Rosnizeck, Ina C. and Filchtinski, Daniel and Lopes, Rui Pedro and Kieninger, Baerbel and Herrmann, Christian and Kalbitzer, Hans Robert and Spoerner, Michael (2014) Elucidating the Mode of Action of a Typical Ras State 1(T) Inhibitor. BIOCHEMISTRY, 53 (24). pp. 3867-3878. ISSN 0006-2960,
Full text not available from this repository. (Request a copy)Abstract
The small GTPase Ras is an essential component of signal transduction pathways within the cell, controlling proliferation, differentiation, and apoptosis. Only in the GTP-bound form does Ras interact strongly with effector molecules such as Raf-kinase, thus acting as a molecular switch. In the GTP-bound form, Ras exists in a dynamic equilibrium between at least two distinct conformational states, 1(T) and 2(T), offering different functional properties of the protein. Zn2+-cyclen is a typical state 1(T) inhibitor; i.e., it interacts selectively with Ras in conformational state 1(T), a weak effector binding state. Here we report that active K-Ras4B, which is prominently found to be mutated in human tumors, exhibits a dynamic equilibrium like H-Ras, which can be modulated by Zn2+-cyclen. The titration experiments of Ras with Zn2+-cyclen indicate a cooperatively coupled binding of the ligands to the two interaction sites on Ras that could be identified for H-Ras previously. Our data further indicate that as in state 2(T) where induced fit produces the substate 2(T)* after effector binding, a corresponding substate 1(T)* can be detected at the state 1(T) mutant Ras(T35A). The interaction of Zn2+-cyclen with Ras not only shifts the equilibrium toward the weak effector binding state 1(T) but also perturbs the formation of substate 1(T)*, thus enhancing the inhibitory effect. Although Zn2+-cyclen shows an affinity for Ras in only the millimolar range, its potency of inhibition corresponds to a competitive state 2 inhibitor with micromolar binding affinity. Thus, the results demonstrate the mode of action and potency of this class of allosteric Ras inhibitors.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CONFORMATIONAL STATES; BINDING DOMAIN; K-RAS; EFFECTOR INTERACTION; NUCLEOTIDE EXCHANGE; DYNAMIC PROPERTIES; PROTEIN; GTP; CANCER; COMPLEXES; |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Dr. Hans Robert Kalbitzer |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 17 Oct 2019 13:24 |
| Last Modified: | 17 Oct 2019 13:24 |
| URI: | https://pred.uni-regensburg.de/id/eprint/10011 |
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