursors of various other metabolites such as glutathione, phytochelatines, S-adenosylmethionine, ethylene,
polyamines, biotin, and are involved as methyl group donor in numerous cellular processes. While methionine is an essential
amino acid due to an inability of monogastric animals and human beings to synthesise this metabolite, animals are still able
to convert methionine consumed with their diet into cysteine. Thus, a balanced diet containing both amino acids is necessary
to provide a nutritionally favourable food or feed source. Because the concentrations of methionine and cysteine are often
low in edible plant sources, e.g. potato, considerable efforts in plant breeding and research have been and are still performed
to understand the physiological, biochemical, and molecular mechanisms that contribute to their synthesis, transport, and
accumulation in plants. During the last decade molecular tools have enabled the isolation of most of the genes involved in
cysteine and methionine biosynthesis, and the efficient plant transformation technology has allowed the creation of transgenic
plants that are altered in the activity of individual genes. The physiological analysis of these transgenic plants has contributed
considerably to our current understanding of how amino acids are synthesised. We focused our analysis on potato (Solanum tuberosum cv. Désirée) as this plant provides a clear separation of source and sink tissues and, for applied purposes, already constitutes
a crop plant. From the data presented here and in previous work we conclude that threonine synthase and not cystathionine
gamma-synthase as expected from studies of Arabidopsis constitutes the main regulatory control point of methionine synthesis in potato. This article aims to cover the current knowledge
in the area of molecular genetics of sulfur-containing amino acid biosynthesis and will provide new data for methionine biosynthesis
in solanaceous plants such as potato.
Received December 19, 2001 Accepted January 7, 2002 相似文献