RNA Kink-Turns as Flexible Molecular Elbows Relevant to Ribosome Function

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Authors

RÁZGA Filip ZACHARIAS Martin RÉBLOVÁ Kamila KOČA Jaroslav ŠPONER Jiří

Year of publication 2005
Type Article in Proceedings
Conference Strukturní biofyzika makromolekul
MU Faculty or unit

Faculty of Science

Citation
Field Physical chemistry and theoretical chemistry
Keywords Molecular Dynamics; RNA Kink Turn; Ribosome; RNA flexibility;
Description Explicit-solvent Molecular Dynamics (MD) simulations were carried out for three K-turns (Kt) from 23S rRNA, i.e., Kt-38 located at the A-site finger base, Kt-42 located at the L7/L12 stalk base, and Kt-58 located in Domain III and for K-turn of human U4 snRNA. The presence of K-turns at key functional sites in the ribosome (e.g., A-site finger and L7/L12 stalk) suggests that some K-turns can confer flexibility on RNA protuberances that regulate the traversal of tRNAs during translocation. MD simulations demonstrated that the K-turns can act as flexible molecular elbows. The angle between the helical arms is regulated by local variations of the second A-minor (type I) interaction, which mediates the contact between the helical stems, and by conformational change of the single base from the nominally unpaired region. Moreover, K-turns are associated with a unique network of long-residency and dynamical hydration sites that are intimately involved in modulating their conformational dynamics. Variability of A-minor interaction ranges from closed geometries to open ones stabilized by insertion of long-residency waters between the interacting bases. Implicit solvent conformational search confirms the flexibility of K-turns around their x-ray geometries and identifies a second separate low-energy region with more open structures that could correspond to K-turn geometries seen in solution experiments. An extended simulation of Kt-42 with the factor-binding site shows that elbow-like motion fully propagates beyond the K-turn and could mediate large-scale adjustments of distant RNA regions.
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