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Journal of Bacteriology, October 2003, p. 6005-6015, Vol. 185, No. 20
0021-9193/03/$08.00+0 DOI: 10.1128/JB.185.20.6005-6015.2003
Patricia C. Brooks, Jean-François Prost,
and Elaine O. Davis*
Division of Mycobacterial Research, National Institute for Medical Research, London NW7 1AA, England
Received 10 March 2003/ Accepted 1 August 2003
The recA gene of Mycobacterium tuberculosis is unusual in that it is expressed from two promoters, one of which, P1, is DNA damage inducible independently of LexA and RecA, while the other, P2, is regulated by LexA in the classical way (E. O. Davis, B. Springer, K. K. Gopaul, K. G. Papavinasasundaram, P. Sander, and E. C. Böttger, Mol. Microbiol. 46:791-800, 2002). In this study we characterized these two promoters in more detail. Firstly, we localized the promoter elements for each of the promoters, and in so doing we identified a mutation in each promoter which eliminates promoter activity. Interestingly, a motif with similarity to Escherichia coli
70 -35 elements but located much closer to the -10 element is important for optimal expression of P1, whereas the sequence at the -35 location is not. Secondly, we found that the sequences flanking the promoters can have a profound effect on the expression level directed by each of the promoters. Finally, we examined the contribution of each of the promoters to recA expression and compared their kinetics of induction following DNA damage.
Present address: PHLS Mycobacterium Reference Unit, South London Public Health Laboratory, King's College Hospital (Dulwich), East Dulwich Grove, London SE22 8QF, England.
Present address: Institut de Biologie et Chimie des Protéines CNRS, 69367 Lyon Cedex 07, France.
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