title: Lipoamide dehydrogenase mediates retention of coronin-1 on BCG vacuoles, leading to arrest in phagosome maturation.
abstract: Mycobacterium tuberculosis evades the innate antimicrobial defenses of macrophages by inhibiting the maturation of its phagosome to a bactericidal phagolysosome. Despite intense studies of the mycobacterial phagosome, the mechanism of mycobacterial persistence dependent on prolonged phagosomal retention of the coat protein coronin-1 is still unclear. The present study demonstrated that several mycobacterial proteins traffic intracellularly in M. bovis BCG-infected cells and that one of them, with an apparent subunit size of M(r) 50,000, actively retains coronin-1 on the phagosomal membrane. This protein was initially termed coronin-interacting protein (CIP)50 and was shown to be also expressed by M. tuberculosis but not by the non-pathogenic species M. smegmatis. Cell-free system experiments using a GST-coronin-1 construct showed that binding of CIP50 to coronin-1 required cholesterol. Thereafter, mass spectrometry sequencing identified mycobacterial lipoamide dehydrogenase C (LpdC) as a coronin-1 binding protein. M. smegmatis over-expressing Mtb LpdC protein acquired the capacity to maintain coronin-1 on the phagosomal membrane and this prolonged its survival within the macrophage. Importantly, IFNgamma-induced phagolysosome fusion in cells infected with BCG resulted in the dissociation of the LpdC-coronin-1 complex by a mechanism dependent, at least in part, on IFNgamma-induced LRG-47 expression. These findings provide further support for the relevance of the LpdC-coronin-1 interaction in phagosome maturation arrest.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of British Columbia, Vancouver Costal Health Institute, Vancouver, British Columbia, V5Z 3J5, Canada.
authors.forename: Ala-Eddine
authors.initials: AE
authors.lastname: Deghmane
authors.forename: Hafid
authors.initials: H
authors.lastname: Soualhine
authors.forename: Hafid
authors.initials: H
authors.lastname: Soulhine
authors.forename: Horacio
authors.initials: H
authors.lastname: Bach
authors.forename: Khalid
authors.initials: K
authors.lastname: Sendide
authors.forename: Saotomo
authors.initials: S
authors.lastname: Itoh
authors.forename: Andrea
authors.initials: A
authors.lastname: Tam
authors.forename: Sanaa
authors.initials: S
authors.lastname: Noubir
authors.forename: Amina
authors.initials: A
authors.lastname: Talal
authors.forename: Raymond
authors.initials: R
authors.lastname: Lo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Toyoshima
authors.forename: Yossef
authors.initials: Y
authors.lastname: Av-Gay
authors.forename: Zakaria
authors.initials: Z
authors.lastname: Hmama
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D008058:Dihydrolipoamide Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000382:microbiology / Q000648:ultrastructure; D051379:Mice; D050296:Microbial Viability / Q000187:drug effects; D008840:Microfilament Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009163:Mycobacterium bovis / Q000187:drug effects / Q000201:enzymology*; D020102:Mycobacterium smegmatis; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology*; D010588:Phagosomes / Q000187:drug effects / Q000382:microbiology* / Q000648:ultrastructure; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D014617:Vacuoles / Q000187:drug effects / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; C096000:Ifi1 protein, mouse; D008840:Microfilament Proteins; C072061:coronin proteins; D007371:Interferon-gamma; D002784:Cholesterol; D008058:Dihydrolipoamide Dehydrogenase; D019204:GTP-Binding Proteins