Expression and deletion analyses of cspE encoding cold-shock protein E in Acinetobacter oleivorans DR1

Six genes encoding cold-shock-like proteins, including cspE, are contained within the genome of Acinetobacter oleivorans DR1. All six genes are similar in size as well as amino acid identity, but appear to be differentially regulated under stressful conditions. Four of these genes (cspA, cspB, cspC and cspE) were functionally important during cold shock because of their gradual upregulation during a temperature decrease under our assay conditions. cspE also showed higher expression during alkane degradation and antibiotic exposure. The transcriptional start site of the cspE gene was determined using 5' rapid amplification of complementary DNA ends. Next, promoter analysis using numerous constructed gfp reporter strains containing deleted fragments of cspE upstream regions identified possible 5' untranslated region (UTR) cis-DNA elements that could be involved in modulating cspE expression. Deletion of cspE led to a growth defect and enhanced biofilm formation, but only at a low temperature. Collectively, our findings show the importance of CspE during cold shock, dynamic regulation of cspE expression under various stressful conditions and a possible 5'-UTR cis-DNA element for regulation of cspE expression. These data provide molecular insight into cspE gene expression during cold-shock adaptation in soil bacteria.