ИСТИНА

The main objective of the present work was to decrypt the mechanisms of transfer RNA targeting into yeast and human mitochondria. This work focused mainly on the initial targeting step of tRK1 import into mitochondria both in human cells and yeast as well as on the role of glycolytic enzyme Eno2p in this process. Functional studies of the mitochondrial import in yeast have suggested that a second isoform of the glycolytic enzyme enolase is an essential part of the tRK1 mitochondrial targeting process (Entelis et al., 2006). Together with another protein factor, preMSK1p, this enzyme represents a minimum system sufficient to provide the mitochondrial import of tRK1 in vitro. There are data indicating the interaction between Eno2p and tRK1 as well as a chaperone activity of Eno2p in the complex with tRK1 (Entelis et al., 2006; Kolesnikova et al., 2010). Nevertheless, the nature of this interaction is still unkown. We also hypothesized that human cells use a similar mechanism for induced tRK1 import implicating human enolase as well. This hypothesis was based on previous studies indicating the engagement of orthologous proteins for the tRNA mitochondrial import in human cells. In order to reach the stated objective, we: Study whether human enolases are involved in tRK1 import into human mitochondria in vitro and in vivo; Study differences of conformational features of tRK1 and tRK2 in solution; Study the process of targeting of tRK1 into yeast mitochondria; Study the structures of tRK1-protein complexes involved in tRK1 import into yeast mitochondria.