Open AccessIdentification of the M ycobacterium tuberculosis protein PE‐PGRS62 as a novel effector that functions to block phagosome maturation and inhibit iNOS expression
Author(s) -
Thi Emily P.,
Hong Chris Joon Ho,
Sanghera Gaganjit,
Reiner Neil E.
Publication year - 2013
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/cmi.12073
Subject(s) - biology , mycobacterium smegmatis , phagosome , microbiology and biotechnology , mycobacterium marinum , complementation , mutant , effector , virulence , mycobacterium tuberculosis , mycobacterium , phagocytosis , gene , bacteria , tuberculosis , genetics , medicine , pathology
Summary Using a genetic screen in yeast we found that M ycobacterium tuberculosis PE‐PGRS62 was capable of disrupting yeast vacuolar protein sorting, suggesting effects on endosomal trafficking. To study the impact of PE‐PGRS62 on macrophage function, we infected murine macrophages with M ycobacterium smegmatis expressing PE‐PGRS62 . Infected cells displayed phagosome maturation arrest. Phagosomes acquired R ab5, but displayed a significant defect in R ab7 and LAMP ‐1 acquisition. Macrophages infected with M . smegmatis expressing PE‐PGRS62 also expressed two‐ to threefold less iNOS protein when compared with cells infected with wild‐type bacteria. Consistent with this, cells infected with a M ycobacterium marinum transposon mutant for the PE‐PGRS62 orthologue showed greater iNOS protein expression when compared to cells infected with wild‐type organisms. Complementation restored the ability of the mutant to inhibit iNOS expression. No differences in iNOS transcript levels were observed, suggesting that PE‐PGRS62 effects on iNOS expression occurred post‐transcriptionally. Marked differences in colony morphology were also seen in M . smegmatis expressing PE‐PGRS62 and in the M . marinum transposon mutant,suggesting that PE‐PGRS62 may affect cell wall composition. These findings suggest that PE‐PGRS62 supports virulence via inhibition of phagosome maturation and iNOS expression, and these phenotypes may be linked to effects on bacterial cell wall composition.