Screening of genes regulated by cold shock in Shewanella piezotolerans WP3 and time course expression of cold-regulated genes

The differential gene transcription of a deep-sea bacterium Shewanella piezotolerans WP3 in response to cold shock was analyzed by RNA arbitrarily primed PCR. Ninety primer sets were used to scan two different RNA pools derived from the culture of cold shock and its control (culture at its optimal grown temperature). Ninety-four putative differentially expressed fragments were identified and cloned. Six out of the 94 fragments were confirmed to be truly differentially transcribed in terms of cold shock by reverse Northern dot blot and then sequenced. Sequence blast analysis showed that the six differentially transcribed genes are putative genes for zonular occludens toxin, chaperon GroEL, efflux transporter, Sua5/YciO/YrdC/YwlC family protein, betaine-aldehyde dehydrogenase, and DEAD box RNA helicase, respectively. The time course expression profiles of these six genes from 0 to 90 min upon cold shock were quantified by real-time PCR. Deletion mutation of the highest induced gene--RNA helicase gene, had no significant impact on the growth of the strain no matter upon cold shock or under permanent low temperature. It is suggested that one or more additional DEAD box RNA helicase genes compensate for the loss of the function of the mutated gene.