title: Mutation affecting regulation of synthesis of acetohydroxy acid synthetase in Escherichia coli K-12.
abstract: Altered regulation of synthesis of acetohydroxy acid synthetase (AHAS) was previously reported in a mutant of Escherichia coli strain K-12. The mutant strain, growing in minimal medium, exhibits a partial growth limiatation and derepression of AHAS, owing to deficient synthesis of isoleucine. The genetic lesion (ilvE503) causing the isoleucine limitation was shown to cause derepression of a valine-sensitive AHAS activity. The derepression effect of the ilvE503 mutation upon synthesis of AHAS was conclusively demonstrated by introducing both the ilvE503 allele and an altered AHAS (ilv-521) into the same cell. Evidence is presented that suggests the presence of multiple genetic regions for synthesis and control of the valine-sensitive AHAS activity.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002474:Cell-Free System; D004352:Drug Resistance, Microbial; D004794:Enzyme Repression; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D005796:Genes; D006836:Hydro-Lyases / Q000378:metabolism; D007532:Isoleucine / Q000096:biosynthesis; D009154:Mutation; D007652:Oxo-Acid-Lyases / Q000096:biosynthesis*; D011773:Pyruvates; D013912:Threonine; D000637:Transaminases / Q000378:metabolism; D014161:Transduction, Genetic; D014633:Valine / Q000096:biosynthesis / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D011773:Pyruvates; D007532:Isoleucine; D013912:Threonine; D000637:Transaminases; D007652:Oxo-Acid-Lyases; D006836:Hydro-Lyases; D014633:Valine