title: 9-O-Acetylation of sialic acids is catalysed by CASD1 via a covalent acetyl-enzyme intermediate.
abstract: Sialic acids, terminal sugars of glycoproteins and glycolipids, play important roles in development, cellular recognition processes and host-pathogen interactions. A common modification of sialic acids is 9-O-acetylation, which has been implicated in sialoglycan recognition, ganglioside biology, and the survival and drug resistance of acute lymphoblastic leukaemia cells. Despite many functional implications, the molecular basis of 9-O-acetylation has remained elusive thus far. Following cellular approaches, including selective gene knockout by CRISPR/Cas genome editing, we here show that CASD1--a previously identified human candidate gene--is essential for sialic acid 9-O-acetylation. In vitro assays with the purified N-terminal luminal domain of CASD1 demonstrate transfer of acetyl groups from acetyl-coenzyme A to CMP-activated sialic acid and formation of a covalent acetyl-enzyme intermediate. Our study provides direct evidence that CASD1 is a sialate O-acetyltransferase and serves as key enzyme in the biosynthesis of 9-O-acetylated sialoglycans.
authors.affiliation: Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany.
authors.forename: Anna-Maria T
authors.initials: AM
authors.lastname: Baumann
authors.affiliation: Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands.
authors.forename: Mark J G
authors.initials: MJ
authors.lastname: Bakkers
authors.affiliation: Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany.
authors.forename: Falk F R
authors.initials: FF
authors.lastname: Buettner
authors.affiliation: Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany.
authors.forename: Maike
authors.initials: M
authors.lastname: Hartmann
authors.affiliation: Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Grove
authors.affiliation: Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands.
authors.forename: Martijn A
authors.initials: MA
authors.lastname: Langereis
authors.affiliation: Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands.
authors.forename: Raoul J
authors.initials: RJ
authors.lastname: de Groot
authors.affiliation: Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Mühlenhoff
mesh_terms: D000107:Acetylation; D000123:Acetyltransferases / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D064113:CRISPR-Cas Systems; D002384:Catalysis; D020134:Catalytic Domain; D002460:Cell Line; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D003412:Cricetulus; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D055786:Gene Knockout Techniques; D057809:HEK293 Cells; D006801:Humans; D066298:In Vitro Techniques; D061985:Madin Darby Canine Kidney Cells; D013058:Mass Spectrometry; D051379:Mice; D016297:Mutagenesis, Site-Directed; D030781:Organisms, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae; D061987:Sf9 Cells; D012794:Sialic Acids / Q000378:metabolism*; D012799:Sialyltransferases / Q000378:metabolism*; D018411:Spodoptera
chemical_list: D000123:Acetyltransferases; D012794:Sialic Acids; D012799:Sialyltransferases; C025676:9-O-acetyl-N-acetylneuraminic acid; C561597:CASD1 protein, human; C043662:alpha-N-acetylneuraminate alpha-2,8-sialyltransferase