9-O-Acetylation of sialic acids is catalysed by CASD1 via a covalent acetyl-enzyme intermediate

Nat Commun. 2015 Jul 14:6:7673. doi: 10.1038/ncomms8673.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Acetyltransferases / genetics*
  • Acetyltransferases / metabolism
  • Animals
  • CHO Cells
  • CRISPR-Cas Systems
  • Catalysis
  • Catalytic Domain
  • Cell Line
  • Cell Line, Tumor
  • Chromatography, High Pressure Liquid
  • Cricetulus
  • Dogs
  • Electrophoresis, Polyacrylamide Gel
  • Gene Knockout Techniques
  • HEK293 Cells
  • Humans
  • In Vitro Techniques
  • Madin Darby Canine Kidney Cells
  • Mass Spectrometry
  • Mice
  • Mutagenesis, Site-Directed
  • Organisms, Genetically Modified
  • Reverse Transcriptase Polymerase Chain Reaction
  • Saccharomyces cerevisiae
  • Sf9 Cells
  • Sialic Acids / metabolism*
  • Sialyltransferases / metabolism*
  • Spodoptera

Substances

  • Sialic Acids
  • 9-O-acetyl-N-acetylneuraminic acid
  • Acetyltransferases
  • CasD1 protein, human
  • Sialyltransferases
  • alpha-N-acetylneuraminate alpha-2,8-sialyltransferase