title: Leucine biosynthesis in the blue-green bacterium Anacystis nidulans.
abstract: Leucine-requiring auxotrophs of the unicellular blue-green bacterium Anacystis nidulans have been isolated. Extracts of these mutants were deficient in alpha-isopropylmalate synthetase (EC 4.1.3.12). In wild-type cells, this enzyme was subject to feedback inhibition by leucine. However, formation of the enzymes of leucine biosynthesis was little affected by exogenous leucine in either wild-type or mutant strains. Cultures of the latter subjected to extreme leucine deprivation showed no change in specific activity of beta-isopropylmalate isomerase (EC 4.2.1.33) and at most a 50% increase in the specific activity of beta-isopropylmalate dehydrogenase (EC 1.1.1.85). These results are compared with others bearing on the evolution of the control of amino acid biosynthesis in blue-green bacteria.
mesh_terms: D015079:2-Isopropylmalate Synthase / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D002474:Cell-Free System; D000458:Cyanobacteria / Q000201:enzymology / Q000378:metabolism*; D003998:Dicarboxylic Acids; D006836:Hydro-Lyases / Q000378:metabolism; D007930:Leucine / Q000096:biosynthesis* / Q000378:metabolism; D009154:Mutation; D014631:Valerates
chemical_list: D003998:Dicarboxylic Acids; D014631:Valerates; D000429:Alcohol Oxidoreductases; D015079:2-Isopropylmalate Synthase; D006836:Hydro-Lyases; D007930:Leucine