An 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

Toshiyuki Shimizu, Kentaro Ihara, Ryoko Maesaki, Shinya Kuroda, Kozo Kaibuchi, Toshio Hakoshima

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Mg2+ 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 Mg2+ at 2.0-A resolution. Elimination of a Mg2+ 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 structruce reveals an important regulatory role for Mg2+ and suggests that guanine nucleotide exchange factor may utilize this feature of switch I to produce an open conformation in GDP/GTP exchange.

Original languageEnglish
Pages (from-to)18311-18317
Number of pages7
JournalJournal of Biological Chemistry
Volume275
Issue number24
DOIs
Publication statusPublished - 16-06-2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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