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


Rampini, S K; Selchow, P; Keller, C; Ehlers, S; Böttger, E C; Sander, P (2008). LspA inactivation in Mycobacterium tuberculosis results in attenuation without affecting phagosome maturation arrest. Microbiology, 154(Pt 10):2991-3001.

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.

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.

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16 citations in Web of Science®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Medical Microbiology
04 Faculty of Medicine > University Hospital Zurich > Clinic for Infectious Diseases
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2008
Deposited On:30 Oct 2008 14:16
Last Modified:05 Apr 2016 12:29
Publisher:Society for General Microbiology
ISSN:1350-0872
Publisher DOI:10.1099/mic.0.2008/018895-0
PubMed ID:18832305

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