title: Arabinan-deficient mutants of Corynebacterium glutamicum and the consequent flux in decaprenylmonophosphoryl-D-arabinose metabolism.
abstract: The arabinogalactan (AG) of Corynebacterianeae is a critical macromolecule that tethers mycolic acids to peptidoglycan, thus forming a highly impermeable cell wall matrix termed the mycolyl-arabinogalactan peptidoglycan complex (mAGP). The front line anti-tuberculosis drug, ethambutol (Emb), targets the Mycobacterium tuberculosis and Corynebacterium glutamicum arabinofuranosyltransferase Mt-EmbA, Mt-EmbB and Cg-Emb enzymes, respectively, which are responsible for the biosynthesis of the arabinan domain of AG. The substrate utilized by these important glycosyltransferases, decaprenylmonophosphoryl-D-arabinose (DPA), is synthesized via a decaprenylphosphoryl-5-phosphoribose (DPPR) synthase (UbiA), which catalyzes the transfer of 5-phospho-ribofuranose-pyrophosphate (pRpp) to decaprenol phosphate to form DPPR. Glycosyl compositional analysis of cell walls extracted from a C. glutamicum::ubiA mutant revealed a galactan core consisting of alternating beta(1-->5)-Galf and beta(1-->6)-Galf residues, completely devoid of arabinan and a concomitant loss of cell-wall-bound mycolic acids. In addition, in vitro assays demonstrated a complete loss of arabinofuranosyltransferase activity and DPA biosynthesis in the C. glutamicum::ubiA mutant when supplemented with p[14C]Rpp, the precursor of DPA. Interestingly, in vitro arabinofuranosyltransferase activity was restored in the C. glutamicum::ubiA mutant when supplemented with exogenous DP[14C]A substrate, and C. glutamicum strains deficient in ubiA, emb, and aftA all exhibited different levels of DPA biosynthesis.
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Alderwick
authors.forename: Lynn G
authors.initials: LG
authors.lastname: Dover
authors.forename: Mathias
authors.initials: M
authors.lastname: Seidel
authors.forename: Roland
authors.initials: R
authors.lastname: Gande
authors.forename: Hermann
authors.initials: H
authors.lastname: Sahm
authors.forename: Lothar
authors.initials: L
authors.lastname: Eggeling
authors.forename: Gurdyal S
authors.initials: GS
authors.lastname: Besra
mesh_terms: D000595:Amino Acid Sequence; D001089:Arabinose / Q000031:analogs & derivatives* / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000201:enzymology / Q000378:metabolism*; D005685:Galactans / Q000096:biosynthesis / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010457:Peptidoglycan / Q000378:metabolism; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000096:biosynthesis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013729:Terpenes / Q000378:metabolism*
chemical_list: D005685:Galactans; D010457:Peptidoglycan; D011134:Polysaccharides; D013729:Terpenes; C053856:arabinogalactan-peptidoglycan complex; C089328:decaprenyl-P-arabinose; C030080:araban; D001089:Arabinose; D017856:Phosphotransferases (Phosphate Group Acceptor); C517974:decaprenylphosphoryl-5-phosphoribose synthase; C005653:arabinogalactan