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]
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]
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]
Tectiviridae contains the following genera and species: [3]
Other unassigned phages: [8]
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]
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]
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]
Tectiviridae contains the following genera and species: [3]
Other unassigned phages: [8]