Recent advances in protein methylation: Enzymatic methylation of nucleic acid binding proteins
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Heterogeneous nuclear RNP protein A1, one of the major proteins in hnRNP particle (precursor for mRNA), is known to be post-translationally arginine-methylatedin vivo on residues 193, 205, 217 and 224 within the RGG box, the motif postulated to be an RNA binding domain. Possible effect of NG-arginine methyl-modification in the interaction of protein A1 to nucleic acid was investigated. The recombinant hnRNP protein A1 wasin vitro methylated by the purified nuclear protein/histone-specific protein methylase I (S-adenosylmethionine:protein-arginine N-methyltransferase) stoichiometrically and the relative binding affinity of the methylated and the unmethylated protein A1 to nucleic acid was compared: Differences in their binding properties to ssDNA-cellulose, pI values and trypsin sensitivities in the presence and absence of MS2-RNA all indicate that the binding property of hnRNP protein A1 to single-stranded nucleic acid has been significantly reduced subsequent to the methylation. These results suggest that posttranslational methyl group insertion to the arginine residue reduces protein-RNA interaction, perhaps due to interference of H-bonding between guanidino nitrogen arginine and phosphate RNA.
KeywordsProtein-arginine methylation Nucleic acid binding protein Protein methylase I S-adenosyl-L-methionine RGG motiff
heterogeneous ribonucleoprotein particle
myelin basic protein
high mobility group
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