The functional exchangeability of pk- and k-turns in RNA structure

Peter Daldrop, Benoit Masquida, David M. J. Lilley

    Research output: Contribution to journalArticle

    6 Citations (Scopus)

    Abstract

    Ribonuclease P RNA requires a sharply kinked RNA helix to make a loop-receptor interaction that creates the binding site for the substrate. In some forms of the ribozyme, this is accomplished by a k-turn, while others have a different element called the pk-turn. The structure of the pk-turn in RNase P of Thermotoga maritima is globally very similar to a k-turn, but lacks all the standard features of that structure, including long-range hydrogen bonds between the two helical arms. We show here that in an isolated RNA duplex, the pk-turn fails to adopt a tightly kinked structure, but rather is a flexible element. This suggests that the tertiary contacts of RNase P assist its folding into the required kinked structure. We find that we can replace the k-turn of the SAM-I riboswitch with the pk-turn, such that the resulting RNA retains its ability to bind SAM, although with lower affinity. We also find that we can replace the pk-turn of T. maritima RNase P with a standard k-turn (in either orientation) with retention of ribozyme activity. Thus, although the pk-turn cannot intrinsically fold into the kinked structure, it can be induced to fold correctly in context. And the pk-turn and k-turns can substitute functionally for one another.

    Original languageEnglish
    Pages (from-to)445-452
    Number of pages8
    JournalRNA Biology
    Volume10
    Issue number3
    DOIs
    Publication statusPublished - Mar 2013

    Keywords

    • RNase P
    • BINDING
    • SAM-I riboswitch
    • MOTIF
    • RNA folding
    • CRYSTAL-STRUCTURE
    • LYSINE RIBOSWITCH
    • L7AE PROTEIN
    • ELEMENT
    • RNA structure
    • HELICAL JUNCTIONS
    • INDUCED FIT
    • SNRNA
    • NUCLEIC-ACIDS
    • kink turn

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