Artz Jennifer D, Dunford James E, Arrowood Michael J, Dong Aiping, Chruszcz Maksymilian, Kavanagh Kathryn L, Minor Wladek, Russell R Graham G, Ebetino F Hal, Oppermann Udo, Hui Raymond
Structural Genomics Consortium, University of Toronto, 101 College Street, Toronto, ON M5G 1L7, Canada.
Chem Biol. 2008 Dec 22;15(12):1296-306. doi: 10.1016/j.chembiol.2008.10.017.
Cryptosporidiosis is a neglected disease without a wholly effective drug. We present a study demonstrating nitrogen-containing bisphosphonates (N-BPs) to be capable of inhibiting Cryptosporidium parvum at low micromolar concentrations in infected MDCK cells. Predictably, the mechanism of action is based on inhibition of biosynthesis of isoprenoids but the target enzyme is unexpectedly a distinctive C. parvum enzyme dubbed nonspecific polyprenyl pyrophosphate synthase (CpNPPPS). This enzyme produces various isoprenoid products larger than FPP and is inhibited by N-BPs at subnanomolar concentrations. It is part of an isoprenoid pathway in Cryptosporidium distinctly different from other organisms. The proposed mechanism of action is corroborated by crystal structures of the enzyme with risedronate and zoledronate bound showing how this enzyme's unique chain length determinant region enables it to accommodate larger substrates and products. These results, combined with existing data on their clinical use, demonstrate that N-BPs are very promising anticryptosporidial drug candidates.
隐孢子虫病是一种被忽视的疾病，目前尚无完全有效的药物。我们开展了一项研究，结果表明含氮双膦酸盐（N-BPs）在低微摩尔浓度下就能抑制感染的MDCK细胞中的微小隐孢子虫。不出所料，其作用机制基于对类异戊二烯生物合成的抑制，但出人意料的是，靶酶是一种独特的微小隐孢子虫酶，称为非特异性聚异戊二烯焦磷酸合酶（CpNPPPS）。这种酶产生各种比法呢基焦磷酸（FPP）更大的类异戊二烯产物，并在亚纳摩尔浓度下被N-BPs抑制。它是隐孢子虫类异戊二烯途径的一部分，与其他生物明显不同。结合了利塞膦酸盐和唑来膦酸盐的该酶晶体结构证实了所提出的作用机制，展示了该酶独特的链长决定区如何使其能够容纳更大的底物和产物。这些结果，再结合它们临床应用的现有数据，表明N-BPs是非常有前景的抗隐孢子虫病候选药物。
