title: 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.affiliation: Institut für Medizinische Mikrobiologie, Universität Zürich, Gloriastrasse 32, CH-8006 Zurich, Switzerland.
authors.forename: Silvana K
authors.initials: SK
authors.lastname: Rampini
authors.affiliation: Institut für Medizinische Mikrobiologie, Universität Zürich, Gloriastrasse 32, CH-8006 Zurich, Switzerland.
authors.forename: Petra
authors.initials: P
authors.lastname: Selchow
authors.affiliation: Molecular Infection Biology, Research Center Borstel, D-23845 Borstel, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Keller
authors.affiliation: Molecular Infection Biology, Research Center Borstel, D-23845 Borstel, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Ehlers
authors.affiliation: Nationales Zentrum für Mykobakterien, Gloriastrasse 30, CH-8006 Zurich, Switzerland.|Institut für Medizinische Mikrobiologie, Universität Zürich, Gloriastrasse 32, CH-8006 Zurich, Switzerland.
authors.forename: Erik C
authors.initials: EC
authors.lastname: Böttger
authors.affiliation: Nationales Zentrum für Mykobakterien, Gloriastrasse 30, CH-8006 Zurich, Switzerland.|Institut für Medizinische Mikrobiologie, Universität Zürich, Gloriastrasse 32, CH-8006 Zurich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Sander
mesh_terms: D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D006863:Hydrogen-Ion Concentration; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D010588:Phagosomes / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D051195:Toll-Like Receptor 2 / Q000276:immunology* / Q000378:metabolism; D014376:Tuberculosis / Q000276:immunology / Q000382:microbiology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014774:Virulence; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D016282:Aspartic Acid Endopeptidases; D001426:Bacterial Proteins; D051907:Lysosomal Membrane Proteins; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1; C095652:signal peptidase II