π-π Interactions in structural stability: role in RNA binding proteins

RNA binding proteins play significant roles in many bio-macromolecular systems. Aromatic amino acid residues are vital for several biological functions. In the present work, the influences of π-π interactions in RNA binding proteins are analyzed. There are a total of 3,396 π-residues in RNA binding proteins out of which 1,547, 1,241, and 608 are phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp), respectively. Among these 945, 634, and 356 Phe, Tyr, and Trp residues, respectively, are involved in π-π interactions. The observations indicate that majority of the aromatic residues in RNA binding proteins are involved in π-π interactions. Side chain-side chain π-π interactions are the predominant type of interactions in RNA binding proteins. These π-π interactions stabilize the core regions within RNA binding proteins. π-π interacting residues are evolutionary conserved. Residue-wise analysis indicates that π-π interacting residues have higher long-range contacts and hence they are important in the global conformational stability of these proteins.