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Updated: Jul 5, 2026

Structure of HIV-1 Capsid Assemblies by Cryo-electron Microscopy and Iterative Helical Real-space Reconstruction
Published on: August 9, 2011
Partitivirus structure reveals a 120-subunit, helix-rich capsid with distinctive surface arches formed by
Wendy F Ochoa1, Wendy M Havens, Robert S Sinkovits
1Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378, USA.
Abstract:
Two distinct partitiviruses, Penicillium stoloniferum viruses S and F, can be isolated from the fungus Penicillium stoloniferum. The bisegmented dsRNA genomes of these viruses are separately packaged in icosahedral capsids containing 120 coat-protein subunits. We used transmission electron cryomicroscopy and three-dimensional image reconstruction to determine the structure of Penicillium stoloniferum virus S at 7.3 A resolution. The capsid, approximately 350 A in outer diameter, contains 12 pentons, each of which is topped by five arched protrusions. Each of these protrusions is, in turn, formed by a quasisymmetric dimer of coat protein, for a total of 60 such dimers per particle. The density map shows numerous tubular features, characteristic of alpha helices and consistent with secondary structure predictions for the coat protein. This three-dimensional structure of a virus from the family Partitiviridae exhibits both similarities to and differences from the so-called "T = 2" capsids of other dsRNA viruses.
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