fil.dr., Associate Professor
(1942 - 2005)
Mitochondria have a protein biosynthetic machinery that is very specialized, and very different from that found in eubacterial, archaebacteria or in higher organisms (eukaryotes). First of all, the genome of mitochondria encodes only very few proteins (in the order of 20). Most of these are involved in the energy-generation that is the main task of mitochondria. Secondly, the ribosomes of mitochondria are minimal ribosome, which in contrast to other known ribosomes, contain more protein than RNA. A cryo-EM reconstruction of human mitochondrial ribosomes reveals the overall organisation of such minimal ribosomes. Thirdly, the tRNAs used by the mitochondrial ribosomes are unorthodox. Some of them, especially those specific for the amino acid Ser, have significantly altered tRNAs. One of those is even missing a whole stem-loop structure (the D-stem and D-loop). For the organism C. elegans (nematode) most mitochondrial tRNAs have been shown to be minimal ones, some even missing major parts of the classical tRNA fold. This seems to be compensated for in elongation factors EF-Tu that are longer than normal.
We are interested in determining the crystal structures of mitochondrial elongation factor EF-Tu and its various complexes with GDP, GTP, elogation factor EF-Ts, and tRNA. This work is a collaboration between our group and the groups of Prof. Linda L. Spremulli, University of North Carolina at Chapel Hill, USA and of Prof. Kimisune Watanabe, University of Tokyo, Japan.
Until now we have determined the crystal structure of bovine mitochondrial EF-Tu in complex with GDP. This structure is very similar to the crystal structure of bacterial EF-Tu:GDP from Thermus aquaticus. We now also have well diffracting crystals of the complex of mitochondrial EF-Tu:EF-Ts.
