Hydrogen-bonding networks and RNA bases revealed by cryo electron microscopy suggest a triggering mechanism for calcium switches
10.1073/pnas.1018104108
Crossref journal-article
Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences (341)
Abstract

Helical assemblies such as filamentous viruses, flagella, and F-actin represent an important category of structures in biology. As the first discovered virus, tobacco mosaic virus (TMV) was at the center of virus research. Previously, the structure of TMV was solved at atomic detail by X-ray fiber diffraction but only for its dormant or high-calcium-concentration state, not its low-calcium-concentration state, which is relevant to viral assembly and disassembly inside host cells. Here we report a helical reconstruction of TMV in its calcium-free, metastable assembling state at 3.3 Å resolution by cryo electron microscopy, revealing both protein side chains and RNA bases. An atomic model was built de novo showing marked differences from the high-calcium, dormant-state structure. Although it could be argued that there might be inaccuracies in the latter structure derived from X-ray fiber diffraction, these differences can be interpreted as conformational changes effected by calcium-driven switches, a common regulatory mechanism in plant viruses. Our comparisons of the structures of the low- and high-calcium states indicate that hydrogen bonds formed by Asp116 and Arg92 in the place of the calcium ion of the dormant (high-calcium) state might trigger allosteric changes in the RNA base-binding pockets of the coat protein. In turn, the coat protein–RNA interactions in our structure favor an adenine-X-guanine (A*G) motif over the G*A motif of the dormant state, thus offering an explanation underlying viral assembly initiation by an AAG motif.

Bibliography

Ge, P., & Zhou, Z. H. (2011). Hydrogen-bonding networks and RNA bases revealed by cryo electron microscopy suggest a triggering mechanism for calcium switches. Proceedings of the National Academy of Sciences, 108(23), 9637–9642.

Authors 2
  1. Peng Ge (first)
  2. Z. Hong Zhou (additional)
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Dates
Type When
Created 14 years, 3 months ago (May 17, 2011, 11:34 p.m.)
Deposited 3 years, 2 months ago (June 7, 2022, 3:38 a.m.)
Indexed 1 month ago (July 25, 2025, 5:56 a.m.)
Issued 14 years, 3 months ago (May 17, 2011)
Published 14 years, 3 months ago (May 17, 2011)
Published Online 14 years, 3 months ago (May 17, 2011)
Published Print 14 years, 2 months ago (June 7, 2011)
Funders 0

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@article{Ge_2011, title={Hydrogen-bonding networks and RNA bases revealed by cryo electron microscopy suggest a triggering mechanism for calcium switches}, volume={108}, ISSN={1091-6490}, url={http://dx.doi.org/10.1073/pnas.1018104108}, DOI={10.1073/pnas.1018104108}, number={23}, journal={Proceedings of the National Academy of Sciences}, publisher={Proceedings of the National Academy of Sciences}, author={Ge, Peng and Zhou, Z. Hong}, year={2011}, month=may, pages={9637–9642} }