Previous Article | Next Article ![]()
Applied and Environmental Microbiology, October 2007, p. 6019-6029, Vol. 73, No. 19
0099-2240/07/$08.00+0 doi:10.1128/AEM.00714-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
B-Dependent and
B-Independent Mechanisms Contribute to Transcription of Listeria monocytogenes Cold Stress Genes during Cold Shock and Cold Growth
,
Department of Food Science, Cornell University, Ithaca, New York 14853
Received 29 March 2007/ Accepted 28 July 2007
The role of the stress response regulator
B (encoded by sigB) in directing the expression of selected putative and confirmed cold response genes was evaluated using Listeria monocytogenes 10403S and an isogenic
sigB mutant, which were either cold shocked at 4°C in brain heart infusion (BHI) broth for up to 30 min or grown at 4°C in BHI for 12 days. Transcript levels of the housekeeping genes rpoB and gap, the
B-dependent genes opuCA and bsh, and the cold stress genes ltrC, oppA, and fri were measured using quantitative reverse transcriptase PCR. Transcriptional start sites for ltrC, oppA, and fri were determined using rapid amplification of cDNA ends PCR. Centrifugation was found to rapidly induce
B-dependent transcription, which necessitated the use of centrifugation-independent protocols to evaluate the contributions of
B to transcription during cold shock. Our data confirmed that transcription of the cold stress genes ltrC and fri is at least partially
B dependent and experimentally identified a
B-dependent ltrC promoter. In addition, our data indicate that (i) while
B activity is induced during 30 min of cold shock, this cold shock does not induce the transcription of
B-dependent or -independent cold shock genes; (ii)
B is not required for L. monocytogenes growth at 4°C in BHI; and (iii) transcription of the putative cold stress genes opuCA, fri, and oppA is
B independent during growth at 4°C, while both bsh and ltrC show growth phase and
B-dependent transcription during growth at 4°C. We conclude that
B-dependent and
B-independent mechanisms contribute to the ability of L. monocytogenes to survive and grow at low temperatures.
Published ahead of print on 3 August 2007.
Supplemental material for this article may be found at http://aem.asm.org/.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»