Inactivation of Corynebacterium glutamicum NCg10452 and the role of MgtA in the biosynthesis of a novel mannosylated glycolipid involved in-lipomannan biosynthesis

Tatituri, Raju, Dover, Lynn, Nigou, Jerome, Illarionov, Petr A., Gilleron, Martine, Hitchen, Paul, Krumbach, Karin, Morris, Howard, Spencer, Neil, Dell, Anne, Eggeling, Lothar and Besra, Gurdyal (2007) Inactivation of Corynebacterium glutamicum NCg10452 and the role of MgtA in the biosynthesis of a novel mannosylated glycolipid involved in-lipomannan biosynthesis. The Journal of Biological Chemistry, 282. pp. 4561-4572. ISSN 0021-9258

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Official URL: http://dx.doi.org/10.1074/jbc.M608695200

Abstract

Mycobacterium tuberculosis PimB has been demonstrated to catalyze the addition of a mannose residue from GDP-mannose to a monoacylated phosphatidyl-myo-inositol mannoside (Ac1PIM1) to generate Ac1PIM2. Herein, we describe the disruption of its probable orthologue Cg-pimB and the chemical analysis of glycolipids and lipoglycans isolated from wild type Corynebacterium glutamicum and the C. glutamicum::pimB mutant. Following a careful analysis, two related glycolipids, Gl-A and Gl-X, were found in the parent strain, but Gl-X was absent from the mutant. The biosynthesis of Gl-X was restored in the mutant by complementation with either Cg-pimB or Mt-pimB. Subsequent chemical analyses established Gl-X as 1,2-di-O-C16/C18:1-(α-D-mannopyranosyl)-(1→4)-(α-D-glucopyranosyluronic acid)-(1→3)-glycerol (ManGlcAGroAc2) and Gl-A as the precursor, GlcAGroAc2. In addition, C. glutamicum::pimB was still able to produce Ac1PIM2, suggesting that Cg-PimB catalyzes the synthesis of ManGlcAGroAc2 from GlcAGroAc2. Isolation of lipoglycans from C. glutamicum led to the identification of two related lipoglycans. The larger lipoglycan possessed a lipoarabinomannan-like structure, whereas the smaller lipoglycan was similar to lipomannan (LM). The absence of ManGlcA-GroAc2 in C. glutamicum::pimB led to a severe reduction in LM. These results suggested that ManGlcAGroAc2 was further extended to an LM-like molecule. Complementation of C. glutamicum::pimB with Cg-pimB and Mt-pimB led to the restoration of LM biosynthesis. As a result, Cg-PimB, which we have assigned as MgtA, is now clearly defined as a GDP-mannose-dependent α-mannosyltransferase from our in vitro analyses and is involved in the biosynthesis of ManGlcAGroAc2.

Item Type: Article
Subjects: C700 Molecular Biology, Biophysics and Biochemistry
Department: Faculties > Health and Life Sciences > School of Life Sciences > Applied Sciences
Depositing User: EPrints Services
Date Deposited: 18 Dec 2008 14:14
Last Modified: 10 Aug 2015 11:47
URI: http://nrl.northumbria.ac.uk/id/eprint/624

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