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.
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-beta-hexose-(1-->3)-alpha-l-rhamnose-(1-->3)-alpha-l-rhamnose-(1-->3)-alpha-l-rhamnose-(1-->2)-alpha-l-6-deoxy-talose. Moreover, we isolated and characterized the serotype 7-specific gene cluster involved in glycosylation of the oligosaccharide. Nine open reading frames (ORFs) were observed in the cluster. Based on the sequence homology, the ORFs are thought to participate in the biosynthesis of the serotype 7 GPL.
Fujiwara
Nagatoshi
N
Department of Host Defense, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Osaka 545-8585, Japan. fujiwara@med.osaka-cu.ac.jp
Nakata
Noboru
N
Maeda
Shinji
S
Naka
Takashi
T
Doe
Matsumi
M
Yano
Ikuya
I
Kobayashi
Kazuo
K
D002240:Carbohydrate Sequence; D002849:Chromatography, Gas; D003837:Deoxy Sugars / Q000737:chemistry*; D005798:Genes, Bacterial; D006017:Glycolipids / Q000032:analysis* / Q000737:chemistry; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D015269:Mycobacterium avium Complex / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D012703:Serotyping; D021241:Spectrometry, Mass, Electrospray Ionization; D016339:Spectrometry, Mass, Fast Atom Bombardment
D003837:Deoxy Sugars; D006017:Glycolipids