Impairment of nucleoid segregation and cell division at high osmolarity in a strain of Escherichia coli overproducing the chaperone DnaK.

Escherichia coli strain WM1390, which overproduces 20-fold the chaperone protein DnaK, was able to grow exponentially without apparent abnormality in 300 mosM medium. In contrast, it showed both aberrant nucleoid segregation and strong inhibition of septation when shifted to high osmolarity. These impairments could not be accounted for by a bacteriocidal effect of the high DnaK content. Rather, the DnaK content appeared to promote faster growth than that of the parent C600, at least at high osmolarity in the presence of the osmoprotectant glycine betaine.