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Overexpression of Mycobacterium tuberculosis manB , a phosphomannomutase that increases phosphatidylinositol mannoside biosynthesis in Mycobacterium smegmatis and mycobacterial association with human macrophages
Author(s) -
McCarthy Travis R.,
Torrelles Jordi B.,
MacFarlane Amanda Shearer,
Katawczik Melanie,
Kutzbach Beth,
DesJardin Lucy E.,
Clegg Steven,
Goldberg Joanna B.,
Schlesinger Larry S.
Publication year - 2005
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2005.04862.x
Subject(s) - biology , mannose , mycobacterium smegmatis , lipoarabinomannan , microbiology and biotechnology , mycobacterium tuberculosis , phosphatidylinositol , complementation , mannose receptor , mycobacterium , phosphoglucomutase , mycobacterium kansasii , macrophage , biochemistry , tuberculosis , gene , enzyme , in vitro , bacteria , signal transduction , phenotype , genetics , medicine , pathology
Summary Mycobacterium tuberculosis ( M. tb ) pathogenesis involves the interaction between the mycobacterial cell envelope and host macrophage, a process mediated, in part, by binding of the mannose caps of M. tb lipoarabinomannan (ManLAM) to the macrophage mannose receptor (MR). A presumed critical step in the biosynthesis of ManLAM, and other mannose‐containing glycoconjugates, is the conversion of mannose‐6‐phosphate to mannose‐1‐phosphate, by a phosphomannomutase (PMM), to produce GDP‐mannose, the primary mannose‐donor in mycobacteria. We have identified four M. tb H37Rv genes with similarity to known PMMs. Using in vivo complementation of PMM and phosphoglucomutase (PGM) deficient strains of Pseudomonas aeruginosa , and an in vitro enzyme assay, we have identified both PMM and PGM activity from one of these genes, Rv3257c (Mt manB ). Mt manB overexpression in M. smegmatis produced increased levels of LAM, lipomannan, and phosphatidylinositol mannosides (PIMs) compared with control strains and led to a 13.3 ± 3.9‐fold greater association of mycobacteria with human macrophages, in a mannan‐inhibitable fashion. This increased association was mediated by the overproduction of higher order PIMs that possess mannose cap structures. We conclude that Mt manB encodes a functional PMM involved in the biosynthesis of mannosylated lipoglycans that participate in the association of mycobacteria with macrophage phagocytic receptors.