Current Genetics

, Volume 53, Issue 3, pp 185–192

Mitochondrial release factor in yeast: interplay of functional domains

  • Jan Kutner
  • Joanna Towpik
  • Krzysztof Ginalski
  • Magdalena Boguta
Research Article

DOI: 10.1007/s00294-008-0177-y

Cite this article as:
Kutner, J., Towpik, J., Ginalski, K. et al. Curr Genet (2008) 53: 185. doi:10.1007/s00294-008-0177-y

Abstract

The MRF1 gene encodes the only class I release factor found in Saccharomyces cerevisiae mitochondria, mRF1. The previously isolated point mutation mrf1-13 caused respiratory deficiency due to inhibition of mitochondrial translation. In this study, we have isolated second-site suppressors of mrf1-13. Among over 200 respiratory positive suppressor colonies, ten nuclear dominant suppressors had a new mutation in the MRF1 gene. The suppressors in combination with the original mrf1-13 revealed increased levels of mitochondrially synthesized proteins, Cox2 and Atp6. One of the suppressor alleles was cloned on a plasmid and was found to support weaker respiratory competence than in combination with mrf1-13. Finally, the possible effects of the suppressor mutations are discussed based on a structural model of mRF1 protein built for its “open” and “closed” forms using known crystal structures of prokaryotic release factor RF1 as templates. The 3D models suggest that at least some suppressors switch the structure of mRF1 from the “closed” to a permanently “open” form causing stronger binding of the mRF1 protein to the ribosome and increasing the time of ribosome occupation. This explains how the suppressor mutants may facilitate translation termination despite a defect in decoding of the stop signal.

Keywords

YeastMitochondriaTranslation terminationRelease factorSuppressor mutants

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Jan Kutner
    • 1
  • Joanna Towpik
    • 1
  • Krzysztof Ginalski
    • 2
  • Magdalena Boguta
    • 1
  1. 1.Department of Genetics, Institute of Biochemistry and BiophysicsPolish Academy of SciencesWarsawPoland
  2. 2.Interdisciplinary Centre for Mathematical and Computational ModellingUniversity of WarsawWarsawPoland