A filamentous archaeal virus is enveloped inside the cell and released through pyramidal portals
Baquero, D.P.; Gazi, A.D.; Sachse, M.; Liu, J.; Schmitt, C.; Moya-Nilges, M.; Schouten, S.; Prangishvili, D.; Krupovic, M. (2021). A filamentous archaeal virus is enveloped inside the cell and released through pyramidal portals. Proc. Natl. Acad. Sci. U.S.A. 118(32): e2105540118. https://dx.doi.org/10.1073/pnas.2105540118 In: Proceedings of the National Academy of Sciences of the United States of America. The Academy: Washington, D.C.. ISSN 0027-8424; e-ISSN 1091-6490, more |   |
| Author keywords | hyperthermophilic archaea; virus egress; virus assembly; archaeal viruses; cell lysis |
| Authors | | Top | - Baquero, D.P.
- Gazi, A.D.
- Sachse, M.
| - Liu, J.
- Schmitt, C.
- Moya-Nilges, M.
| - Schouten, S., more
- Prangishvili, D.
- Krupovic, M.
|
| Abstract | The majority of viruses infecting hyperthermophilic archaea display unique virion architectures and are evolutionarily unrelated to viruses of bacteria and eukaryotes. The lack of relationships to other known viruses suggests that the mechanisms of virus–host interaction in Archaea are also likely to be distinct. To gain insights into archaeal virus–host interactions, we studied the life cycle of the enveloped, ∼2-μm-longSulfolobus islandicus filamentous virus (SIFV), a member of the family Lipothrixviridae infecting a hyperthermophilic and acidophilic archaeon Saccharolobus islandicus LAL14/1. Using dual-axis electron tomography and convolutional neural network analysis, we characterize the life cycle of SIFV and show that the virions, which are nearly two times longer than the host cell diameter, are assembled in the cell cytoplasm, forming twisted virion bundles organized on a nonperfect hexagonal lattice. Remarkably, our results indicate that envelopment of the helical nucleocapsids takes place inside the cell rather than by budding as in the case of most other known enveloped viruses. The mature virions are released from the cell through large (up to 220 nm in diameter), six-sided pyramidal portals, which are built from multiple copies of a single 89-amino-acid-long viral protein gp43. The overexpression of this protein in Escherichia coli leads to pyramid formation in the bacterial membrane. Collectively, our results provide insights into the assembly and release of enveloped filamentous viruses and illuminate the evolution of virus–host interactions in Archaea. |
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