Mechanism of Inhibition of Human KSP by Monastrol: Insights from Kinetic Analysis and the Effect of Ionic Strength on KSP Inhibition

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• 作者：Lusong Luo ; Jeffrey D. Carson ; Dashyant Dhanak ; Jeffrey R. Jackson ; Pearl S. Huang ; Yan Lee ; Roman Sakowicz ; and Robert A. Copeland
• 刊名：Biochemistry
• 出版年：2004
• 出版时间：December 7, 2004
• 年：2004
• 卷：43
• 期：48
• 页码：15258 - 15266
• 全文大小：155K
• 年卷期：v.43,no.48(December 7, 2004)
• ISSN：1520-4995

文摘

Kinesin motor proteins utilize the energy from ATP hydrolysis to transport cellular cargoalong microtubules. Kinesins that play essential roles in the mechanics of mitosis are attractive targets fornovel antimitotic cancer therapies. Monastrol, a cell-permeable inhibitor that specifically inhibits the kinesinEg5, the Xenopus laevis homologue of human KSP, can cause mitotic arrest and monopolar spindleformation. In this study, we show that the extent of monastrol inhibition of KSP microtubule-stimulatedATP hydrolysis is highly dependent upon ionic strength. Detailed kinetic analysis of KSP inhibition bymonastrol in the presence and absence of microtubules suggests that monastrol binds to the KSP-ADPcomplex, forming a KSP-ADP-monastrol ternary complex, which cannot bind to microtubulesproductively and cannot undergo further ATP-driven conformational changes.