Conformational change of the N-domain on formation of the complex between the GTPase domains of Thermus aquaticus Ffh and FtsY

Irina V. Shepotinovskaya, Douglas M. Freymann*

*Corresponding author for this work

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

The structural basis for the GTP-dependent co-translational targeting complex between the signal recognition particle (SRP) and its receptor is unknown. The complex has been shown to have unusual kinetics of formation, and association in vivo is likely to be dependent on catalysis by the SRP RNA. We have determined conditions for RNA-independent association of the 'NG' GTPase domains of the prokaryotic homologs of the SRP components, Ffh and FtsY, from Thermus aquaticus. Consistent with previous studies of the Escherichia coli proteins, the kinetics of association and dissociation are slow. The T. aquaticus FtsY is sensitive to an endogenous proteolytic activity that cleaves at two sites - the first in a lengthy linker peptide that spans the interface between the N and G domains, and the second near the N-terminus of the N domain of FtsY. Remarkably, this second cleavage occurs only on formation of the Ffh/FtsY complex. The change in protease sensitivity of this region, which is relatively unstructured in the FtsY but not in the Ffh NG domain, implies that it undergoes conformational change on formation of the complex between the two proteins. The N domain, therefore, participates in the interactions that mediate the GTP-dependent formation of the targeting complex.

Original languageEnglish (US)
Pages (from-to)107-114
Number of pages8
JournalBiochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
Volume1597
Issue number1
DOIs
StatePublished - May 20 2002

Keywords

  • Ffh
  • FtsY
  • GTPase
  • SRP

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology

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