LspA inactivation in Mycobacterium tuberculosis results in attenuation without affecting phagosome maturation arrest.

Abstract

The success of Mycobacterium tuberculosis depends on its ability to survive within host macrophages. Here, M. tuberculosis avoids the acidic, hydrolytically competent environment of the phagolysosome by arresting phagosome maturation. Having shown previously that a M. tuberculosis mutant deficient in lipoprotein signal peptidase (LspA) is strongly attenuated in vivo in a mouse model of infection, we now studied putative mechanisms involved in attenuation of the lspA : : aph mutant at a cellular level. In this work we investigated the ability of the mutant to interfere with two host defence mechanisms, i.e. Toll-like receptor (TLR)2-dependent immune response and phagosome maturation. While mycobacterial lipoproteins have been reported to trigger a TLR2 signalling pathway critical for innate immune responses, we found that growth control of the lspA : : aph mutant was independent of TLR2. In addition, the lspA : : aph mutant arrested phagosome maturation to an extent similar to that of the wild-type, as measured by lysosomal-associated membrane protein 1 (LAMP1) co-localization and intraphagosomal pH. These observations demonstrate severe attenuation even in the presence of arrested phagosome maturation, and point to a role for the early phagosome in growth restriction of the M. tuberculosis lspA mutant.

• Authors: Silvana K Rampini, Petra Selchow, Christine Keller, Stefan Ehlers, Erik C Böttger, Peter Sander
• Journal: Microbiology (Reading, England) (Microbiology (Reading)) Vol. 154 Issue Pt 10 Pg. 2991-3001 (Oct 2008) ISSN: 1350-0872 [Print] England
• PMID: 18832305 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• Lamp1 protein, mouse
• Lysosome-Associated Membrane Glycoproteins
• Toll-Like Receptor 2
• Tumor Necrosis Factor-alpha
• Aspartic Acid Endopeptidases
• signal peptidase II

Topics

• Animals
• Aspartic Acid Endopeptidases (genetics, immunology, metabolism)
• Bacterial Proteins (genetics, immunology, metabolism)
• Cells, Cultured
• Female
• Hydrogen-Ion Concentration
• Lysosome-Associated Membrane Glycoproteins (metabolism)
• Macrophages (immunology, metabolism, microbiology)
• Mice
• Mice, Inbred BALB C
• Mice, Inbred C57BL
• Mycobacterium tuberculosis (enzymology, genetics, immunology, pathogenicity)
• Phagosomes (immunology, metabolism, microbiology)
• Toll-Like Receptor 2 (immunology, metabolism)
• Tuberculosis (immunology, microbiology)
• Tumor Necrosis Factor-alpha (metabolism)
• Virulence