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Decaprenyl-phospho-arabinose (b-d-arabinofuranosyl-1-O-monophospho-decaprenol), the only known donor of d-arabinose in bacteria, and its precursor, decaprenyl-phospho-ribose (b-d-ribofuranosyl-1-O-monophospho-decaprenol), were first described in 1992. | IFEBS Journal REVIEW ARTICLE Biosynthesis of D-arabinose in mycobacteria - a novel bacterial pathway with implications for antimycobacterial therapy Beata A. Wolucka Laboratory of MycobacterialBiochemistry Institute of Public Health Brussels Belgium Keywords cellwallbiosynthesis D-ribose ethambutol Mycobacterium tuberculosis mycolic acid polyisoprenoid glycolipid review Correspondence B. A. Wolucka Laboratory of Mycobacterial Biochemistry Institute of Public Health 642 Engeland Street B-1180 Brussels Belgium Fax 32 2 373 3282 Tel 32 2 373 3100 E-mail bwolucka@pasteur.be Received 8 February 2008 revised 6 March 2008 accepted 12 March 2008 doi 10.1111 j.1742-4658.2008.06395.x Decaprenyl-phospho-arabinose b-D-arabinofuranosyl-1-O-monophospho-decaprenol the only known donor of D-arabinose in bacteria and its precursor decaprenyl-phospho-ribose P-D-ribofuranosyl-1-ơ-monophospho-decaprenol were first described in 1992. En route to D-arabinofuranose the decaprenyl-phospho-ribose 2 -epimerase converts decaprenyl-phospho-ribose to decaprenyl-phospho-arabinose which is a substrate for arabinosyltransfe-rases in the synthesis of the cell-wall arabinogalactan and lipoarabinomannan polysaccharides of mycobacteria. The first step of the proposed decaprenylphospho-arabinose biosynthesis pathway in Mycobacterium tuberculosis and related actinobacteria is the formation of D-ribose 5-phosphate from sedoheptulose 7-phosphate catalysed by the Rv1449 transketolase and or the isomerization of D-ribulose 5-phosphate catalysed by the Rv2465 D-ribose 5-phosphate isomerase. D-Ribose 5-phosphate is a substrate for the Rv1017 phosphoribosyl pyrophosphate synthetase which forms 5-phosphoribosyl 1-pyrophosphate PRPP . The activated 5-phosphoribofuranosyl residue of PRPP is transferred by the Rv3806 5-phosphoribosyltransferase to decaprenyl phosphate thus forming 5 -phosphoribosyl-monophospho-decaprenol. The dephosphorylation of 5 -phosphoribosyl-monophospho-decaprenol to .