title: Discovery of inhibitors of Leishmania β-1,2-mannosyltransferases using a click-chemistry-derived guanosine monophosphate library.
abstract: Leishmania spp. are a medically important group of protozoan parasites that synthesize a novel intracellular carbohydrate reserve polymer termed mannogen. Mannogen is a soluble homopolymer of β-1,2-linked mannose residues that accumulates in the major pathogenic stages in the sandfly vector and mammalian host. While several steps in mannogen biosynthesis have been defined, none of the enzymes have been isolated or characterized. We report the development of a simple assay for the GDP-mannose-dependent β-1,2-mannosyltransferases involved in mannogen synthesis. This assay utilizes octyl α-D-mannopyranoside to prime the formation of short mannogen oligomers up to 5 mannose residues. This assay was used to screen a focussed library of 44 GMP-triazole adducts for inhibitors. Several compounds provided effective inhibition of mannogen β-1,2-mannosyltransferases in a cell-free membrane preparation. This assay and inhibitor compounds will be useful for dissecting the role of different mannosyltransferases in regulating de novo biosynthesis and elongation reactions in mannogen metabolism.
authors.affiliation: School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Phillip
authors.initials: P
authors.lastname: van der Peet
authors.forename: Julie E
authors.initials: JE
authors.lastname: Ralton
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: McConville
authors.forename: Spencer J
authors.initials: SJ
authors.lastname: Williams
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000494:pharmacology*; D001386:Azides / Q000737:chemistry; D002474:Cell-Free System; D002626:Chemistry, Pharmaceutical / Q000379:methods; D020650:Combinatorial Chemistry Techniques; D005260:Female; D015723:Gene Library; D006153:Guanosine Diphosphate / Q000737:chemistry; D006155:Guanosine Diphosphate Mannose / Q000737:chemistry; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D007891:Leishmania / Q000201:enzymology*; D008024:Ligands; D008364:Mannosyltransferases / Q000737:chemistry*; D008956:Models, Chemical; D011108:Polymers / Q000737:chemistry; D011576:Psychodidae; D014230:Triazoles / Q000737:chemistry
chemical_list: D000977:Antiparasitic Agents; D001386:Azides; D008024:Ligands; D011108:Polymers; D014230:Triazoles; D006153:Guanosine Diphosphate; D006155:Guanosine Diphosphate Mannose; D008364:Mannosyltransferases; C106904:beta-1,2-mannosyltransferase IV