Occurrence and stability of anion–π interactions between phosphate and nucleobases in functional RNA molecules. Issue 20 (23rd November 2022)

• Record Type: Journal Article
• Authors: Chawla, Mohit; Kalra, Kanav; Cao, Zhen; Cavallo, Luigi; Oliva, Romina
• Is Part Of: Nucleic acids research. Volume 50:Issue 20(2022)
• Page Start: 11455
• Page End: 11469
• Publication Date: 2022-11-23
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkac1081
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: We present a systematic structural and energetic characterization of phosphate(OP)–nucleobase anion…π stacking interactions in RNAs. We observed OP–nucleobase stacking contacts in a variety of structural motifs other than regular helices and spanning broadly diverse sequence distances. Apart from the stacking between a phosphate and a guanine or a uracil two-residue upstream in specific U-turns, such interactions in RNA have been scarcely characterized to date. Our QM calculations showed an energy minimum at a distance between the OP atom and the nucleobase plane centroid slightly below 3 Å for all the nucleobases. By sliding the OP atom over the nucleobase plane we localized the optimal mutual positioning of the stacked moieties, corresponding to an energy minimum below -6 kcalmol −1, for all the nucleobases, consistently with the projections of the OP atoms over the different π-rings we observed in experimental occurrences. We also found that the strength of the interaction clearly correlates with its electrostatic component, pointing to it as the most relevant contribution. Finally, as OP–uracil and OP–guanine interactions represent together 86% of the instances we detected, we also proved their stability under dynamic conditions in model systems simulated by state-of-the art DFT-MD calculations.