Screening of genes regulated by cold shock in Shewanella piezotolerans WP3 and time course expression of cold-regulated
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ORIGINAL PAPER
Screening of genes regulated by cold shock in Shewanella piezotolerans WP3 and time course expression of cold-regulated genes Shengkang Li Æ Xiang Xiao Æ Ping Sun Æ Fengping Wang
Received: 2 August 2007 / Revised: 5 December 2007 / Accepted: 11 December 2007 / Published online: 10 January 2008 Ó Springer-Verlag 2008
Abstract The differential gene transcription of a deepsea 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). Ninetyfour 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, betainealdehyde 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.
Communicated by John Helmann. S. Li X. Xiao P. Sun F. Wang (&) Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen, People’s Republic of China e-mail: [email protected] S. Li e-mail: [email protected]
Keywords Shewanella piezotolerans WP3 RAP-PCR Differential-expressed fragments Time course expression Mutation
Introduction Temperature change might be the most common stress that all living organisms encounter in natural habitats. To overcome critical situations which could be generated by extreme temperatures, bacteria have evolved complex and specific mechanisms that are called cold shock and heat shock responses (Phadtare et al. 1999; Saeed et al. 2003). The cold shock in mesophilic bacterium Escherichia coli has been intensively studied, in which the induction of the cold shock proteins (CSPs), synthesis of the proteins involved in transcription and translation, and repression of heat shock proteins were observed by cold shock (Jones and Inouye 1994; Gualerzi et al. 2003). E. coli K-12 encodes nine csp genes, but only four of them are strongly induced under cold shock (Wang et al. 1999). It is assumed that other members of the CSP family are involved in the protection against stresses other than low temperature (Graumann and Marahiel 1998). In Bacillus subtilis, a temperature downshift induced the accumulation of three CSPs: CspB, CspC and CspD (Graumann et al
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