Methylation of proteins involved in translation

Abstract

SummaryMethylation is one of the most common protein modifications. Many different prokaryotic and eukaryotic proteins are methylated, including proteins involved in translation, including ribosomal proteins (RPs) and translation factors (TFs). Positions of the methylated residues in six Escherichia coli RPs and two Saccharomyces cerevisiae RPs have been determined. At least two RPs, L3 and L12, are methylated in both organisms. Both prokaryotic and eukaryotic elongation TFs (EF1A) are methylated at lysine residues, while both release factors are methylated at glutamine residues. The enzymes catalysing methylation reactions, protein methyltransferases (MTases), generally use S-adenosylmethionine as the methyl donor to add one to three methyl groups that, in case of arginine, can be asymetrically positioned. The biological significance of RP and TF methylation is poorly understood, and deletions of the MTase genes usually do not cause major phenotypes. Apparently methylation modulates intra-or intermolecular interactions of the target proteins or affects their affinity for RNA, and, thus, influences various cell processes, including transcriptional regulation, RNA processing, ribosome assembly, translation accuracy, protein nuclear trafficking and metabolism, and cellular signalling. Differential methylation of specific RPs and TFs in a number of organisms at different physiological states indicates that this modification may play a regulatory role.

The ribosome: A hot spot for the identification of new types of protein methyltransferases

“…In recent years, it has been recognized that proteins of the translational apparatus, including both ribosomal proteins and elongation factors, are major substrates for methylation reactions (5,7,8,19,28). These proteins, and the enzymes that modify them, have been extensively studied from the intersection of two research directions.…”

High-coverage proteome analysis reveals the first insight of protein modification systems in the pathogenic spirochete Leptospira interrogans

“…Posttranslational modifications (PTMs) play crucial roles in regulating protein functions in bacterial physiology and virulence [18][19][20]. In particular, phosphorylation, acetylation and methylation, which are the most extensively studied PTMs, are all acknowledged to be important for regulating protein activities [21][22][23].…”

Post-translational Modification of Ribosomal Proteins

“…Detailed analyses of eukaryote and prokaryote ribosomes by peptide mass spectrometry provide insights into the composition of ribosomal proteins and show a high degree of posttranslational modifications (1). These modifications are believed to extend molecular structures beyond the limits imposed by the 20 genetically encoded amino acids (2). For example, the Escherichia coli ribosomal protein S12 is shown to be post-translationally modified through 3-methylthiolation of the Asp-89 3 residue (Scheme 1A), a modification believed to improve translational accuracy (3,4).…”