Interaction of a Novel GDP Exchange Inhibitor with the Ras Protein

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• 作者：Ashit K. Ganguly ; Yu-Sen Wang ; Birendra N. Pramanik ; Ronald J. Doll ; Mark E. Snow ; Arthur G. Taveras ; Stacy Remiszewski ; David Cesarz ; J. del Rosario ; Bancha Vibulbhan ; Joan E. Brown ; Paul Kirschmeier
• 刊名：Biochemistry
• 出版年：1998
• 出版时间：November 10, 1998
• 年：1998
• 卷：37
• 期：45
• 页码：15631 - 15637
• 全文大小：99K
• 年卷期：v.37,no.45(November 10, 1998)
• ISSN：1520-4995

文摘

Mutated, tumorigenic Ras is present in a variety of human tumors. Compounds that inhibittumorigenic Ras function may be useful in the treatment of Ras-related tumors. The interaction of anovel GDP exchange inhibitor (SCH-54292) with the Ras-GDP protein was studied by NMR spectroscopy.The binding of the inhibitor to the Ras protein was enhanced at low Mg²⁺ concentrations, which enabledthe preparation of a stable complex for NMR study. To understand the enhanced inhibitor binding andthe increased GDP dissociation rates of the Ras protein, the conformational changes of the Ras protein atlow Mg²⁺ concentrations was investigated using two-dimensional ¹H-¹⁵N HSQC experiments. The Rasprotein existed in two conformations in slow exchange on the NMR time scale under such conditions.The conformational changes mainly occurred in the GDP binding pocket, in the switch I and the switchII regions, and were reversible. The Ras protein resumed its regular conformation after an excess amountof Mg²⁺ was added. A model of the inhibitor in complex with the Ras-GDP protein was derived fromintra- and intermolecular NOE distance constraints, and revealed that the inhibitor bound to the criticalswitch II region of the Ras protein.