title: Lipoarabinomannan biosynthesis in Corynebacterineae: the interplay of two α(1→2)-mannopyranosyltransferases MptC and MptD in mannan branching.
abstract: Lipomannan (LM) and lipoarabinomannan (LAM) are key Corynebacterineae glycoconjugates that are integral components of the mycobacterial cell wall, and are potent immunomodulators during infection. LAM is a complex heteropolysaccharide synthesized by an array of essential glycosyltransferase family C (GT-C) members, which represent potential drug targets. Herein, we have identified and characterized two open reading frames from Corynebacterium glutamicum that encode for putative GT-Cs. Deletion of NCgl2100 and NCgl2097 in C. glutamicum demonstrated their role in the biosynthesis of the branching α(1→2)-Manp residues found in LM and LAM. In addition, utilizing a chemically defined nonasaccharide acceptor, azidoethyl 6-O-benzyl-α-D-mannopyranosyl-(1→6)-[α-D-mannopyranosyl-(1→6)](7) -D-mannopyranoside, and the glycosyl donor C(50) -polyprenol-phosphate-[(14) C]-mannose with membranes prepared from different C. glutamicum mutant strains, we have shown that both NCgl2100 and NCgl2097 encode for novel α(1→2)-mannopyranosyltransferases, which we have termed MptC and MptD respectively. Complementation studies and in vitro assays also identified Rv2181 as a homologue of Cg-MptC in Mycobacterium tuberculosis. Finally, we investigated the ability of LM and LAM from C. glutamicum, and C. glutamicumΔmptC and C. glutamicumΔmptD mutants, to activate Toll-like receptor 2. Overall, our study enhances our understanding of complex lipoglycan biosynthesis in Corynebacterineae and sheds further light on the structural and functional relationship of these classes of polysaccharides.
authors: School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors: Arun K
authors: AK
authors: Mishra
authors: Karin
authors: K
authors: Krumbach
authors: Doris
authors: D
authors: Rittmann
authors: Ben
authors: B
authors: Appelmelk
authors: Vibha
authors: V
authors: Pathak
authors: Ashish K
authors: AK
authors: Pathak
authors: Jerome
authors: J
authors: Nigou
authors: Jeroen
authors: J
authors: Geurtsen
authors: Lothar
authors: L
authors: Eggeling
authors: Gurdyal S
authors: GS
authors: Besra
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways; D048230:Corynebacterium glutamicum / Q000737:chemistry / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000096:biosynthesis* / Q000737:chemistry; D008351:Mannans / Q000378:metabolism*; D015394:Molecular Structure; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D008351:Mannans; C050016:lipoarabinomannan; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System