1. Identification of an alpha(1-->6) mannopyranosyltransferase (MptA), involved in Corynebacterium glutamicum lipomanann biosynthesis, and identification of its orthologue in Mycobacterium tuberculosis.
- Author
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Mishra AK, Alderwick LJ, Rittmann D, Tatituri RV, Nigou J, Gilleron M, Eggeling L, and Besra GS
- Subjects
- Amino Acid Sequence, Bacterial Proteins chemistry, Cell Membrane enzymology, Corynebacterium glutamicum genetics, Corynebacterium glutamicum growth & development, Genome, Bacterial, Glycolipids biosynthesis, Glycolipids chemistry, Lipopolysaccharides chemistry, Lipopolysaccharides isolation & purification, Mannosyltransferases chemistry, Molecular Sequence Data, Mutation genetics, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Substrate Specificity, Bacterial Proteins metabolism, Corynebacterium glutamicum enzymology, Lipopolysaccharides biosynthesis, Mannosyltransferases metabolism, Mycobacterium tuberculosis enzymology, Sequence Homology, Amino Acid
- Abstract
Corynebacterium glutamicum and Mycobacterium tuberculosis share a similar cell wall architecture, and the availability of their genome sequences has enabled the utilization of C. glutamicum as a model for the identification and study of, otherwise essential, mycobacterial genes involved in lipomannan (LM) and lipoarabinomannan (LAM) biosynthesis. We selected the putative glycosyltransferase-Rv2174 from M. tuberculosis and deleted its orthologue NCgl2093 from C. glutamicum. This resulted in the formation of a novel truncated lipomannan (Cg-t-LM) and a complete ablation of LM/LAM biosynthesis. Purification and characterization of Cg-t-LM revealed an overall decrease in molecular mass, a reduction of alpha(1-->6) and alpha(1-->2) glycosidic linkages illustrating a reduced degree of branching compared with wild-type LM. The deletion mutant's biochemical phenotype was fully complemented by either NCgl2093 or Rv2174. Furthermore, the use of a synthetic neoglycolipid acceptor in an in vitro cell-free assay utilizing the sugar donor beta-D-mannopyranosyl-1-monophosphoryl-decaprenol together with the neoglycolipid acceptor alpha-D-Manp-(1-->6)-alpha-D-Manp-O-C8 as a substrate, confirmed NCgl2093 and Rv2174 as an alpha(1-->6) mannopyranosyltransferase (MptA), involved in the latter stages of the biosynthesis of the alpha(1-->6) mannan core of LM. Altogether, these studies have identified a new mannosyltransferase, MptA, and they shed further light on the biosynthesis of LM/LAM in Corynebacterianeae.
- Published
- 2007
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