Structural Characterization of a Specific Glycopeptidolipid Containing a Novel N -Acyl-Deoxy Sugar from Mycobacterium intracellulare Serotype 7 and Genetic Analysis of Its Glycosylation Pathway

Abstract

The nontuberculous Mycobacterium avium-Mycobacterium intracellulare complex (MAC) is distributed ubiquitously in the environment and is an important cause of respiratory and lymphatic disease in humans and animals. These species produce polar glycopeptidolipids (GPLs), and of particular interest is their serotype-specific antigenicity. Structurally, GPLs contain an N-acylated tetrapeptide-amino alcohol core that is glycosylated at the C terminal with 3,4-di-O-methyl rhamnose and at the D-allo-threonine with a 6-deoxy-talose. This serotype nonspecific GPL is found in all MAC species. The serotype-specific GPLs are further glycosylated with a variable haptenic oligosaccharide at 6-deoxy-talose. At present, 31 distinct serotype-specific GPLs have been identified on the basis of oligosaccharide composition, and the complete structures of 14 serotype-specific GPLs have been defined. It is considered that the modification of the GPL structure plays an important role in bacterial physiology, pathogenesis, and host immune responses. In this study, we defined the complete structure of a novel serotype 7 GPL that has a unique terminal amido sugar. The main molecular mass is 1,874, and attached to the tetrapeptide-amino alcohol core is the serotype 7-specific oligosaccharide unit of 4-2-hydroxypropanoyl-amido-4,6-dideoxy-2-O-methyl-␤-hexose- (

Identification and Characterization of Two Novel Methyltransferase Genes That Determine the Serotype 12-Specific Structure of Glycopeptidolipids of Mycobacterium intracellulare

“…In a previous study, we determined the complete structure of the GPL derived from M. intracellulare serotype 7 and characterized the serotype 7-specific gene cluster for GPL synthesis (10). The structure of serotype 7 GPL closely resembles that of serotype 12 GPL, except for O methylation (Fig.…”

“…GPL 7 and GPL 12 were purified from M. intracellulare NF 027 and NF 103, respectively. The preparation of GPLs was performed as described previously (10,15,17). Briefly, each strain was grown in Middlebrook 7H9 broth (Difco Laboratories, Detroit, MI) with 0.5% glycerol and 10% Middlebrook oleic acid-albumin-dextrose-catalase enrichment (Difco Laboratories) at 37°C for 2 to 3 weeks.…”

“…In the present study, we determined the nucleotide sequence of the serotype 12-specific gene cluster involved in the glycosylation of the GPL and characterized two novel open reading frames (ORFs) encoding O-methyltransferases that determine the difference of serotype 12 GPL from serotype 7 GPL. (10). Briefly, genomic DNA of M. intracellulare NF 103 was prepared by mechanical disruption of bacterial cells in phosphate-buffered saline containing 50 mM EDTA, followed by phenol-chloroform extraction and precipitation with ethanol.…”

“…In the serotype-specific GPLs, a haptenic OSE is linked with the 6-d-Tal residue. To date, 31 distinct serotype-specific polar GPLs have been identified biochemically; the complete structures of GPLs are partly defined for serotype 1 to 4,7,8,9,12,14,17,19 to 21,25,and 26 GPLs (7,10). On the other hand, it has been reported that serotype-specific GPLs participate in pathogenesis and immunomodulation in the host (2,13).…”

Nontuberculous Mycobacterium Infections in Rheumatoid Arthritis Patients

“…The chemical structure of GPL consists of a common GPL core, with the different oligossacharide (polar GPL) moieties linked at the Thr substituent of the core. There are 31 distinct GPL serotypes, of which the complete structures of 14 have been identified (Aspinall et al, 1995;Brennan & Nikaido, 1995;Fujiwara et al, 2007;Kitada et al, 2005). Kitada et al (2008) established an EIA kit for the serological diagnosis of MAC-PD that is based on the levels of serum IgA antibody to the GPL core.…”