Expression and characterization of isoform 1 of human mitochondrial elongation factor G

Elongation factor G (EF-G) catalyzes the translocation step of protein biosynthesis. Genomic analysis suggests that two isoforms of this protein occur in mitochondria. The region of the cDNA coding for the mature sequence of isoform 1 of human mitochondrial EF-G (EF-G1(mt)) has been cloned and expressed in Escherichia coli. The recombinant protein has been purified to near homogeneity by chromatography on Ni-NTA resins and cation exchange high performance liquid chromatography. EF-G1(mt) is active on both bacterial and mitochondrial ribosomes. Human EF-G1(mt) is considerably more resistant to fusidic acid than many bacterial translocases. A molecular model for EF-G1(mt) has been created and analyzed in the context of its relationship to the translocases from other systems.