Unite Mixte de Recherche 7156 GMGM, Department of Molecular and Cellular Genetics, Centre National de la Recherche Scientifique-ULP, 21 Rue Rene Descartes, Strasbourg 67084, France-
Abstract: In Saccharomyces cerevisiae, one of two cytosolic lysine-tRNAs is partially imported into mitochondria- We demonstrate that three components of the ubiquitin-26S proteasome system -UPS-, Rpn13p, Rpn8p and Doa1p interact with the imported tRNA and with the essential factor of its mitochondrial targeting, pre-Msk1p- Genetic and biochemical assays demonstrate that UPS plays a dual regulatory role, since the overall inhibition of cellular proteasome activity reduces tRNA import, while specific depletion of Rpn13p or Doa1p increases it- This result suggests a functional link between UPS and tRNA mitochondrial import in yeast and indicates on the existence of negative and positive import regulators-