A glycosylated lipooctapeptide promotes uptake and growth of Mycobacterium abscessus in the host.

Abstract

Pathogenic mycobacteria produce a wide array of lipids which participate in host cell interactions and virulence. While some of these are conserved across all mycobacteria, others, like glycopeptidolipids (GPL), are restricted to a few species. Mycobacterium abscessus, an emerging rapid-growing pathogen, transitions from a smooth to a virulent rough variant upon the loss of surface GPL. Here, we discovered that M. abscessus and phylogenetically-close species harbor a second GPL-related locus, comprising two adjacent non-ribosomal peptide synthetase genes, MAB_4690c and MAB_4691c. A MAB_4690c deletion mutant (ΔMAB_4690c) failed to produce a yet undescribed lipid, designated GL8P for glycosylated lipooctapeptide, sharing an acylated octapeptide core adorned by mono or di-O-rhamnosyl substituents. ΔMAB_4690c exhibited impaired uptake and survival in THP-1 cells and was attenuated in mice. Importantly, GL8P elicited a strong humoral response in patients infected with M. abscessus. These results highlight the role of GL8P in the pathophysiology of infection by rough M. abscessus and suggest its potential as a selective marker for M. abscessus infections.