QM/MM Studies of Hairpin Ribozyme Self-cleavage Suggest the Feasibility of Multiple Competing Reaction Mechanisms
Overview
Affiliations
The hairpin ribozyme is a prominent member of small ribozymes since it does not require metal ions to achieve catalysis. Guanine 8 (G8) and adenine 38 (A38) have been identified as key participants in self-cleavage and -ligation. We have carried out hybrid quantum-mechanical/molecular mechanical (QM/MM) calculations to evaluate the energy along several putative reaction pathways. The error of our DFT description of the QM region was tested and shown to be ~1 kcal/mol. We find that self-cleavage of the hairpin ribozyme may follow several competing microscopic reaction mechanisms, all with calculated activation barriers in good agreement with those from experiment (20-21 kcal/mol). The initial nucleophilic attack of the A-1(2'-OH) group on the scissile phosphate is predicted to be rate-limiting in all these mechanisms. An unprotonated G8(-) (together with A38H(+)) yields a feasible activation barrier (20.4 kcal/mol). Proton transfer to a nonbridging phosphate oxygen also leads to feasible reaction pathways. Finally, our calculations consider thio-substitutions of one or both nonbridging oxygens of the scissile phosphate and predict that they have only a negligible effect on the reaction barrier, as observed experimentally.
Investigation of the p of the Nucleophilic O2' of the Hairpin Ribozyme.
Veenis A, Li P, Soudackov A, Hammes-Schiffer S, Bevilacqua P J Phys Chem B. 2021; 125(43):11869-11883.
PMID: 34695361 PMC: 8760728. DOI: 10.1021/acs.jpcb.1c06546.
RNA Structural Dynamics As Captured by Molecular Simulations: A Comprehensive Overview.
Sponer J, Bussi G, Krepl M, Banas P, Bottaro S, Cunha R Chem Rev. 2018; 118(8):4177-4338.
PMID: 29297679 PMC: 5920944. DOI: 10.1021/acs.chemrev.7b00427.
White N, Hoogstraten C Biophys Chem. 2017; 228:62-68.
PMID: 28710920 PMC: 5572644. DOI: 10.1016/j.bpc.2017.07.001.
Pressure modulates the self-cleavage step of the hairpin ribozyme.
Schuabb C, Kumar N, Pataraia S, Marx D, Winter R Nat Commun. 2017; 8:14661.
PMID: 28358002 PMC: 5379106. DOI: 10.1038/ncomms14661.
Understanding in-line probing experiments by modeling cleavage of nonreactive RNA nucleotides.
Mlynsky V, Bussi G RNA. 2017; 23(5):712-720.
PMID: 28202709 PMC: 5393180. DOI: 10.1261/rna.060442.116.