Talk abstracts

Talk on Friday 09:30-09:50pm submitted by Mary Anne Rubio

Mitochondrial Import of tRNA: an evolutionarily conserved pathway from yeast to humans

Mary Anne T. Rubio (Microbiology, The Ohio State University), Jesse Rinehart (Chenistry, Biochemistry and Biophysics, Yale University), Dieter Soll (Chenistry, Biochemistry and Biophysics, Yale University), Juan D. Alfonzo (Microbiology, Ohio State Biochemistry Program, The RNA group, The Ohio State U.)

Abstract:
Eukaryotic cells are divided into multiple membrane-bound compartments, including the mitochondrion - the energy factory of aerobic organisms. Mitochondria possess their own genome that can vary in size, DNA content and structural arrangement amongst eukaryotes. Due to a dearth of mitochondrial genes the majority of proteins, needed for organellar function, are encoded in the nucleus and subsequently imported into the mitochondria. Likewise, in many organisms, the mitochondrial genome has an incomplete set of tRNA genes needed for translation. In these cases, tRNAs are also imported from the cytosol as an essential step for mitochondrial biogenesis. Here we show the first example of natively imported tRNAs into rat and human mitochondria. We found that two out of three nucleus-encoded tRNAGln isoacceptors localize to the mitochondria in vivo as confirmed by sequencing. Furthermore, we demonstrate that, like in yeast, in vitro import into isolated mammalian mitochondria occurs in an efficient and specific manner in the absence of added cytosolic factors. We conclude that tRNA import into eukaryotic mitochondria is more widespread than previously thought and it involves pathways that are mechanistically conserved from yeast to humans. Our findings also have direct implications for the study of a number of mitochondrial tRNA mutations that are causally linked to human disease.

Keywords: tRNA, Import, Mitochondria