The interaction of mitochondrial translational initiation factor 2 with the small ribosomal subunit

Angela C. Spencer, Linda L. Spremulli

25 Scopus citations

Abstract

Bovine mitochondrial translational initiation factor 2 (IF-2mt) is organized into four domains, an N-terminal domain, a central G-domain and two C-terminal domains. These domains correspond to domains III-VI in the six-domain model of Escherichia coli IF-2. Variants in IF-2mt were prepared and tested for their abilities to bind the small (28S) subunit of the mitochondrial ribosome. The binding of wild-type IF-2mt was strong (Kd∼10-20 nM) and was not affected by fMet-tRNA. Deletion of the N-terminal domain substantially reduced the binding of IF-2mt to 28S subunits. However, the addition of fMet-tRNA stimulated the binding of this variant at least 2-fold demonstrating that contacts between fMet-tRNA and IF-2mt can stabilize the binding of this factor to 28S subunits. No binding was observed for IF-2mt variants lacking the G-domain which probably plays a critical role in organizing the structure of IF-2mt. IF-2mt contains a 37-amino acid insertion region between domains V and VI that is not found in the prokaryotic factors. Mutations in this region caused a significant reduction in the ability of the factor to promote initiation complex formation and to bind 28S subunits.

Original languageEnglish (US)
Pages (from-to)69-81
Number of pages13
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume1750
Issue number1
DOIs
Publication statusPublished - Jun 15 2005

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Keywords

  • Bovine
  • Initiation
  • Initiation factor 2
  • Mitochondria
  • Protein synthesis
  • Small ribosomal subunit
  • tRNA

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biophysics
  • Biochemistry
  • Molecular Biology

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