Structure
Volume 25, Issue 8, 1 August 2017, Pages 1303-1309.e3
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Short Article
Near-Atomic Resolution Structure of a Plant Geminivirus Determined by Electron Cryomicroscopy

https://doi.org/10.1016/j.str.2017.06.013Get rights and content
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Highlights

  • Determined the near-atomic structure of African cassava mosaic virus

  • Inter-capsomer contacts are mediated by capsid protein N termini and loop regions

  • Contacts between capsomers differed within half-capsids and at the waist

  • Identified a new pocket for possible DNA binding

Summary

African cassava mosaic virus is a whitefly-transmitted geminivirus which forms unique twin particles of incomplete icosahedra that are joined at five-fold vertices, building an unusual waist. How its 22 capsomers interact within a half-capsid or across the waist is unknown thus far. Using electron cryo-microscopy and image processing, we determined the virion structure with a resolution of 4.2 Å and built an atomic model for its capsid protein. The inter-capsomer contacts mediated by the flexible N termini and loop regions differed within the half-capsids and at the waist, explaining partly the unusual twin structure. The tip of the pentameric capsomer is sealed by a plug formed by a turn region harboring the evolutionary conserved residue Y193. Basic amino acid residues inside the capsid form a positively charged pocket next to the five-fold axis of the capsomer suitable for binding DNA. Within this pocket, density most likely corresponding to DNA was resolved.

Keywords

geminivirus
virus particles
electron cryomicroscopy
modeling
ACMV
image processing
structure

Cited by (0)

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Present address: Electron Microscopy Facility, Max Planck Institute for Developmental Biology, Spemannstr. 35, 72076 Tübingen, Germany

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Lead Contact