Sulfolobus islandicus filamentous virus
Sulfolobus islandicus filamentous virus (SIFV) is an archaeal virus, classified in the family Lipothrixviridae within the order Ligamenvirales. The virus infects hypethermophilic and acidophilic archaeon Sulfolobus islandicus.[1]
| Sulfolobus islandicus filamentous virus | |
|---|---|
Virus classification  | |
| (unranked): | Virus |
| Realm: | Adnaviria |
| Kingdom: | Zilligvirae |
| Phylum: | Taleaviricota |
| Class: | Tokiviricetes |
| Order: | Ligamenvirales |
| Family: | Lipothrixviridae |
| Genus: | Betalipothrixvirus |
| Species: | Sulfolobus islandicus filamentous virus |
SIFV has a linear double-stranded DNA genome of 40,852 bp, which is the largest among characterized lipothrixviruses. The virions are enveloped filaments, nearly 2 micrometers in length. The nucleocapsid is formed from two paralogous major capsid proteins, which tightly wrap around the dsDNA genome; notably, dehydration of the genomic DNA by the major capsid proteins transforms the B-form DNA into A-form DNA.[2]
Life cycle
SIFV virions assemble inside the cell. Binding of the major capsid protein dimers to the linear dsDNA genome lead to the assembly of nucleocapsids, which are subsequently enveloped intracellularly through an unknown mechanism.[3] SIFV and probably other lipothrixviruses are lytic viruses. Virion release takes place through pyramidal portals, referred to as virus-associated pyramids (VAPs).[3] Unlike in the case of some other archaeal viruses (e.g., rudiviruses and turriviruses), the SIFV VAPs have a hexagonal base (i.e., constructed from six triangular facets). The VAPs can be as large as 220 nm at the base and are constructed from a single SIFV-encoded protein of 89 aa.[3] Expression of this protein in Escherichia coli leads to VAP formation in the inner bacterial membrane.
References
- Arnold, Hans Peter; Zillig, Wolfram; Ziese, Ulrike; et al. (2000). "A novel lipothrixvirus, SIFV, of the extremely thermophilic crenarchaeon Sulfolobus". Virology. 267 (2): 252–266. doi:10.1006/viro.1999.0105.
- Wang, F; Baquero, DP; Beltran, LC; Su, Z; Osinski, T; Zheng, W; Prangishvili, D; Krupovic, M; Egelman, EH (2020). "Structures of filamentous viruses infecting hyperthermophilic archaea explain DNA stabilization in extreme environments". Proceedings of the National Academy of Sciences of the United States of America. 117 (33): 19643–19652. doi:10.1073/pnas.2011125117. PMC 7443925. PMID 32759221.
- Baquero, DP; Gazi, AD; 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". Proceedings of the National Academy of Sciences of the United States of America. 118 (32): e2105540118. doi:10.1073/pnas.2105540118. PMC 8364153. PMID 34341107.