Functional changes in the structure of the SRP GTPase on binding GDP and Mg2+GDP

Douglas M. Freymann*, Robert J. Keenan, Robert M. Stroud, Peter Walter

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


Ffh is a component of a bacterial ribonucleoprotein complex homologous to the signal recognition particle (SRP) of eukaryotes. It comprises three domains that mediate both binding to the hydrophobic signal sequence of the nascent polypeptide and the GTP-dependent interaction of Ffh with a structurally homologous GTPase of the SRP receptor. The X-ray structures of the two-domain 'NG' GTPase of Ffh in complex with Mg2+GDP and GDP have been determined at 2.0 Å resolution. The structures explain the low nucleotide affinity of Ffh and locate two regions of structural mobility at opposite sides of the nucleotide-binding site. One of these regions includes highly conserved sequence motifs that presumably contribute to the structural trigger signaling the GTP-bound state. The other includes the highly conserved interface between the N and G domains, and supports the hypothesis that the N domain regulates or signals the nucleotide occupancy of the G domain.

Original languageEnglish (US)
Pages (from-to)793-801
Number of pages9
JournalNature Structural Biology
Issue number8
StatePublished - 1999

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Genetics

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