title: Evidence of an association between poly(3-hydroxybutyrate) accumulation and phosphotransbutyrylase expression in Bacillus megaterium.
abstract: Molecular analysis of a genomic region of Bacillus megaterium, a polyhydroxybutyrate (PHB)-producing microorganism, revealed the presence of a gene coding for the enzyme phosphotransbutyrylase (Ptb). Enzyme activity was measured throughout the different growth phases of B. megaterium and was found to correlate with PHB accumulation during the late-exponential growth phase. Ptb expression was repressed by glucose and activated by the branched amino acids isoleucine and valine. Overexpression of Act(Bm), a sigma(54) regulator from B. megaterium whose gene is located upstream from ptb, caused an increase in Ptb activity and PHB accumulation in B. megaterium.
authors.affiliation: Departamento de Química Biológica, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.
authors.forename: Gustavo J
authors.initials: GJ
authors.lastname: Vazquez
authors.forename: M Julia
authors.initials: MJ
authors.lastname: Pettinari
authors.forename: Beatriz S
authors.initials: BS
authors.lastname: Méndez
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000494:pharmacology; D001410:Bacillus megaterium / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002241:Carbohydrates / Q000494:pharmacology; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D006885:Hydroxybutyrates / Q000378:metabolism*; D007700:Kinetics; D010709:Phosphate Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D011091:Polyesters / Q000378:metabolism*; D051877:RNA Polymerase Sigma 54; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D000094122:Polyhydroxybutyrates
chemical_list: D000597:Amino Acids, Branched-Chain; D001426:Bacterial Proteins; D002241:Carbohydrates; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases; D006885:Hydroxybutyrates; D010709:Phosphate Acetyltransferase; D011091:Polyesters; D051877:RNA Polymerase Sigma 54; D012808:Sigma Factor; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates