title: Structure and host recognition of serotype 13 glycopeptidolipid from Mycobacterium intracellulare.
abstract: The Mycobacterium avium-M. intracellulare complex (MAIC) is divided into 28 serotypes by a species-specific glycopeptidolipid (GPL). Previously, we clarified the structures of serotype 7 GPL and two methyltransferase genes (orfA and orfB) in serotype 12 GPL. This study elucidated the chemical structure, biosynthesis gene, and host innate immune response of serotype 13 GPL. The oligosaccharide (OSE) structure of serotype 13 GPL was determined to be 4-2'-hydroxypropanoyl-amido-4,6-dideoxy-β-hexose-(1 → 3)-4-O-methyl-α-L-rhamnose-(1 → 3)-α-L-rhamnose-(1 → 3)-α-L-rhamnose-(1 → 2)-α-L-6-deoxy-talose by using chromatography, mass spectrometry, and nuclear magnetic resonance (NMR) analyses. The structure of the serotype 13 GPL was different from those of serotype 7 and 12 GPLs only in O-methylations. We found a relationship between the structure and biosynthesis gene cluster. M. intracellulare serotypes 12 and 13 have a 1.95-kb orfA-orfB gene responsible for 3-O-methylation at the terminal hexose, orfB, and 4-O-methylation at the rhamnose next to the terminal hexose, orfA. The serotype 13 orfB had a nonfunctional one-base missense mutation that modifies serotype 12 GPL to serotype 13 GPL. Moreover, the native serotype 13 GPL was multiacetylated and recognized via Toll-like receptor 2. The findings presented here imply that serotypes 7, 12, and 13 are phylogenetically related and confirm that acetylation of the GPL is necessary for host recognition. This study will promote better understanding of the structure-function relationships of GPLs and may open a new avenue for the prevention of MAIC infections.
authors.affiliation: Department of Bacteriology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Naka
authors.forename: Noboru
authors.initials: N
authors.lastname: Nakata
authors.forename: Shinji
authors.initials: S
authors.lastname: Maeda
authors.forename: Reina
authors.initials: R
authors.lastname: Yamamoto
authors.forename: Matsumi
authors.initials: M
authors.lastname: Doe
authors.forename: Seiko
authors.initials: S
authors.lastname: Mizuno
authors.forename: Mamiko
authors.initials: M
authors.lastname: Niki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Ogura
authors.forename: Masahiko
authors.initials: M
authors.lastname: Makino
authors.forename: Nagatoshi
authors.initials: N
authors.lastname: Fujiwara
mesh_terms: D000107:Acetylation; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002240:Carbohydrate Sequence; D002460:Cell Line; D006017:Glycolipids / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006020:Glycopeptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D058507:Host Specificity; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D015269:Mycobacterium avium Complex / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000502:physiology*; D015270:Mycobacterium avium-intracellulare Infection / Q000378:metabolism / Q000382:microbiology*; D013045:Species Specificity; D051195:Toll-Like Receptor 2 / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006017:Glycolipids; D006020:Glycopeptides; D051195:Toll-Like Receptor 2; C010762:peptidoglycolipids