Structures of mammalian ER alpha-glucosidase II capture the binding modes of broad-spectrum iminosugar antivirals
Abstract
The biosynthesis of enveloped viruses depends heavily on the host cell endoplasmic reticulum (ER) glycoprotein quality control (QC) machinery. This dependency exceeds the dependency of host glycoproteins, offering a window for the targeting of ERQC for the development of broad-spectrum antivirals. We determined smallangle X-ray scattering (SAXS) and crystal structures of themain ERQC enzyme, ER alpha-glucosidase II (alpha-GluII; from mouse), alone and in complex with key ligands of its catalytic cycle and antiviral iminosugars, including two that are in clinical trials for the treatment of dengue fever. The SAXS data capture the enzyme's quaternary structure and suggest a conformational rearrangement is needed for the simultaneous binding of a monoglucosylated glycan to both subunits. The X-ray structures with key catalytic cycle intermediates highlight that an insertion between the + 1 and + 2 subsites contributes to the enzyme's activity and substrate specificity, and reveal that the presence of D-mannose at the + 1 subsite renders the acid catalyst less efficient during the cleavage of the monoglucosylated substrate. The complexes with iminosugar antivirals suggest that inhibitors targeting a conserved ring of aromatic residues between the alpha-GluII + 1 and + 2 subsites would have increased potency and selectivity, thus providing a template for further rational drug design.
Autore Pugliese
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Caputo A.T.; Alonzi D.S.; Marti L.; Reca I.-B.; Kiappes J. L.; Struwe W.B.; Cross A.; Basu S.; Lowe E.D.; Darlot B.; Santino A.; Roversi P.; Zitzmann N.
Titolo volume/Rivista
Proceedings of the National Academy of Sciences of the United States of America
Anno di pubblicazione
2016
ISSN
0027-8424
ISBN
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Numero di citazioni Wos
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Numero di citazioni Scopus
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Settori ERC
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Codici ASJC
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