Structure/function studies on mitochondrial elongation factors: Site-directed mutagenesis is being carried out on the elongation factor (EF-Tu) that promotes the binding of aminoacyl-tRNA (aa-tRNA) to ribosomes during protein synthesis. This protein forms a complex with the structurally unusual tRNAs found in mammalian mitochondria. Mutagenesis will be used to determine what amino acid residues in this protein are important for the ability of EF-Tu to interact with aa-tRNAs. Work in collaboration with Dr. Jens Nyborg (Denmark) is designed to determine the 3-D structure of this protein complexed to aa-tRNA.
Initiation of protein synthesis in mammalian mitochondria: Biochemical approaches have allowed the identification of a single protein required for the initiation of protein synthesis in human mitochondria. Genomics approaches have now lead to the tentative identification of two additional proteins that may be required for this process. The genes for these additional proteins are being cloned for expression in bacteria. The properties and mechanism of action of these proteins will be examined using biochemical approaches.
Proteomics approaches to studies of mammalian mitochondrial ribosomes: Proteolytic digestions, mass spectrometry and data base analysis are being used to determine the entire protein composition of mammalian mitochondrial ribosomes. Cross-linking of initiation and elongation factors to these ribosomes will then be used to map their binding sites on the ribosome.