Slow induction of RecA by DNA damage in Mycobacterium tuberculosis

• Published in: Microbiology (Society for General Microbiology) 2001-12, Vol.147 (12), p.3271-3279
• Main Authors: Papavinasasundaram, K. G, Anderson, Colin, Brooks, Patricia C, Thomas, Nicola A, Movahedzadeh, Farahnaz, Jenner, Peter J, Colston, M. Joseph, Davis, Elaine O
• Format: Article
• Language: English
• Subjects: Alkylating Agents - pharmacology; Bacterial diseases; Bacterial Proteins - metabolism; Biological and medical sciences; DNA Damage - genetics; Enzyme Induction; Experimental bacterial diseases and models; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Human bacterial diseases; Infectious diseases; LexA protein; Medical sciences; Microbiology; Mitomycin - pharmacology; mitomycin C; Mycobacterium smegmatis; Mycobacterium smegmatis - genetics; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Promoter Regions, Genetic; Protein Binding; Rec A Recombinases - biosynthesis; Rec A Recombinases - genetics; Repressor Proteins - metabolism; Serine Endopeptidases - metabolism; Species Specificity; Tuberculosis and atypical mycobacterial infections
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-147-12-3271

Division of Mycobacterial Research, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK 1 Author for correspondence: K. G. Papavinasasundaram. Tel: [phone]. Fax: [phone]. e-mail: kpapavi{at}nimr.mrc.ac.uk In mycobacteria, as in most bacterial species, the expression of RecA is induced by DNA damage. However, the authors show here that the kinetics of recA induction in Mycobacterium smegmatis and in Mycobacterium tuberculosis are quite different: whilst maximum expression in M. smegmatis occurred 3–6 h after addition of a DNA-damaging agent, incubation for 18–36 h was required to reach peak levels in M. tuberculosis . This is despite the fact that the M. tuberculosis promoter can be activated more rapidly when transferred to M. smegmatis . In addition, it is demonstrated that in both species the DNA is sufficiently damaged to give maximum induction within the first hour of incubation with mitomycin C. The difference in the induction kinetics of recA between the two species was mirrored by a difference in the levels of DNA-binding-competent LexA following DNA damage. A decrease in the ability of LexA to bind to the SOS box was readily detected by 2 h in M. smegmatis , whilst a decrease was not apparent until 18–24 h in M. tuberculosis and then only a very small decrease was observed. Keywords: LexA, SOS induction, mycobacteria a Present address: Trescowthick Research Laboratories, Peter MacCallum Cancer Institute, Locked Bag 1, A’Beckett Street, Melbourne VIC 8006, Australia. b Present address: London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.