| Tectiviridae | |
|---|---|
| |
| CryoEM model of Enterobacteria phage PRD1 capsid. PDB entry 1gw7 [1] | |
Virus classification
| |
| (unranked): | Virus |
| Realm: | Varidnaviria |
| Kingdom: | Bamfordvirae |
| Phylum: | Preplasmiviricota |
| Class: | Tectiliviricetes |
| Order: | Kalamavirales |
| Family: | Tectiviridae |
| Genera | |
Tectiviridae is a family of viruses with 10 species in five genera. Bacteria serve as natural hosts. [2] [3] Tectiviruses have no head-tail structure, but are capable of producing tail-like tubes of ~ 60×10 nm upon adsorption or after chloroform treatment. The name is derived from Latin tectus (meaning 'covered'). [4]
Virology
The virions of Tectiviridae species are non-enveloped, icosahedral and display a pseudo T=25 symmetry. [2] The capsid has two layers. The outer layer is a protein structure of 240 capsid proteins trimers, and the inner one is a proteinaceous lipid membrane which envelopes the virus genome. Apical spikes extending about 20 nanometers (nm) protrude from the icosahedrons vertices.[ citation needed]
The genome is a single molecule of linear double-stranded DNA of 15 kilo bases in length, and has 30 open reading frames. [2] It forms a tightly packed coil and encodes several structural proteins. It encodes about 30 proteins that are transcribed in operons. At least 9 structural proteins are present in the viron. The genome is about 66 mega daltons in weight and constitutes 14–15% of the virion by weight. Lipids constitute a further 15% by weight. Carbohydrates are not present.[ citation needed]
Life cycle
Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption into the host cell. [2] After adsorption to the host cell surface the virion extrudes a tail-tube structure through a vertex for genome delivery into the host. Replication follows the DNA strand displacement model. DNA-templated transcription is the method of transcription. [2] Capsid proteins polymerize around a lipoprotein vesicle translocated in the cytoplasm by virion assembly factors.
Mature virons are released by lysis, which, in the case of PRD1, is achieved with the aid of virus-encoded lysis machinery consisting of four proteins: P15 ( endolysin), [5] P35 (holin), [6] P36 and P37 (homologues of the Rz/Rz1 proteins of phage lambda). [7]
Taxonomy
Tectiviridae contains the following genera and species: [3]
Other unassigned phages: [8]
References
- ^ San Martín C, Huiskonen JT, Bamford JK, Butcher SJ, Fuller SD, Bamford DH, Burnett RM (2002). "Minor proteins, mobile arms and membrane-capsid interactions in the bacteriophage PRD1 capsid". Nature Structural Biology. 9 (10): 756–63. doi: 10.1038/nsb837. PMID 12219080. S2CID 32856328.
- ^ a b c d e "Viral Zone". ExPASy. Retrieved 15 June 2015.
- ^ a b "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 22 May 2021.
- ^ "ICTV Ninth Report; 2009 Taxonomy Release: Tectiviridae". ICTV. Archived from the original on 24 April 2019. Retrieved 18 September 2020.
- ^ Caldentey J, Hänninen AL, Bamford DH (1994). "Gene XV of bacteriophage PRD1 encodes a lytic enzyme with muramidase activity". Eur J Biochem. 225 (1): 341–346. doi: 10.1111/j.1432-1033.1994.00341.x. PMID 7925454.
- ^ Rydman PS, Bamford DH (2003). "Identification and mutational analysis of bacteriophage PRD1 holin protein P35". J Bacteriol. 185 (13): 3795–3803. doi: 10.1128/JB.185.13.3795-3803.2003. PMC 161566. PMID 12813073.
- ^ Krupovic M, Cvirkaite-Krupovic V, Bamford DH (2008). "Identification and functional analysis of the Rz/Rz1-like accessory lysis genes in the membrane-containing bacteriophage PRD1". Mol Microbiol. 68 (2): 492–503. doi: 10.1111/j.1365-2958.2008.06165.x. PMID 18366440.
- ^ Unclassified Tectiviridae. NCBI Taxonomy.
Further reading
- ICTVdB—The Universal Virus Database ICTVdB Management (2006). 00.068. Tectiviridae. In: ICTVdB—The Universal Virus Database, version 3. Büchen-Osmond, C. (Ed), Columbia University, New York, USA
- Virus Taxonomy: Eighth Report of the International Committee on Taxonomy of Viruses H.V. Van Regenmortel, D.H.L. Bishop, M. H. Van Regenmortel, Claude M. Fauquet (Eds)
- 68.0.1. Tectivirus Archived 28 September 2007 at the Wayback Machine