A common regulator of cold and radiation response in Escherichia coli.

High levels of the protein product of gicA/cspE, a member of cspA family of cold stress genes, are known to be associated with several pleiotropic phenotypes in Escherichia coli. These include growth retardation in cold, suppression of rpsL31-mediated streptomycin resistance in cold, suppression of the chromosome partitioning mutation mukB, and cellular resistance to camphor. In this article, we demonstrate that the product of this gene is also involved in regulating UV and gamma radiation sensitivity. When present on a multicopy plasmid, gicA conferred UV sensitivity on those strains of E. coli K-12, in which it produces the cold-dependent growth retardation and streptomycin sensitivity but did not confer any gamma radiation sensitivity. A gicA::cat mutation, that inactivates the chromosomal gicA, made the cells highly sensitive to both UV and gamma radiation. These results indicate that the cellular level of GicA is quite critical in some aspects of DNA metabolism and suggest that this protein is a global regulator of multiple pathways affecting growth and translational fidelity in cold, DNA condensation, and chromosome partitioning during cell division.