Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The inhibition of Salmonella typhimurium by 1,2,4-triazole appears to be mediated through an effect on L-cysteine biosynthesis. O-Acetylserine sulfhydrylase A, the final enzyme in the L-cysteine biosynthetic pathway, was found to catalyze a reaction (triazolylase) between O-acetyl-L-serine and 1,2,4-triazole, giving 1,2,4-triazole-1-alanine as a product. In wild type S. typhimurium grown on 4 mM 1,2,4-triazole, 97% of the total O-acetyl-L-serine synthesized in vivo is incorporated into 1,2,4-triazole-1-alanine. 1,2,4-triazole also significantly lowers the levels of several of the enzymes necessary for sulfate reduction. This effect is presumably due to the ability of the inhibitor to lower intracellular concentrations of O-acetyl-L-serine, an inducer of these enzymes. Inhibition of growth is probably caused by L-cysteine starvation, arising from the decreased availability of the L-cysteine precursors, sulfide and O-acetyl-L-serine. Two 1,2,4-triazole-resistant strains bearing mutations in cysK, the structural gene for O-acetylserine sulfhydrylase A, incorporate only small quantities of O-acetyl-L-serine into 1,2,4-triazole-1-alanine in vivo. In vitro studies, using purified preparations of O-acetylserine sulfhydrylase A, revealed greater losses of triazolylase activity than sulfhydrylase activity in the enzymes from both cysK mutants. Resistance to 1,2,4-triazole apparently can arise from mutations leading to a preferential loss of triazolylase activity or from mutations which diminish both activities to the extent that high concentrations of O-acetyl-L-serine and sulfide accumulate behind the sulfhydrylase reaction.
 ...
PMID:Studies on the mechanism of inhibition of Salmonella typhimurium by 1,2,4-triazole. 110 Jun 24

O-Acetylserine(thiol)lyase (OASTL) enzyme catalyzes the cysteine biosynthesis in photosynthetic organisms. In mature Arabidopsis thaliana the highest activity level is observed in non-photosynthetic tissues like roots, that also show significant amount of protein detected by Western blot analysis. By means of specific probes for cytosolic and plastidic OASTL isoenzyme transcripts, cytosolic isoenzyme has been determined to be predominantly expressed in roots, while the expression of the plastidic isoform is high in both green and non-green tissues. Sulfur starvation produces an increase on the OASTL activity level in all the Arabidopsis organs examined, this effect being particularly significant in the aerial parts of the plant.
 ...
PMID:The role of roots in cysteine biosynthesis by Arabidopsis thaliana. 1022 10