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Microbiology. 2012 Jul;158(Pt 7):1908-17. doi: 10.1099/mic.0.057653-0. Epub 2012 Apr 26.

Deletion of manC in Corynebacterium glutamicum results in a phospho-myo-inositol mannoside- and lipoglycan-deficient mutant.

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  • 1School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. a.k.mishra@bham.ac.uk

Abstract

Mannose is an important constituent of the immunomodulatory glycoconjugates of the mycobacterial cell wall: lipoarabinomannan (LAM), lipomannan (LM) and the related phospho-myo-inositol mannosides (PIMs). In Mycobacterium tuberculosis and the related bacillus Corynebacterium glutamicum, mannose is either imported from the medium or derived from glycolysis, and is subsequently converted into the nucleotide-based sugar donor guanosine diphosphomannose (GDP-mannose). This can be utilized by the glycosyltranferases of the GT-A/B superfamily or converted to the lipid-based donor polyprenyl monophosphomannose, and used as a substrate by the transmembrane glycosyltransferases of the GT-C superfamily. To investigate GDP-mannose biosynthesis in detail, the gene encoding a putative ManC in C. glutamicum was deleted. Deletion of manC resulted in a slow-growing mutant, with reduced but not totally abrogated guanosine diphosphomannose pyrophosphorylase activity. However, a comprehensive cell wall analysis revealed that C. glutamicumĪ”manC is deficient in PIMs and LM/LAM. Closer inspection suggests that promiscuous ManC activity is contributed by additional putative nucleotidyltransferases, PmmB, WbbL1, GalU and GlmU, and a hypothetical protein, NCgl0715. Furthermore, complementation analyses of C. glutamicumĪ”manC with Rv3264c suggested that it is a true homologue of ManC in M. tuberculosis, and the essentiality of PIMs in M. tuberculosis makes it an attractive drug target.

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