Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.2.1.22 (cystathionine beta-synthase)
 965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A cyanoalanine synthase and two isoforms (A, cytosolic and B, chloroplastic) of cysteine synthase (O:-acetylserine (thiol) lyase) were isolated from spinach. N-terminal amino acid sequence analysis of the cyanoalanine synthase gave 100% homology for the determined 12 residues with a published sequence for the mitochondrial cysteine synthase isoform. All three enzymes catalysed both the cysteine synthesis and cyanoalanine synthesis reactions, although with different efficiencies. Michaelis-Menten kinetics were observed for all three enzymes when substrate saturation experiments were performed varying O:-acetylserine, chloroalanine and cysteine. Negative co-operative kinetics were observed for cysteine synthases A and B when substrate saturation experiments were performed varying sulphide and cyanide, compared with the Michaelis-Menten kinetics observed for cyanoalanine synthase. The exception was negative co-operativity observed towards sulphide for cyanoalanine synthase with O:-acetylserine as co-substrate. The optimum sulphide concentration was dependent on the alanyl co-substrate used. The amino acid sequence similarity places these three enzymes in the same gene family, and whilst the close kinetic similarities support this, they also indicate distinct roles for the isoforms.
J Exp Bot 2000 Jun
PMID:Cysteine synthase (O-acetylserine (thiol) lyase) substrate specificities classify the mitochondrial isoform as a cyanoalanine synthase. 1094 26

Experiments were conducted to investigate the effect of S nutrition and availability on the forms of S and N in the endosperm cavity and endosperm of wheat, and on the capacity of the endosperm to utilize those compounds for the synthesis of proteins. Plants were grown in solution culture with 2 mM N and either 200 microM S (high-S) or 50 microM S (low-S) and all nutrients were withdrawn at various times from booting until 8 d post-anthesis. Sulphate was the major form of soluble S in the endosperm cavity and endosperm of high-S plants during the time of rapid grain development. By contrast, glutathione (GSH) was the major form of soluble S in the endosperm cavity and in the endosperm in low-S plants. Crude extracts of endosperm tissue from both high-S and low-S plants supported (i) the hydrolysis of GSH to gamma-glutamyl cysteine and glycine, and of gamma-glutamyl cysteine to glutamate and cysteine, and (ii) sulphate-dependent PPi-ATP exchange and the sulphydration of O-acetylserine catalysed by ATP sulphurylase and cysteine synthase, respectively. High-S nutrition enhanced the in vitro rates of ATP sulphurylase and cysteine synthase.
J Exp Bot 2001 Jul
PMID:Sulphur nutrition affects delivery and metabolism of S in developing endosperms of wheat. 1145 12

The last steps of cysteine biosynthesis are catalysed by a bi-enzyme complex composed of serine acetyltransferase (SAT) and cysteine synthase, also called O-acetyl-serine (thiol) lyase (OASTL). SAT is responsible for the production of O-acetyl-serine (OAS) from serine and acetyl-coenzyme A, while OASTL catalyses the formation of cysteine from OAS and hydrogen sulphide. Several distinct nuclear genes for SAT and OASTL enzymes exist in plants. Products of these genes are targeted into at least three cellular compartments: cytosol, chloroplasts, and mitochondria. The SAT and OASTL enzymes are strongly evolutionary conserved, both structurally and functionally. Therefore, isoenzymes from various cellular compartments can be substituted, not only by their plant counterparts from the other cellular compartments but also by their bacterial homologues. During the last decade transgenic plants overproducing SAT, OASTL or both enzymes simultaneously were obtained independently by several research groups. These manipulations led not only to the elevated levels of the respective products, namely OAS and cysteine, but also to increased amounts of glutathione and changes in the levels of other metabolites and enzymatic activities. In several cases, the transgenic plants were also shown to be less susceptible to applied abiotic stresses. In this review, all published and some unpublished results from this laboratory related to heterologous overproduction of SAT and OASTL in transgenic plants are discussed and summarized.
J Exp Bot 2004 Aug
PMID:Overproduction of SAT and/or OASTL in transgenic plants: a survey of effects. 1520 50

Integrative systems biology proposes new approaches to decipher the variation of phenotypic traits. In an effort to link the genetic variation and the physiological and molecular bases of fruit composition, the proteome (424 protein spots), metabolome (26 compounds), enzymatic profile (26 enzymes), and phenotypes of eight tomato accessions, covering the genetic diversity of the species, and four of their F1 hybrids, were characterized at two fruit developmental stages (cell expansion and orange-red). The contents of metabolites varied among the genetic backgrounds, while enzyme profiles were less variable, particularly at the cell expansion stage. Frequent genotype by stage interactions suggested that the trends observed for one accession at a physiological level may change in another accession. In agreement with this, the inheritance modes varied between crosses and stages. Although additivity was predominant, 40% of the traits were non-additively inherited. Relationships among traits revealed associations between different levels of expression and provided information on several key proteins. Notably, the role of frucktokinase, invertase, and cysteine synthase in the variation of metabolites was highlighted. Several stress-related proteins also appeared related to fruit weight differences. These key proteins might be targets for improving metabolite contents of the fruit. This systems biology approach provides better understanding of networks controlling the genetic variation of tomato fruit composition. In addition, the wide data sets generated provide an ideal framework to develop innovative integrated hypothesis and will be highly valuable for the research community.
J Exp Bot 2013 Dec
PMID:Deciphering genetic diversity and inheritance of tomato fruit weight and composition through a systems biology approach. 2415 7