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Open Access

Structured mRNA induces the ribosome into a hyper‐rotated state

Peiwu Qin, Dongmei Yu, Xiaobing Zuo, Peter V Cornish

Author Affiliations

  1. Peiwu Qin1,
  2. Dongmei Yu2,3,
  3. Xiaobing Zuo4 and
  4. Peter V Cornish*,1,2,3
  1. 1Department of Biochemistry, University of Missouri, Columbia, MO, USA
  2. 2Department of Biological Engineering, University of Missouri, Columbia, MO, USA
  3. 3Informatics Institute University of Missouri, Columbia, MO, USA
  4. 4X‐ray Science Division, Argonne National Laboratory, Argonne, IL, USA
  1. *Corresponding author. Tel: +1 573 882 0443; Fax: +1 573 882 5635; E‐mail: cornishp{at}missouri.edu
  1. PQ and DY performed single molecule FRET experiments and analyzed data; PQ and PVC designed the project; XZ assisted with the SAXS data collection and analysis; PQ, XZ and PVC wrote the manuscript.

Abstract

During protein synthesis, mRNA and tRNA are moved through the ribosome by the process of translocation. The small diameter of the mRNA entrance tunnel only permits unstructured mRNA to pass through. However, there are structured elements within mRNA that present a barrier for translocation that must be unwound. The ribosome has been shown to unwind RNA in the absence of additional factors, but the mechanism remains unclear. Here, we show using single molecule Förster resonance energy transfer and small angle X‐ray scattering experiments a new global conformational state of the ribosome. In the presence of the frameshift inducing dnaX hairpin, the ribosomal subunits are driven into a hyper‐rotated state and the L1 stalk is predominantly in an open conformation. This previously unobserved conformational state provides structural insight into the helicase activity of the ribosome and may have important implications for understanding the mechanism of reading frame maintenance.

Synopsis

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Using smFRET and small angle X‐ray scattering (SAXS) experiments, we investigate the influence of structured mRNA on the conformational dynamics of the ribosome. We observe that upon interaction with structured elements, the small subunit is driven into a hyper‐rotated state and the frequency of intersubunit motion is reduced.

  • mRNA structure induces hyper‐rotation of the 30S ribosomal subunit.

  • The L1 stalk remains open in the presence of structured mRNA.

  • L1 stalk motion and subunit rotation are not strictly coupled.

Footnotes

  • The authors declare that they have no conflict of interest.

  • Received July 15, 2013.
  • Revision received November 20, 2013.
  • Accepted November 25, 2013.

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