Tectiviridae

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Tectiviridae
Systematics
Classification : Viruses
Area : Varidnaviria
Empire : Bamfordvirae
Phylum : Preplasmiviricota
Class : Tectiliviricetes
Order : Kalamavirales
Family : Tectiviridae
Genre : α, β, γ tectivirus
Taxonomic characteristics
Genome : dsDNA linear
Baltimore : Group 1
Symmetry : icosahedral
Cover : no
Left

The virus family Tectiviridae ( lat.tectus : covered) comprises only three genera Alphatectivirus , Betatectivirus and Gammatectivirus - the former genus Tectivirus has since been split up by the International Committee on Taxonomy of Viruses (ICTV). These are bacteriophages with a linear, double-stranded DNA genome and an icosahedral capsid with a diameter of 66 nm and consisting of 240 capsomeres ; the capsomeres consist of trimers of the capsid protein P3. The uncovered capsid has a fiber-like extension ( spike , peplomer ) about 20 nm long at the corners of the icosahedral symmetry , which is made up of two proteins (P2 and P5) and anchored to a penton protein at the base .

Inside (!) The capsid there is a lipid membrane vesicle, which consists of virus proteins and the lipid membrane of the host bacterium. To discharge the DNA genome, a tail-like tube of approx. 60 × 10 nm is everted through the capsid from the inner membrane vesicle (hence the name Tecti for the property of this "hidden" injection device ). This unusual structure of a membrane vesicle within an icosahedral capsid is shared by the Tevtiviridae with the family Corticoviridae . The genome is packaged in a coiled form within the membrane vesicle. The double-stranded DNA of the Tectiviridae is about 15 kBp in size and covalently linked to proteins at its 5 'ends ; the prototype of the family, the Enterobacteria phage PRD1 , codes for 25 virus proteins.

Systematics

According to ICTV Master Species List 2018b.v2 from March 2019:

  • Family Tectiviridae
  • Genus Alphatectivirus
  • Genus Betatectivirus
  • Genus Gammatectivirus
not classified within the family:
  • Species " Rhodococcus phage Toil "
  • Species " Thermus Phage P37-14 " (official status revoked by ICTV, as gene sequence is missing)
See also NCBI.

particularities

  • The hosts of the Tectiviridae are mesophilic bacteria. Only the species Thermus Phage p37-14 infects thermophilic bacteria and can be found in volcanic springs and geysers .
  • Enterobacteria Phage PRD1 in particular shows very many similarities to members of the Adenoviridae with regard to the capsid structure (trimeric hexagonal capsomers, pentons, fibers) and the genome organization (linear dsDNA, so-called inverted terminal repeats , terminal proteins, DNA polymerase type B). These similarities indicate a common origin, ie they are based on homology. Both families were therefore placed in the same class Tectiliviricetes by the ICTV in March 2020 .

literature

  • CM Fauquet, MA Mayo et al .: Eighth Report of the International Committee on Taxonomy of Viruses , London, San Diego, 2004
  • David M. Knipe, Peter M. Howley, et al. (eds.): Fields' Virology , 4th Edition, Philadelphia 2001

Web links

Individual evidence

  1. a b c d e f ICTV: ICTV Taxonomy history: Pseudomonas virus PRD1 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  2. ICTV: Master Species List 2018b.v2 # 34, March 2019
  3. ICTV: MSL 2018b.v2 , March 2019
  4. SIB: Alphatectivirus , on: ViralZone
  5. NCBI: Alphatectivirus (genus)
  6. a b c Natalya Yutin, Disa Bäckström, Thijs JG Ettema, Mart Krupovic, Eugene V. Koonin: Vast diversity of prokaryotic virus genomes encoding double jelly-roll major capsid proteins uncovered by genomic and metagenomic sequence analysis , in: Virol Jv.15 ; April 10, 2018, PMC 5894146 (free full text), PMID 29636073 , doi: 10.1186 / s12985-018-0974-y
  7. a b Céline Verheust, Nadine Fornelos, Jacques Mahillon: GIL16, a New Gram-Positive Tectiviral Phage Related to the Bacillus thuringiensis GIL01 and the Bacillus cereus pBClin15 Elements , in: J Bacteriol. 187 (6), March 2005, pp. 1966–1973, doi: 10.1128 / JB.187.6.1966-1973.2005 , PMC 1064052 (free full text).
  8. NCBI: Enterobacteria phage PR772 (no rank)
  9. SIB: Betatectivirus , on: ViralZone
  10. NCBI: Betatectivirus (genus)
  11. NCBI: Bacillus virus Bam35 (species)
  12. NCBI. Bacillus virus Wip1 (species)
  13. NCBI: Gammatectivirus (genus)
  14. NCBI: Rhodococcus phage Toil (species)
  15. Proposal 2017.013B
  16. NCBI: unclassified Tectiviridae
  17. Patrick Forterre : Evolution: The True Nature of Viruses , in: Spectrum August 2017, p. 37 (online article from July 19, 2017)