Role of lysine methylation in the activities of elongation factor 1α

Abstract

Previous work in our laboratory has demonstrated that 19% of the lysine residues in the protein synthesis elongation factor (EF-1α) are methylated when the factor is purified from the mycelial form of the fungus Mucor racemosus. However, the same factor, when purified from spores of M. racemosus, is largely unmethylated. Despite its widespread occurrence in a great number of basic proteins, the functional significance of lysine N-methylation remains poorly understood. Spore and mycelial forms of EF-1α were therefore compared in a series of assays to determine their relative affinities for various substrates and cofactors known to interact with the factor during the elongation cycle. The results suggested that hypomethylated and fully methylated EF-1α had equal affinities for GTP, aminoacyl-tRNA, and ribosomes. Also, methylation did not appear to affect the accuracy of translation in an in vitro system. However, experiments did suggest that methylation may affect the ability of the factor to form complexes with other subunits (EF-1βγ) which are known to enhance the overall rate of protein synthesis.