Characterization of cspB, a cold-shock-inducible gene from Lactococcus lactis, and evidence for a family of genes homologous to the Escherichia coli cspA major cold shock gene.

Upon temperature downshift, the major cold shock protein CspA is highly induced in Escherichia coli. This protein being conserved in other bacteria, we used a PCR-based approach with a pair of degenerate primers derived from highly conserved regions of the CspA-related proteins to evidence the presence of at least three related genes in Lactococcus lactis. One of them, cspB, was cloned and sequenced. It encodes a 66-residue protein which possesses 60% sequence identity with E. coli CspA. Following a cold shock from 30 to 15 degrees C, the level of the cspB mRNA transcript increased, as shown by Northern blot hybridization. In addition, induction of cspB-directed beta-galactosidase activity was observed. These results indicate that the L. lactis cspB gene is cold shock inducible.