The kink-turn motif in RNA is dimorphic, and metal ion-dependent

Terry A. Goody, Sonya E. Melcher, David G. Norman, David M.J. Lilley (Lead / Corresponding author)

    Research output: Contribution to journalArticlepeer-review

    134 Citations (Scopus)


    The kink-turn (K-turn) is a new motif in RNA structure that was identified by examination of the crystal structures of the ribosome. We examined the structural and dynamic properties of this element in free solution. The K-turn RNA exists in a dynamic equilibrium between a tightly kinked conformation and a more open structure similar to a simple bulge bend. The highly kinked form is stabilized by the noncooperative binding of metal ions, but a significant population of the less-kinked form is present even in the presence of relatively high concentrations of divalent metal ions. The conformation of the tightly kinked population is in excellent agreement with that of the K-turn structures observed in the ribosome by crystallography. The end-to-end FRET efficiency of this species agrees closely with that of the ribosomal K-turn, and the direction of the bend measured by comparative gel electrophoresis also corresponds very well. These results show that the tightly kinked conformation of the K-turn requires stabilization by other factors, possibly by protein binding, for example. The K-turn is therefore unlikely to be of itself a primary organizing feature in RNA.

    Original languageEnglish
    Pages (from-to)254-264
    Number of pages11
    Issue number2
    Publication statusPublished - Feb 2004


    • FRET
    • K-turn motif
    • Metal ions
    • RNA folding
    • RNA structure

    ASJC Scopus subject areas

    • Molecular Biology


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