Proteome analysis of a temperature-inducible recombinant Escherichia coli for poly-beta-hydroxybutyrate production

A recombinant Escherichia coli strain harboring the lambdap(R)-p(L) promote r and heterologous poly-beta -hydroxybutyrate (PHB) biosynthesis genes was shown to accumulate PHB when the incubation temperature was changed from 34 degreesC to temperatures higher than 37 degreesC. In the present research, total gene expression patterns of the recombinant E. coli before and after induction were investigated by two-dimensional gel electrophoresis. Protei ns encoded by serS, sucC, trpA, and alaS were found to be expressed before induction of phb genes at a culture temperature of 34 degreesC. On the othe r hand, proteins encoded by metG, rpII, and carA were found to be expressed after induction achieved by increasing the temperature to 40 degreesC. In the case of plasmid-free cells, all the selected genes have been shown to b e expressed except metG, and ibpA and ihpB among the heat-shock proteins. T he heat-shock proteins were found to be upregulated upon induction of phb g enes, which may be due to the stress caused by the accumulation of PHB gran ules as well as by the temperature upshift. The changes in the expression o f some of the metabolic pathway-related proteins before and after induction were interpreted in relation to the consumption of NADPH and acetyl-CoA fo r PHB synthesis.