The crucial role of conserved intermolecular H-bonds inaccessible to the solvent in formation and stabilization of the TL5.5 SrRNA complex.

Analysis of the structures of two complexes of 5 S rRNA with homologous ribosomal proteins, Escherichia coli L25 and Thermus thermophilus TL5, revealed that amino acid residues interacting with RNA can be divided into two different groups. The first group consists of non-conserved residues, which form intermolecular hydrogen bonds accessible to solvent. The second group, comprised of strongly conserved residues, form intermolecular hydrogen bonds that are shielded from solvent.