Download MendeleyAn open conformation of switch I revealed by the crystal structure of a Mg2+-free form of RHOA complexed with GDP. Implications for the GDP/GTP exchange mechanism.
Shimizu, T., Ihara, K., Maesaki, R., Kuroda, S., Kaibuchi, K., Hakoshima, T.(2000) J Biol Chem 275: 18311-18317
- PubMed: 10748207
- DOI: https://doi.org/10.1074/jbc.M910274199
- Primary Citation of Related Structures:
1DPF - PubMed Abstract:
Mg(2+) ions are essential for guanosine triphosphatase (GTPase) activity and play key roles in guanine nucleotide binding and preserving the structural integrity of GTP-binding proteins. We determined the crystal structure of a small GTPase RHOA complexed with GDP in the absence of Mg(2+) at 2.0-A resolution. Elimination of a Mg(2+) ion induces significant conformational changes in the switch I region that opens up the nucleotide-binding site. Similar structural changes have been observed in the switch regions of Ha-Ras bound to its guanine nucleotide exchange factor, Sos. This RHOA-GDP structure reveals an important regulatory role for Mg(2+) and suggests that guanine nucleotide exchange factor may utilize this feature of switch I to produce an open conformation in GDP/GTP exchange.
Organizational Affiliation:
Division of Strucural Biology and Signal Transduction, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
