Investigations on unconventional hydrogen bonds in RNA binding proteins: The role of CHOC interactions

摘要

We have investigated the roles played by CHOC interactions in RNA binding proteins. There was an average of 78 CHOC interactions per protein and also there was an average of one significant CHOC interaction for every 6 residues in the 59 RNA binding proteins studied. Main chain–Main chain (MM) CHOC interactions are the predominant type of interactions in RNA binding proteins. The donor atom contribution to CHOC interactions was mainly from aliphatic residues. The acceptor atom contribution for MM CHOC interactions was mainly from Val, Phe, Leu, Ile, Arg and Ala. The secondary structure preference analysis of CHOC interacting residues showed that, Arg, Gln, Glu and Tyr preferred to be in helix, while Ala, Asp, Cys, Gly, Ile, Leu, Lys, Met, Phe, Trp and Val preferred to be in strand conformation. Most of the CHOC interacting polar amino acid residues were solvent exposed while, majority of the CHOC interacting non polar residues were excluded from the solvent. Long and medium-range CHOC interactions are the predominant type of interactions in RNA binding proteins. More than 50% of CHOC interacting residues had a higher conservation score. Significant percentage of CHOC interacting residues had one or more stabilization centers. Sixty-six percent of the theoretically predicted stabilizing residues were also involved in CHOC interactions and hence these residues may also contribute additional stability to RNA binding proteins.