Overexpression of Cold Shock Protein A of Psychromonas arctica KOPRI 22215 Confers Cold-Resistance

A polar bacterium was isolated from Arctic sea sediments and identified as Psychromonas artica, based on 16S rDNA sequence. Psychromonas artica KOPRI 22215 has an optimal growth temperature of 10 °C and a maximum growth temperature of 25 °C, suggesting this bacterium is a psychrophile. Cold shock proteins (Csps) are induced upon temperature downshift by more than 10 °C. Functional studies have researched mostly Csps of a mesophilic bacterium Escherichia coli , but not on those of psychrophilic bacteria. In an effort to understand the molecular mechanisms of psychrophilic bacteria that allow it withstand freezing environments, we cloned a gene encoding a cold shock protein from P. artica KOPRI 22215 (CspA Pa ) using the conserved sequences in csp genes. The 204 bp-long ORF encoded a protein of 68 amino acids, sharing 56% homology to previously reported E. coli CspA protein. When CspA Pa was overexpressed in E. coli , it caused cell growth-retardation and morphological elongation. Interestingly, overexpression of CspA Pa drastically increased the host’s cold-resistance by more than ten times, suggesting the protein aids survival in polar environments.