Initial studies on aBacillus subtilis mutant lacking the dnaK-homologue protein

A sequence of 412bp, spanning the terminal half of thegrpE and the proximal portion of thednaK-homologues inBacillus subtilis, was amplified with PCR technology. This fragment was cloned into pJH101, anEscherichia coli plasmid, and transformed intoB. subtilis strain YB886. Several chloramphenicol-resistant colonies were obtained from this transformation. The integration of the plasmid into theB. subtilis chromosome was verified by restriction endonuclease analysis and Southern hybridization. Strain BUL101, a chloramphenicol-resistant transformant, lacked the DnaK-homologue as demonstrated by two-dimensional polyacrylamide gel electrophoresis and Western blot analysis. BUL101 grew at slower rates than parental cells at both 37°C and 48°C, produced abnormal cell shapes at 48°C, and was unable to grow at 51°C. The 412bp fragment did not exhibit detectable promoter activity.