Analysis of the relationship between Era and YggG in E. coli by double-promoter expression vector pDH2-YggG-Ptac-Era
利用双启动子表达载体pDH2-YggG-Ptac-Era研究E. coli Era和YggG 蛋白间的相互关系

yggG, a Era-binding protein gene, was isolated and cloned from the E.coli genomic DNA library. Previous studies indicated that the product of yggG gene, YggG294(amino acids 1-294), strongly inhibited the growth of host bacteria and caused the death of bacteria cells. To elucidate whether Era is related to the death of bacterial cells expressed YggG294,A double promoter expression vector that can express YggG294 and Era proteins controllably in cells was constructed. Using this vector to express YggG294 and Era protein in the same E.coli cells, then analyzed the relation between YggG294 and Era. The results showed that the ratio of Era proteins to total proteins increased with the increase of induction time in E.coli cells without YggG294 expression and with little YggG294 expression;the ratio of Era proteins to total proteins seemed to be a constant level in E.coli cells overexpressing YggG294;but we could not detect any Era hydrolyzate in E.coli cells overexpressed YggG294 could not be detected. The results also showed that pre-expression of Era protein did not produce any effect on the growth inhibition of E.coli cells caused by YggG294. These results indicate that YggG294 can not hydrolyze Era protein in E.coli cells, and that YggG-Era interaction is not associated with the death of bacteria expressed YggG294. It is thus reasonable to draw a conclusion that Era is not associated with the growth inhibition of E.coli cells caused by YggG294. YggG294 inhibits the growth of bacteria by other way.