title: LosA, a key glycosyltransferase involved in the biosynthesis of a novel family of glycosylated acyltrehalose lipooligosaccharides from Mycobacterium marinum.
abstract: Members of the genus Mycobacterium are characterized by cell envelopes rich in unusual free lipids, interacting with a covalently anchored mycolyl-arabinogalactan matrix. Previous studies have shown that Mycobacterium marinum produces large amounts of a diacylglycosylphenolphthiocerol, "phenolic" glycolipid. When cultivated on liquid Sauton medium, traces of a polar lipooligosaccharide (LOS) glycolipid antigen were also previously indicated. In this study, it was found that growth of the type strain of M. marinum on solid Sauton or Middlebrook 7H10 agar gave substantial, but different, amounts of a family of four major trehalose-based LOSs. The core pentasaccharide LOS-I was a rhamnosyl diglucosyl-acylated trehalose. The heptasaccharide, LOS-II, was derived from LOS-I by adding xylose accompanied by a novel sugar (X); repeated addition of this sugar unit X gave the octasaccharide LOS-III. LOS-IV has a decasaccharide component with two additional unusual sugar units, YZ. In a recent study (Alexander, D. C., Jones, J. R., Tan, T., Chen, J. M., and Liu, J. (2004) J. Biol. Chem. 279, 18824-18833), chromatographically similar glycolipids were assigned to the family of phosphatidylinositol mannosides (PIMs) and a "PimF" (Rv1500) glycosyltransferase implicated in the conversion of a supposed "PIM5" to a "PIM7." The present study indicates that these putative PIMs are in fact members of the phosphorus-free LOS family of glycolipids and that the protein product of Rv1500, which we have now termed LosA, is a glycosyltransferase involved in transferring sugars to LOS-III to form LOS-IV of M. marinum.
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT.
authors.forename: Adeline
authors.initials: A
authors.lastname: Burguière
authors.forename: Paul G
authors.initials: PG
authors.lastname: Hitchen
authors.forename: Lynn G
authors.initials: LG
authors.lastname: Dover
authors.forename: Laurent
authors.initials: L
authors.lastname: Kremer
authors.forename: Malin
authors.initials: M
authors.lastname: Ridell
authors.forename: David C
authors.initials: DC
authors.lastname: Alexander
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Howard R
authors.initials: HR
authors.lastname: Morris
authors.forename: David E
authors.initials: DE
authors.lastname: Minnikin
authors.forename: Anne
authors.initials: A
authors.lastname: Dell
authors.forename: Gurdyal S
authors.initials: GS
authors.lastname: Besra
mesh_terms: D001483:Base Sequence; D002240:Carbohydrate Sequence; D002855:Chromatography, Thin Layer; D017931:DNA Primers; D016695:Glycosyltransferases / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000096:biosynthesis* / Q000737:chemistry; D008969:Molecular Sequence Data; D019910:Mycobacterium marinum / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D017931:DNA Primers; D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D016695:Glycosyltransferases