| Popis: |
Mitochondrial translation depends on the macromolecular components imported from the cytosol, which include translation factors, ribosomal proteins, aminoacyl-tRNA synthetases, and a variable number of small noncoding RNAs. The lasts are essentially tRNAs, but other small RNAs, like mammalian 5S rRNA, are also concerned by the RNA mitochondrial targeting pathway. If their importance in mitochondrial translation was demonstrated in each case where it was addressed, the precise function of these molecules differs from one system to another: in many cases they complement lacking mtDNA encoded counterparts, in others can fulfill conditional functions, finally they can complement the lack of needed mitochondrial enzymatic activities. In any case, it appears that the innated capacity of mitochondria to import small RNA molecules is supplied by specific additional protein, often performing their “second job” to deliver the needed RNA in the organelle. This mechanism, still not understood in details, remains the unique natural pathway of nucleic acids delivery in mitochondria, and is therefore of a significant interest as a tool permitting to target this organelle with potentially therapeutic molecules and thus addressing a very important bulk of human pathologies linked with dysfunctions of mitochondrial translation machinery. |
