2Strasbourg University, UMR No. 7156 GMGM, 21 rue Rene Descartes, 67084 Strasbourg, France; E-mail: firstname.lastname@example.org
3Present address: Strasbourg University, Institute of Plant Molecular Biology, 4 rue General Zimmer, 67084 Strasbourg, France; E-mail: email@example.com
* To whom correspondence should be addressed.
Received April 27, 2016; Revision received May 23, 2016
Mitochondrial genomes of many eukaryotic organisms do not code for the full tRNA set necessary for organellar translation. Missing tRNA species are imported from the cytosol. In particular, one out of two cytosolic lysine tRNAs of the yeast Saccharomyces cerevisiae is partially internalized by mitochondria. The key protein factor of this process is the precursor of mitochondrial lysyl-tRNA synthetase, preMsk1p. In this work, we show that recombinant preMsk1p purified from E. coli in native conditions, when used in an in vitro tRNA import system, demonstrates some properties different from those shown by the renatured protein purified from E. coli in the denatured state. We also discuss the possible mechanistic reasons for this phenomenon.
KEY WORDS: mitochondria, tRNA, tRNA import into mitochondria, preMsk1p, Eno2p, import mechanisms, protein conformation