Decaprenylphosphoryl Arabinofuranose, the Donor of the d -Arabinofuranosyl Residues of Mycobacterial Arabinan, Is Formed via a Two-Step Epimerization of Decaprenylphosphoryl Ribose

• DOI: 10.1128/jb.187.23.8020-8025.2005
• Publication Date: 2005-11-16T02:48:42Z
• Authors: Katarína Mikušová; Hairong Huang; Tetsuya Yagi; Marcelle Holsters; Danny Vereecke; Wim D'Haeze; Michael S. Scherman; Patrick J. Brennan; Michael R. McNeil; Dean C. Crick
• Keywords: Epimer; Arabinogalactan; Ribose; Residue (chemistry)

The major cell wall polysaccharide of mycobacteria is a branched-chain arabinogalactan in which arabinan chains are attached to the 5 carbon some 6-linked galactofuranose residues; these composed exclusively D-arabinofuranose (Araf) residues. immediate precursor polymerized Araf decaprenylphosphoryl-D-Araf, derived from 5-phosphoribose 1-diphosphate (pRpp) an undefined manner. On basis time course, feedback, and chemical reduction experiment results we propose that decaprenylphosphoryl-Araf synthesized by following sequence events. (i) pRpp transferred decaprenyl-phosphate molecule form decaprenylphosphoryl-beta-D-5-phosphoribose. (ii) Decaprenylphosphoryl-beta-D-5-phosphoribose dephosphorylated decaprenylphosphoryl-beta-D-ribose. (iii) hydroxyl group at 2 position ribose oxidized likely decaprenylphosphoryl-2-keto-beta-D-erythro-pentofuranose. (iv) Decaprenylphosphoryl-2-keto-beta-D-erythro-pentofuranose reduced decaprenylphosphoryl-beta-D-Araf. Thus, epimerization ribosyl arabinosyl residue occurs lipid-linked level; this first report epimerase utilizes sugar as substrate. similarity proteins implicated arabinosylation Azorhizobium caulidans nodulation factor, two genes were cloned Mycobacterium tuberculosis genome expressed heterologous host, protein was purified. Together, (Rv3790 Rv3791) able catalyze epimerization, although neither individually sufficient support activity.