Editor: Roger Buxton
A single-nucleotide mutation in the −10 promoter region inactivates the narK2X promoter in Mycobacterium bovis and Mycobacterium bovis BCG and has an application in diagnosis
Version of Record online: 3 DEC 2009
© 2009 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Microbiology Letters
Volume 303, Issue 2, pages 190–196, February 2010
How to Cite
Chauhan, S., Singh, A. and Tyagi, J. S. (2010), A single-nucleotide mutation in the −10 promoter region inactivates the narK2X promoter in Mycobacterium bovis and Mycobacterium bovis BCG and has an application in diagnosis. FEMS Microbiology Letters, 303: 190–196. doi: 10.1111/j.1574-6968.2009.01876.x
- Issue online: 15 JAN 2010
- Version of Record online: 3 DEC 2009
- Received 7 October 2009; revised 20 November 2009; accepted 30 November 2009.Final version published online 23 December 2009.
- Mycobacterium tuberculosis;
- Mycobacterium bovis;
Nitrate reduction is believed to be vital for the survival of tubercle bacteria under hypoxic/anaerobic conditions that are thought to prevail within granulomas. Nitrate reductase activity is rapidly induced in Mycobacterium tuberculosis (M. tb) under hypoxic conditions and is attributed to the induced expression of the nitrate/nitrite transporter gene, narK2. By contrast, Mycobacterium bovis (M. bovis) and M. bovis BCG (BCG) do not support the hypoxic induction of either nitrate reductase activity or narK2. Here, we show that the induction defect in the narK2X operon in M. bovis and BCG is caused by a −6T/C single nucleotide polymorphism (SNP) in the −10 promoter element essential for narK2X promoter activity. Complementation of M. bovis with both narGHJI and narK2X genes from M. tb failed to restore nitrate reductase activity in M. bovis, suggesting the involvement of additional genes/regulatory mechanisms for nitrate reduction that are absent in M. bovis. The −6T/C promoter-linked SNP enabled clear differentiation of M. tb from the other members of the M. tb complex, including M. bovis, BCG, Mycobacterium africanum and Mycobacterium microti, through a PCR-RFLP assay.