Manno- epi-cyclophellitols Enable Activity-Based Protein Profiling of Human α-Mannosidases and Discovery of New Golgi Mannosidase II Inhibitors

Zachary Armstrong, Chi Lin Kuo, Daniël Lahav, Bing Liu, Rachel Johnson, Thomas J.M. Beenakker, Casper De Boer, Chung Sing Wong, Erwin R. Van Rijssel, Marjoke F. Debets, Bogdan I. Florea, Colin Hissink, Rolf G. Boot, Paul P. Geurink, Huib Ovaa, Mario Van Der Stelt, Gijsbert M. Van Der Marel, Jeroen D.C. Codée, Johannes M.F.G. Aerts, Liang WuHerman S. Overkleeft, Gideon J. Davies*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Golgi mannosidase II (GMII) catalyzes the sequential hydrolysis of two mannosyl residues from GlcNAcMan5GlcNAc2 to produce GlcNAcMan3GlcNAc2, the precursor for all complex N-glycans, including the branched N-glycans associated with cancer. Inhibitors of GMII are potential cancer therapeutics, but their usefulness is limited by off-target effects, which produce α-mannosidosis-like symptoms. Despite many structural and mechanistic studies of GMII, we still lack a potent and selective inhibitor of this enzyme. Here, we synthesized manno-epi-cyclophellitol epoxide and aziridines and demonstrate their covalent modification and time-dependent inhibition of GMII. Application of fluorescent manno-epi-cyclophellitol aziridine derivatives enabled activity-based protein profiling of α-mannosidases from both human cell lysate and mouse tissue extracts. Synthesized probes also facilitated a fluorescence polarization-based screen for dGMII inhibitors. We identified seven previously unknown inhibitors of GMII from a library of over 350 iminosugars and investigated their binding modalities through X-ray crystallography. Our results reveal previously unobserved inhibitor binding modes and promising scaffolds for the generation of selective GMII inhibitors.

Original languageEnglish
Pages (from-to)13021-13029
Number of pages9
JournalJournal of the American Chemical Society
Issue number30
Early online date1 Jul 2020
Publication statusPublished - 29 Jul 2020

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