Characterizing the selectivity of ER ?-glucosidase inhibitors.

ABSTRACT: The endoplasmic reticulum (ER) contains both ?-glucosidases and ?-mannosidases which process the N-linked oligosaccharides of newly synthesized glycoproteins and thereby facilitate polypeptide folding and glycoprotein quality control. By acting as structural mimetics, iminosugars can selectively inhibit these ER localized ?-glycosidases, preventing N-glycan trimming and providing a molecular basis for their therapeutic applications. In this study, we investigate the effects of a panel of nine iminosugars on the actions of ER luminal ?-glucosidase I and ?-glucosidase II. Using ER microsomes to recapitulate authentic protein N-glycosylation and oligosaccharide processing, we identify five iminosugars that selectively inhibit N-glycan trimming. Comparison of their inhibitory activities in ER microsomes against their effects on purified ER ?-glucosidase II, suggests that 3,7a-diepi-alexine acts as a selective inhibitor of ER ?-glucosidase I. The other active iminosugars all inhibit ?-glucosidase II and, having identified 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) as the most effective of these compounds, we use in silico modeling to understand the molecular basis for this enhanced activity. Taken together, our work identifies the C-3 substituted pyrrolizidines casuarine and 3,7a-diepi-alexine as promising "second-generation" iminosugar inhibitors.

SUBMITTER: O'Keefe S 

PROVIDER: S-EPMC6583763 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature