title: Structural characterization and functional properties of a novel lipomannan variant isolated from a Corynebacterium glutamicum pimB' mutant.
abstract: The genus Corynebacterium is part of the phylogenetic group nocardioform actinomycetes, which also includes the genus Mycobacterium. Members of this phylogenetic group have a characteristic cell envelope structure, which is dominated by complex lipids and amongst these, lipoglycans are of particular interest. The disruption of NCgl2106 in C. glutamicum resulted in a mutant devoid of monoacylated phosphatidyl-myo-inositol dimannoside (Ac(1)PIM(2)) resulting in the accumulation of Ac(1)PIM(1) and cessation of phosphatidyl-myo-inositol (PI) based lipomannan (Cg-LM, now also termed 'Cg-LM-A') and lipoarabinomannan (Cg-LAM) biosynthesis. Interestingly, SDS-analysis of the lipoglycan fraction from the mutant revealed the synthesis of a single novel lipoglycan, now termed 'Cg-LM-B'. Further chemical analyses established the lipoglycan possessed an alpha-D: -glucopyranosyluronic acid-(1 --> 3)-glycerol (GlcAGroAc(2)) based anchor which was then further glycosylated by 8-22 mannose residues, with Man(12-20)GlcAGroAC(2) molecular species being the most abundant, to form a novel lipomannan structure (Cg-LM-B). The deletion of NCgl2106 in C. glutamicum has now provided a useful strain, in addition with a deletion mutant of NCgl0452 in C. glutamicum for the purification of Cg-LM-A and Cg-LM-B. Interestingly, both Cg-LM species induced a similar production of TNF-alpha by a human macrophage cell line suggesting that the phospho-myo-inositol residue of the PI-anchor does not play a key role in lipoglycan pro-inflammatory activity.
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Mishra
authors.forename: Christina
authors.initials: C
authors.lastname: Klein
authors.forename: Sudagar S
authors.initials: SS
authors.lastname: Gurcha
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Alderwick
authors.forename: Ponnusamy
authors.initials: P
authors.lastname: Babu
authors.forename: Paul G
authors.initials: PG
authors.lastname: Hitchen
authors.forename: Howard R
authors.initials: HR
authors.lastname: Morris
authors.forename: Anne
authors.initials: A
authors.lastname: Dell
authors.forename: Gurdyal S
authors.initials: GS
authors.lastname: Besra
authors.forename: Lothar
authors.initials: L
authors.lastname: Eggeling
mesh_terms: D053898:Biosynthetic Pathways; D002460:Cell Line; D048230:Corynebacterium glutamicum / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008055:Lipids / Q000737:chemistry / Q000235:genetics; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D008264:Macrophages / Q000276:immunology; D013058:Mass Spectrometry; D009154:Mutation; D010716:Phosphatidylinositols / Q000235:genetics* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D008055:Lipids; D008070:Lipopolysaccharides; D010716:Phosphatidylinositols; D014409:Tumor Necrosis Factor-alpha; C064351:lipomannan; C054977:phosphatidylinositol dimannoside