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Molecular basis for RNA polymerization by Qβ replicase

Nature Structural & Molecular Biology volume 19, pages 229237 (2012) | Download Citation

Abstract

Core Qβ replicase comprises the Qβ virus–encoded RNA-dependent RNA polymerase (β-subunit) and the host Escherichia coli translational elongation factors EF-Tu and EF-Ts. The functions of the host proteins in the viral replicase are not clear. Structural analyses of RNA polymerization by core Qβ replicase reveal that at the initiation stage, the 3′-adenine of the template RNA provides a stable platform for de novo initiation. EF-Tu in Qβ replicase forms a template exit channel with the β-subunit. At the elongation stages, the C-terminal region of the β-subunit, assisted by EF-Tu, splits the temporarily double-stranded RNA between the template and nascent RNAs before translocation of the single-stranded template RNA into the exit channel. Therefore, EF-Tu in Qβ replicase modulates RNA elongation processes in a distinct manner from its established function in protein synthesis.

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Acknowledgements

We thank A. Hamada for technical assistance. We thank the beamline staff of BL-17A (KEK) for technical assistance during data collection. This work was supported by grants to K.T. from the Precursory Research for Embryonic Science and Technology program of the Japan Science and Technology Agency, the Funding program for Next Generation World-Leading Researchers (NEXT program) of the Japan Society for the Promotion of Science, the Takeda Science Foundation, the Mochida Memorial Foundation for Medical and Pharmaceutical Research and the Cell Science Research Foundation.

Author information

Affiliations

  1. Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, Japan.

    • Daijiro Takeshita
    •  & Kozo Tomita
  2. Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Saitama, Japan.

    • Kozo Tomita

Authors

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Contributions

K.T. planned and designed the research, K.T. and D.T. designed the experiments, D.T. conducted the experiments and D.T. and K.T. analyzed the data, discussed the results and wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Kozo Tomita.

Supplementary information

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    Supplementary Text and Figures

    Supplementary Figures 1–4 and Supplementary Discussion

Videos

  1. 1.

    Supplementary Movie 1

    Splitting the dsRNA of the template and growing RNAs.

  2. 2.

    Supplementary Movie 2

    The template entrance and exit channels in core Qβ replicase.

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DOI

https://doi.org/10.1038/nsmb.2204