Download MendeleyHow RhoGDI binds Rho.
Longenecker, K., Read, P., Derewenda, U., Dauter, Z., Liu, X., Garrard, S., Walker, L., Somlyo, A.V., Nakamoto, R.K., Somlyo, A.P., Derewenda, Z.S.(1999) Acta Crystallogr D Biol Crystallogr 55: 1503-1515
- PubMed: 10489445
- DOI: https://doi.org/10.1107/s090744499900801x
- Primary Citation of Related Structures:
1CC0 - PubMed Abstract:
Like all Rho (Ras homology) GTPases, RhoA functions as a molecular switch in cell signaling, alternating between GTP- and GDP-bound states, with its biologically inactive GDP-bound form maintained as a cytosolic complex with RhoGDI (guanine nucleotide-exchange inhibitor). The crystal structures of RhoA-GDP and of the C-terminal immunoglobulin-like domain of RhoGDI (residues 67-203) are known, but the mechanism by which the two proteins interact is not known. The functional human RhoA-RhoGDI complex has been expressed in yeast and crystallized (P6(5)22, unit-cell parameters a = b = 139, c = 253 A, two complexes in the asymmetric unit). Although diffraction from these crystals extends to 3.5 A and is highly anisotropic, the experimentally phased (MAD plus MIR) electron-density map was adequate to reveal the mutual disposition of the two molecules. The result was validated by molecular-replacement calculations when data were corrected for anisotropy. Furthermore, the N-terminus of RhoGDI (the region involved in inhibition of nucleotide exchange) can be identified in the electron-density map: it is bound to the switch I and switch II regions of RhoA, occluding an epitope which binds Dbl-like nucleotide-exchange factors. The entrance of the hydrophobic pocket of RhoGDI is 25 A from the last residue in the RhoA model, with its C-terminus oriented to accommodate the geranylgeranyl group without conformational change in RhoA.
Organizational Affiliation:
Department of Molecular Physiology and Biological Physics, University of Virginia Health Sciences Center, Charlottesville, VA 22906, USA.
