Inactivation of Corynebacterium glutamicum NCgl0452 and the Role of MgtA in the Biosynthesis of a Novel Mannosylated Glycolipid Involved in Lipomannan Biosynthesis

• Published in: The Journal of biological chemistry Vol. 282; no. 7; pp. 4561 - 4572
• Main Authors: Tatituri, Raju V V, Illarionov, Petr A, Dover, Lynn G, Nigou, Jerome, Gilleron, Martine, Hitchen, Paul, Krumbach, Karin, Morris, Howard R, Spencer, Neil, Dell, Anne, Eggeling, Lothar, Besra, Gurdyal S
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 16-02-2007
• Subjects: Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Corynebacterium glutamicum; Corynebacterium glutamicum - enzymology; Corynebacterium glutamicum - genetics; Gene Deletion; Genetic Complementation Test; Lipopolysaccharides - biosynthesis; Mannosyltransferases - genetics; Mannosyltransferases - metabolism; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Mycobacterium tuberculosis; Mycobacterium tuberculosis - enzymology; Mycobacterium tuberculosis - genetics; Phosphatidylinositols - biosynthesis; Phosphatidylinositols - genetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M608695200

Mycobacterium tuberculosis PimB has been demonstrated to catalyze the addition of a mannose residue from GDP-mannose to a monoacylated phosphatidyl- myo -inositol mannoside (Ac 1 PIM 1 ) to generate Ac 1 PIM 2 . 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 -C 16 /C 18:1 -(α- d -mannopyranosyl)-(1→4)-(α- d -glucopyranosyluronic acid)-(1→3)-glycerol (ManGlcAGroAc 2 ) and Gl-A as the precursor, GlcAGroAc 2 . In addition, C. glutamicum :: pimB was still able to produce Ac 1 PIM 2 , suggesting that Cg-PimB catalyzes the synthesis of ManGlcAGroAc 2 from GlcAGroAc 2 . 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-GroAc 2 in C. glutamicum :: pimB led to a severe reduction in LM. These results suggested that ManGlcAGroAc 2 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 ManGlcAGroAc 2 .