A GMC Oxidoreductase Homologue Is Required for Acetylation of Glycopeptidolipid in Mycobacterium smegmatis

The Mycobacterium tuberculosis Rv3409c gene is required for modulation of the Toll-like receptor 2 (TLR-2) signaling response in infected macrophages. Although each is annotated as encoding a cholesterol oxidase, neither Rv3409c nor its ortholog MSMEG1604 is required for the metabolism of cholesterol in mycobacteria. Here we report that a unique lipid, L1334, accumulates in a MSMEG1604 transposon mutant in the Mycobacterium smegmatis cell envelope. L1334 is a polar glycopeptidolipid that is hyperrhamnosylated and in which the 6-deoxytalose moiety is not acetylated. The alteration of L1334 acetylation is consistent with a reduced level of interference with TLR-2 signaling in mutant infected macrophages.