Download MendeleyNuclear magnetic resonance and molecular dynamics studies on the interactions of the Ras-binding domain of Raf-1 with wild-type and mutant Ras proteins.
Terada, T., Ito, Y., Shirouzu, M., Tateno, M., Hashimoto, K., Kigawa, T., Ebisuzaki, T., Takio, K., Shibata, T., Yokoyama, S., Smith, B.O., Laue, E.D., Cooper, J.A.(1999) J Mol Biol 286: 219-232
- PubMed: 9931261
- DOI: https://doi.org/10.1006/jmbi.1998.2472
- Primary Citation of Related Structures:
1RRB - PubMed Abstract:
The Ras protein and its homolog, Rap1A, have an identical "effector region" (residues 32-40) preceded by Asp30-Glu31 and Glu30-Lys31, respectively. In the complex of the "Ras-like" E30D/K31E mutant Rap1A with the Ras-binding domain (RBD), residues 51-131 of Raf-1, Glu31 in Rap1A forms a tight salt bridge with Lys84 in Raf-1. However, we have recently found that Raf-1 RBD binding of Ras is indeed reduced by the E31K mutation, but is not affected by the E31A mutation. Here, the "Rap1A-like" D30E/E31K mutant of Ras was prepared and shown to bind the Raf-1 RBD less strongly than wild-type Ras, but slightly more tightly than the E31K mutant. The backbone 1H, 13C, and 15N magnetic resonances of the Raf-1 RBD were assigned in complexes with the wild-type and D30E/E31K mutant Ras proteins in the guanosine 5'-O-(beta,gamma-imidotriphosphate)-bound form. The Lys84 residue in the Raf-1 RBD exhibited a large change in chemical shift upon binding wild-type Ras, suggesting that Lys84 interacts with wild-type Ras. The D30E/E31K mutant of Ras caused nearly the same perturbations in Raf-1 chemical shifts, including that of Lys84. We hypothesized that Glu31 in Ras may not be the major salt bridge partner of Lys84 in Raf-1. A molecular dynamics simulation of a model structure of the Raf-1 RBD.Ras.GTP complex suggested that Lys84 in Raf-1 might instead form a tight salt bridge with Asp33 in Ras. Consistent with this, the D33A mutation in Ras greatly reduced its Raf-I RBD binding activity. We conclude that the major salt bridge partner of Lys84 in Raf-1 may be Asp33 in Ras.
Organizational Affiliation:
Cellular Signaling Laboratory, The Institute of Physical and Chemical Research, 2-1 Hirosawa Wako-shi. Saitama 351-0198, Japan.
