Escherichia coli defects caused by null mutations in dnaK and dnaJ genes

Escherichia coli dnaJ and dnaKdnaJ mutants are defective in cell growth and survival at high temperature. Lack of DnaK and DnaJ proteins results in cell filamentation and leads to the defect in motility. Synthesis of DNA and protein is inhibited at 42 degrees C, especially in double-deletion mutant. Degradation of protein was observed in both mutants at high temperature. Complementation of these defects can be achieved by the expression of the wild-type alleles from low-copy number plasmid.