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Cryo-EM reconstruction of Sulfolobus polyhedral virus 1 (SPV1)
Structural highlights
FunctionCAPS1_SPV1 VP4 self-assembles to form, together with capsid protein VP10, an icosahedral caspid of 87 nm in diameter, with a T=43 symmetry and composed of 420 hexamers and 12 pentamers (PubMed:31636205). VP4 proteins arrange into hexons, while VP10 proteins form the pentameric densities located at the 5-fold axes in the virion (PubMed:31636205). The stoichiometry of VP4:VP10 is 42:1 (PubMed:31636205).[1] Publication Abstract from PubMedStudies on viruses infecting archaea living in the most extreme environments continue to show a remarkable diversity of structures, suggesting that the sampling continues to be very sparse. We have used electron cryo-microscopy to study at 3.7-A resolution the structure of the Sulfolobus polyhedral virus 1 (SPV1), which was originally isolated from a hot, acidic spring in Beppu, Japan. The 2 capsid proteins with variant single jelly-roll folds form pentamers and hexamers which assemble into a T = 43 icosahedral shell. In contrast to tailed icosahedral double-stranded DNA (dsDNA) viruses infecting bacteria and archaea, and herpesviruses infecting animals and humans, where naked DNA is packed under very high pressure due to the repulsion between adjacent layers of DNA, the circular dsDNA in SPV1 is fully covered with a viral protein forming a nucleoprotein filament with attractive interactions between layers. Most strikingly, we have been able to show that the DNA is in an A-form, as it is in the filamentous viruses infecting hyperthermophilic acidophiles. Previous studies have suggested that DNA is in the B-form in bacteriophages, and our study is a direct visualization of the structure of DNA in an icosahedral virus. A packing for A-form DNA in an icosahedral virus.,Wang F, Liu Y, Su Z, Osinski T, de Oliveira GAP, Conway JF, Schouten S, Krupovic M, Prangishvili D, Egelman EH Proc Natl Acad Sci U S A. 2019 Oct 21. pii: 1908242116. doi:, 10.1073/pnas.1908242116. PMID:31636205[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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