Open AccessStem-Loop V of Varkud Satellite RNA Exhibits Characteristics of the Mg2+ Bound Structure in the Presence of Monovalent Ions
Author(s) -
Christina Bergonzo,
Kathleen B. Hall,
Thomas E. Cheatham
Publication year - 2015
Publication title -
the journal of physical chemistry. b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 392
eISSN - 1520-6106
pISSN - 1520-5207
DOI - 10.1021/acs.jpcb.5b05190
Subject(s) - loop (graph theory) , ion , physics , satellite , rna , crystallography , chemistry , mathematics , biochemistry , combinatorics , quantum mechanics , astronomy , gene
The Varkud Satellite RNA contains a self-cleaving ribozyme that has been shown to function independently of its surroundings. This 160 nucleotide ribozyme adopts a catalytically active tertiary structure that includes a kissing hairpin complex formed by stem-loop I and stem-loop V (SLV). The five-nucleotide 5'-rUGACU loop of the isolated SLV has been shown to adopt a Mg(2+)-dependent U-turn structure by solution NMR. This U-turn hairpin is examined here by molecular dynamics simulations in the presence of monovalent and divalent ions. Simulations confirm on an all-atom level the hypotheses for the role of the Mg(2+) ions in stabilizing the loop, as well as the role of the solvent exposed U700 base. Additionally, these simulations suggest the Mg(2+)-free stem-loop adopts a wide range of structures, including energetically favorable structures similar to the Mg(2+)-bound loop structure. We propose this structure is a "gatekeeper" or precursor to Mg(2+) binding when those ions are present.