Expression and characterization of an Acidithiobacillus ferrooxidans ATCC23270 heat shock protein hsp90 (AtHtpG) functionally expressed in Escherichia coli

摘要

A putative gene encoding the Acidithiobacillus ferrooxidans (ATCC23270) heat shock protein Hsp90 (in this paper, we named it AtHtpG) was cloned and introduced into Escherichia coli BL21 ( DE3) using the pLMl expression vector. Then the protein was successfully over expressed in Escherichia coli BL21 ( DE3 ) , and purified by one-step immobilized metal affinity chromatography. The ATPase assay showed that purified recombinant protein was in active form, and the ATPase activity of AtHtpG was temperaturedependent with an optimal temperature of 50 °C . Then we compared survivability of E. coli ( BL21) cells over expressing recombinant AtHtpG protein with the wild type BL21 under heat shock after IPTG induction. Cells over expressing recombinant AtHtpG demonstrated a remarkable growth inhibition. Further studies were carried out to analyze the characteristics of proteins from E. coli that over expressed AtHtpG. Compared to the wild type BL21, protein from strains over expressing AtHtpG exhibited lower activity when exposed to higher temperature (50°C). Our results reveal that AtHtpG is a negative modulator of the heat shock response under stress conditions.