Molecular Basis for Inhibition of Heparanases and β-Glucuronidases by Siastatin B

作者：Yurong Chen, Adrianus M. C. H. van den Nieuwendijk, Liang Wu, E. J. MORAN, Foteini Skoulikopoulou, Vera van Riet, Herman S. Overkleeft, G.J. Davies, Zachary Armstrong · 发表于：Journal of the American Chemical Society · 年份：2023 · DOI：10.1021/jacs.3c04162 · 被引用次数：8 · 研究领域：Carbohydrate Chemistry and Synthesis、Glycosylation and Glycoproteins Research、Proteoglycans and glycosaminoglycans research

High Resolution Image Download MS PowerPoint Slide Siastatin B is a potent and effective iminosugar inhibitor of three diverse glycosidase classes, namely, sialidases, β- d -glucuronidases, and N -acetyl-glucosaminidases. The mode of inhibition of glucuronidases, in contrast to sialidases, has long been enigmatic as siastatin B appears too bulky and incorrectly substituted to be accommodated within a β- d -glucuronidase active site pocket. Herein, we show through crystallographic analysis of protein-inhibitor complexes that siastatin B generates both a hemiaminal and a 3-geminal diol iminosugar (3-GDI) that are, rather than the parent compound, directly responsible for enzyme inhibition. The hemiaminal product is the first observation of a natural product that belongs to the noeuromycin class of inhibitors. Additionally, the 3-GDI represents a new and potent class of the iminosugar glycosidase inhibitor. To substantiate our findings, we synthesized both the gluco - and galacto -configured 3-GDIs and characterized their binding both structurally and kinetically to exo-β- d -glucuronidases and the anticancer target human heparanase. This revealed submicromolar inhibition of exo-β- d -glucuronidases and an unprecedented binding mode by this new class of inhibitor. Our results reveal the mechanism by which siastatin B acts as a broad-spectrum glycosidase inhibitor, identify a new class of glycosidase inhibitor, and suggest new functionalities that can be incorporated into future ...