title: GlcNAc 2-epimerase can serve a catabolic role in sialic acid metabolism.
abstract: Sialic acid is a major determinant of carbohydrate-receptor interactions in many systems pertinent to human health and disease. N-Acetylmannosamine (ManNAc) is the first committed intermediate in the sialic acid biosynthetic pathway; thus, the mechanisms that control intracellular ManNAc levels are important regulators of sialic acid production. UDP-GlcNAc 2-epimerase and GlcNAc 2-epimerase are two enzymes capable of generating ManNAc from UDP-GlcNAc and GlcNAc, respectively. Whereas the former enzyme has been shown to direct metabolic flux toward sialic acid in vivo, the function of the latter enzyme is unclear. Here we study the effects of GlcNAc 2-epimerase expression on sialic acid production in cells. A key tool we developed for this study is a cell-permeable, small molecule inhibitor of GlcNAc 2-epimerase designed based on mechanistic principles. Our results indicate that, unlike UDP-GlcNAc 2-epimerase, which promotes biosynthesis of sialic acid, GlcNAc 2-epimerase can serve a catabolic role, diverting metabolic flux away from the sialic acid pathway.
authors.affiliation: Department of Chemistry, University of California, Berkeley 94720, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Luchansky
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Yarema
authors.forename: Saori
authors.initials: S
authors.lastname: Takahashi
authors.forename: Carolyn R
authors.initials: CR
authors.lastname: Bertozzi
mesh_terms: D001483:Base Sequence; D002238:Carbohydrate Epimerases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D012333:RNA, Messenger / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D002238:Carbohydrate Epimerases; C024519:N-acyl-D-glucosamine 2-epimerase; C498259:RENBP protein, human; D019158:N-Acetylneuraminic Acid