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| Title | Atomic Structure of the Trichomonas vaginalis Double-Stranded RNA Virus 2. |
|---|---|
| Journal, issue, pages | mBio, Vol. 12, Issue 2, Year 2021 |
| Publish date | Mar 30, 2021 |
 Authors | Alexander Stevens / Katherine Muratore / Yanxiang Cui / Patricia J Johnson / Z Hong Zhou /  |
| PubMed Abstract | , the causative pathogen for the most common nonviral sexually transmitted infection worldwide, is itself frequently infected with one or more of the four types of small double-stranded RNA (dsRNA) ..., the causative pathogen for the most common nonviral sexually transmitted infection worldwide, is itself frequently infected with one or more of the four types of small double-stranded RNA (dsRNA) viruses (TVV1 to 4, genus , family ). Each TVV encloses a nonsegmented genome within a single-layered capsid and replicates entirely intracellularly, like many dsRNA viruses, and unlike those in the family. Here, we have determined the structure of TVV2 by cryo-electron microscopy (cryoEM) at 3.6 Å resolution and derived an atomic model of its capsid. TVV2 has an icosahedral, T = 2*, capsid comprised of 60 copies of the icosahedral asymmetric unit (a dimer of the two capsid shell protein [CSP] conformers, CSP-A and CSP-B), typical of icosahedral dsRNA virus capsids. However, unlike the robust CSP-interlocking interactions such as the use of auxiliary "clamping" proteins among , only lateral CSP interactions are observed in TVV2, consistent with an assembly strategy optimized for TVVs' intracellular-only replication cycles within their protozoan host. The atomic model reveals both a mostly negatively charged capsid interior, which is conducive to movement of the loosely packed genome, and channels at the 5-fold vertices, which we suggest as routes of mRNA release during transcription. Structural comparison of TVV2 to the L-A virus reveals a conserved helix-rich fold within the CSP and putative guanylyltransferase domain along the capsid exterior, suggesting conserved mRNA maintenance strategies among This first atomic structure of a TVV provides a framework to guide future biochemical investigations into the interplay between and its viruses. viruses (TVVs) are double-stranded RNA (dsRNA) viruses that cohabitate in , the causative pathogen of trichomoniasis, the most common nonviral sexually transmitted disease worldwide. Featuring an unsegmented dsRNA genome encoding a single capsid shell protein (CSP), TVVs contrast with multisegmented dsRNA viruses, such as the diarrhea-causing rotavirus, whose larger genome is split into 10 dsRNA segments encoding 5 unique capsid proteins. To determine how TVVs incorporate the requisite functionalities for viral replication into their limited proteome, we derived the atomic model of TVV2, a first for TVVs. Our results reveal the intersubunit interactions driving CSP association for capsid assembly and the properties that govern organization and maintenance of the viral genome. Structural comparison between TVV2 capsids and those of distantly related dsRNA viruses indicates conserved strategies of nascent RNA release and a putative viral guanylyltransferase domain implicated in the cytoplasmic maintenance of viral messenger and genomic RNA. |
 External links | mBio / PubMed:33785622 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 4.0 Å |
| Structure data | EMDB-23560: 5-fold sub-particle reconstruction from Trichomonas vaginalis virus 2 capsid EMDB-23561: CryoEM structure of T. vaginalis virus 2 capsid |
| Source |
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 Keywords |  VIRAL PROTEIN / Capsid |
trichomonas vaginalis virus 2