ИСТИНА

Ribosomal RNA is methylated in all organisms. Modified rRNA residues are clustered in the ribosomal functional centers and interact with the ribosome ligands and other residues of rRNA within the same or with the partner ribosomal subunit. A subset of modified residues is universally conserved, as well as corresponding modifying enzymes. For other methylated nucleotides one can observe convergent evolution of the modification machinery in different lineages, paralleled with divergent evolution which goes via gene duplication and leads to diversification of methyltransferase target residues. Several illustrations of this process will be discussed.