title: CMP-Sialic Acid Synthetase: The Point of Constriction in the Sialylation Pathway.
abstract: Sialoglycoconjugates form the outermost layer of animal cells and play a crucial role in cellular communication processes. An essential step in the biosynthesis of sialylated glycoconjugates is the activation of sialic acid to the monophosphate diester CMP-sialic acid. Only the activated sugar is transported into the Golgi apparatus and serves as a substrate for the linkage-specific sialyltransferases. Interference with sugar activation abolishes sialylation and is embryonic lethal in mammals. In this chapter we focus on the enzyme catalyzing the activation of sialic acid, the CMP-sialic acid synthetase (CMAS), and compare the enzymatic properties of CMASs isolated from different species. Information concerning the reaction mechanism and active site architecture is included. Moreover, the unusual nuclear localization of vertebrate CMASs as well as the biotechnological application of bacterial CMAS enzymes is addressed.
authors.affiliation: Institute for Cellular Chemistry, Hannover Medical School (MHH), Hannover, 30625, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Sellmeier
authors.forename: Birgit
authors.initials: B
authors.lastname: Weinhold
authors.forename: Anja
authors.initials: A
authors.lastname: Münster-Kühnel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000737:chemistry / Q000201:enzymology*; D001692:Biological Transport; D020134:Catalytic Domain; D002450:Cell Communication; D003569:Cytidine Monophosphate N-Acetylneuraminic Acid / Q000737:chemistry / Q000378:metabolism*; D005057:Eukaryotic Cells / Q000737:chemistry / Q000201:enzymology*; D006001:Glycoconjugates / Q000737:chemistry / Q000378:metabolism*; D006056:Golgi Apparatus / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000216:N-Acylneuraminate Cytidylyltransferase / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D006001:Glycoconjugates; D003569:Cytidine Monophosphate N-Acetylneuraminic Acid; D000216:N-Acylneuraminate Cytidylyltransferase