Divalent ions tune the kinetics of a bacterial GTPase center rRNA folding transition from secondary to tertiary structure

Robb Welty, Suzette A. Pabit, Andrea M. Katz, George D. Calvey, Lois Pollack, Kathleen B. Hall

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Folding of an RNA from secondary to tertiary structure often depends on divalent ions for efficient electrostatic charge screening (nonspecific association) or binding (specific association). To measure how different divalent cations modify folding kinetics of the 60 nucleotide E. coli rRNA GTPase center, we combined stopped-flow fluorescence in the presence of Mg2+, Ca2+, or Sr2+ together with time-resolved small angle X-ray scattering (SAXS) in the presence of Mg2+ to observe the folding process. Immediately upon addition of each divalent ion, the RNA undergoes a transition from an extended state with secondary structure to a more compact structure. Subsequently, specific divalent ions modulate populations of intermediates in conformational ensembles along the folding pathway with transition times longer than 10 msec. Rate constants for the five folding transitions act on timescales from submillisecond to tens of seconds. The sensitivity of RNA tertiary structure to divalent cation identity affects all but the fastest events in RNA folding, and allowed us to identify those states that prefer Mg2+. The GTPase center RNA appears to have optimized its folding trajectory to specifically utilize this most abundant intracellular divalent ion.

Original languageEnglish
Pages (from-to)1828-1838
Number of pages11
JournalRNA
Volume24
Issue number12
DOIs
StatePublished - Dec 2018

Keywords

  • Kinetics
  • RNA folding
  • RRNA GTPase center
  • SAXS
  • Stopped-flow fluorescence

Fingerprint

Dive into the research topics of 'Divalent ions tune the kinetics of a bacterial GTPase center rRNA folding transition from secondary to tertiary structure'. Together they form a unique fingerprint.

Cite this