Phosphotransacetylase as a key factor in biological production of polyhydroxybutyrate.
Phosphotransacetylase (Pta) catalyzes the reversible conversion of acetyl-coenzyme A (CoA) to acetyl phosphate. Polyhydroxybutyrate (PHB) synthase and accumulation were compared between a Pta-deficient mutant and the wild-type Escherichia coli, which were transformed with pAE100, coding for 3-ketothiolase, NADPH-dependent acetoacetyl-CoA reductase, and PHB synthase from Ralstonia eutropha. During the growth period, PHB synthase activity in the Pta-deficient mutant was lower than that in the wild type. PHB accumulation in the Pta-deficient mutant, however, was higher than that in wild-type cells grown in Luria-Bertani (LB) medium containing 1% glucose (high C:N ratio). The Pta-deficient mutant showed PHB accumulation even in LB medium (low C:N ratio), whereas wild-type cells showed no PHB accumulation. These data suggest the activation of PHB synthase by acetyl phosphate that is synthesized by Pta. A decrease in Pta activity probably causes some increase in acetyl-CoA as substrate for the PHB synthesis pathway, resulting in increased PHB accumulation.
Miyake
M
M
National Institute of Bioscience and Human-Technology, Ibaraki, Japan. mmiyake@nibh.go.jp
Miyamoto
C
C
Schnackenberg
J
J
Kurane
R
R
Asada
Y
Y
D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000429:Alcohol Oxidoreductases; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology; D006885:Hydroxybutyrates / Q000138:chemical synthesis*; D010709:Phosphate Acetyltransferase; D011091:Polyesters / Q000138:chemical synthesis*; D000091402:Prohibitins; D011994:Recombinant Proteins / Q000378:metabolism
D006885:Hydroxybutyrates; C000717328:PHB protein, human; D011091:Polyesters; D000091402:Prohibitins; D011994:Recombinant Proteins; D000429:Alcohol Oxidoreductases; C023744:acetoacetyl-CoA reductase; D000217:Acyltransferases; C077225:poly(3-hydroxyalkanoic acid) synthase; D010709:Phosphate Acetyltransferase