A novel member of the cspA family of genes that is induced by cold shock in Escherichia coli

Escherichia coli contains a major cold shock protein, CspA (or CS7.4), whose production is predominantly induced at low temperatures. This bacterium is known to possess five additional genes, each encoding a protein highly similar to CspA (referred to as the CspA family). Here we identified a gene that encodes a cold-shock-inducible analog of CspA and CspB. This newly cloned cspG gene is located at 22 min on the E. coli genetic map, apart from the other cspA family genes. Its gene product (70 amino acids) is 73 and 77% identical to CspA (70 amino acids) and CspB (71 amino acids), respectively. Analyses of a cspG-lacZ transcriptional fusion and Northern (RNA) hybridization revealed that cspG is a low-temperature-responsive gene. Its low-temperature-inducible promoters were determined, and the results indicated that the cspG sequence is highly similar to both the cspA and cspB sequences not only in the coding regions but also in the 5'-upstream noncoding regions surrounding their own promoters.