Email updates

Keep up to date with the latest news and content from BMC Microbiology and BioMed Central.

Open Access Research article

The mycobacterial DNA-binding protein 1 (MDP1) from Mycobacterium bovis BCG influences various growth characteristics

Astrid Lewin1*, Daniela Baus2, Elisabeth Kamal1, Fabienne Bon3, Ralph Kunisch1, Sven Maurischat1, Michaela Adonopoulou4 and Katharina Eich1

Author Affiliations

1 Robert-Koch-Institut, Nordufer 20, 13353 Berlin, Germany

2 Sanofi-Aventis Germany GmbH, TD Metabolism, 65926 Frankfurt am Main, Germany

3 IUT de Dijon, Département Génie Biologique, Bd Dr Petitjean, 21078 Dijon Cedex, France

4 Klinik für Allgemein-, Visceral- und Transplantations-Chirurgie, Charité-Campus Virchow, Augustenburger Platz 1, 13353 Berlin, Germany

For all author emails, please log on.

BMC Microbiology 2008, 8:91  doi:10.1186/1471-2180-8-91

Published: 10 June 2008

Abstract

Background

Pathogenic mycobacteria such as M. tuberculosis, M. bovis or M. leprae are characterised by their extremely slow growth rate which plays an important role in mycobacterial virulence and eradication of the bacteria. Various limiting factors influence the generation time of mycobacteria, and the mycobacterial DNA-binding protein 1 (MDP1) has also been implicated in growth regulation. Our strategy to investigate the role of MDP1 in mycobacterial growth consisted in the generation and characterisation of a M. bovis BCG derivative expressing a MDP1-antisense gene.

Results

The expression rate of the MDP1 protein in the recombinant M. bovis BCG containing the MDP1-antisense plasmid was reduced by about 50% compared to the reference strain M. bovis BCG containing the empty vector. In comparison to this reference strain, the recombinant M. bovis BCG grew faster in broth culture and reached higher cell masses in stationary phase. Likewise its intracellular growth in mouse and human macrophages was ameliorated. Bacterial clumping in broth culture was reduced by the antisense plasmid. The antisense plasmid increased the susceptibility of the bacteria towards Ampicillin. 2-D protein gels of bacteria maintained under oxygen-poor conditions demonstrated a reduction in the number and the intensity of many protein spots in the antisense strain compared to the reference strain.

Conclusion

The MDP1 protein has a major impact on various growth characteristics of M. bovis BCG. It plays an important role in virulence-related traits such as aggregate formation and intracellular multiplication. Its impact on the protein expression in a low-oxygen atmosphere indicates a role in the adaptation to the hypoxic conditions present in the granuloma.