Mechanistic study of CMP-Neu5Ac hydrolysis by α2,3-sialyltransferase from Pasteurella dagmatis

Katharina Schmoelzer, Christiane Luley, Tibor Czabany, Doris Ribitsch, Helmut Schwab, Hansjörg Weber, Bernd Nidetzky*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Bacterial sialyltransferases of the glycosyltransferase family GT-80 exhibit pronounced hydrolase activity toward CMP-activated sialyl donor substrates. Using in situ proton NMR, we show that hydrolysis of CMP-Neu5Ac by Pasteurella dagmatis α2,3-sialyltransferase (PdST) occurs with axial-to-equatorial inversion of the configuration at the anomeric center to release the α-Neu5Ac product. We propose a catalytic reaction through a single displacement-like mechanism where water replaces the sugar substrate as a sialyl group acceptor. PdST variants having His284 in the active site replaced by Asn, Asp or Tyr showed up to 104-fold reduced activity, but catalyzed CMP-Neu5Ac hydrolysis with analogous inverting stereochemistry. The proposed catalytic role of His284 in the PdST hydrolase mechanism is to facilitate the departure of the CMP leaving group.
Original languageEnglish
Pages (from-to)2978-2984
JournalFEBS Letters
Issue number17
Publication statusPublished - 2014

Fields of Expertise

  • Human- & Biotechnology

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