title: Gratuitous repression of avtA in Escherichia coli and Salmonella typhimurium.
abstract: avtA , which encodes transaminase C (alanine-valine transaminase), is repressed by excess-L-alanine or L-leucine, and also by limitation for any of a number of amino acids in Escherichia coli and Salmonella typhimurium. Amino acid limitation causes repression by promoting the accumulation of L-alanine or L-leucine or both. avtA is also repressed by L-alpha-aminobutyric acid and other nonprotein amino acids which are structurally similar to L-alanine. We hypothesize that L-alanine and L-alpha-aminobutyric acid, whose syntheses are catalyzed by transaminase C, are the true corepressors of avtA . Repression by structural analogs of the true corepressors is termed gratuitous repression.
mesh_terms: D000409:Alanine / Q000494:pharmacology; D000596:Amino Acids / Q000494:pharmacology*; D000613:Aminobutyrates / Q000494:pharmacology; D004794:Enzyme Repression / Q000187:drug effects; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005798:Genes, Bacterial; D007930:Leucine / Q000494:pharmacology; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics; D013329:Structure-Activity Relationship; D000637:Transaminases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D000596:Amino Acids; D000613:Aminobutyrates; C012223:alpha-aminobutyric acid; D000637:Transaminases; C034522:valine-pyruvate transaminase; D007930:Leucine; D000409:Alanine