Temperature adaptation of Bacillus subtilis by chromosomal groEL replacement.

We investigated a temperature adaptation of Bacillus subtilis 168 in which chromosomal groEL was replaced with a psychrophilic groEL. This strain can grow at 50 degrees C but not at 51 degrees C, a temperature at which wild-type B. subtilis can grow. Using in vivo random mutagenesis by the B. subtilis mutator strain (mutS, mutM, mutY), two thermo-adaptants were isolated from the groEL substituted strain at 52 degrees C. They contained novel amino acid alterations in their ATP binding motif (T93I) and the inter-monomer contact (R285H) region of GroEL. These results suggest that GroEL participates in bacterial temperature adaptation.