Mapping of the Bacillus subtilis cspB gene and cloning of its homologs in thermophilic, mesophilic and psychrotrophic bacilli.

The Bacillus subtilis cold shock (CS)-inducible gene, cspB, encoding the nucleic-acid-binding, major CS protein CspB, is located at about 80 degrees on the B. subtilis genetic map. Using this cspB as a probe, the CspB-encoding genes from two thermophilic bacilli were cloned and characterized. The nucleotide (nt) sequences of the B. caldolyticus and B. stearothermophilus cspB coding regions are 78 and 76% identical to the B. subtilis cspB and the deduced amino acid (aa) sequences revealed 84 and 82% identity, respectively. The cspB genes of the mesophilic B. globigii and the some what psychrotrophic B. globisporus, were amplified by PCR using mixed degenerate oligodeoxyribonts based on the 5' and 3' ends of B. subtilis cspB. The nt sequence comparisons of the resulting cloned PCR fragments revealed 98 to 99% identity to cspB of B. subtilis and 97% aa identity to the CspB protein. The high conservation of CspB within the genus Bacillus and the presence of a related nucleic acid-binding domain within several eukaryotic transcription factors implies an important common biological function that seems to be highly conserved from bacteria to man.