PstS-1, the 38-kDa Mycobacterium tuberculosis Glycoprotein, is an Adhesin, Which Binds the Macrophage Mannose Receptor and Promotes Phagocytosis
Por:
Esparza, M, Palomares, B, Garcia, T, Espinosa, P, Zenteno, E, Mancilla, R
Publicada:
1 ene 2015
Categoría:
Immunology
Resumen:
Mycobacterium tuberculosis, the primary causative agent of tuberculosis,
infects macrophages and transforms the hostile intracellular environment
into a permissive niche. M.tuberculosis infects macrophages using a
variety of microbial ligand/cell receptor systems. In this study,
binding assays with biotin-labelled mycobacterial cell wall proteins
revealed five Concanavalin A-reactive proteins that bind macrophages.
Among these proteins, we identified PstS-1, a 38-kDa M.tuberculosis
mannosylated glycolipoprotein, and characterized it as an adhesin.
Inhibition assays with mannan and immunoprecipitation demonstrated that
PstS-1 binds the mannose receptor. We purified PstS-1 to 95.9% purity
using ion exchange chromatography. The presence of mannose in purified
PstS-1 was demonstrated by Concanavalin A interaction, which was
abolished in the presence of sodium m-periodate and -D-mannosidase. Gas
chromatography revealed that purified PstS-1 contained 1% of
carbohydrates by weight, which was mainly mannose. Finally, we used
fluorescent microbeads coated with purified PstS-1 in phagocytosis
assays and discovered that microbead uptake was inhibited by the
pre-incubation of cells with GlcNAc, mannan and -methyl mannoside. The
interaction of PstS-1 coated beads with the mannose receptor was
confirmed by confocal colocalization studies that showed high Pearson
and Manders's colocalization coefficients. Our findings contribute to a
better understanding of the strategies M.tuberculosis uses to infect
host cells, the critical first step in the pathogenesis of tuberculosis.
Filiaciones:
Esparza, M:
Univ Nacl Autonoma Mexico, Inst Invest Biomed, Dept Inmunol, Mexico City 04510, DF, Mexico
Palomares, B:
Univ Nacl Autonoma Mexico, Inst Invest Biomed, Dept Inmunol, Mexico City 04510, DF, Mexico
Garcia, T:
Univ Nacl Autonoma Mexico, Inst Invest Biomed, Dept Inmunol, Mexico City 04510, DF, Mexico
Espinosa, P:
Univ Nacl Autonoma Mexico, Inst Invest Biomed, Dept Inmunol, Mexico City 04510, DF, Mexico
Zenteno, E:
Univ Nacl Autonoma Mexico, Fac Med, Dept Bioquim, Mexico City 04510, DF, Mexico
Mancilla, R:
Univ Nacl Autonoma Mexico, Inst Invest Biomed, Dept Inmunol, Mexico City 04510, DF, Mexico
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