| 词条 | Tectivirus | ||||||||||||||||||||||||||||
| 释义 |
| name = Tectivirus | image = 1gw7.jpg | image_caption = CryoEM model of Enterobacteria phage PRD1 capsid. PDB entry {{PDBe|1gw7}}[1] | virus_group = i | taxon = Tectiviridae | subdivision_ranks = Genera | subdivision =Alpatectivirus Betatectivirus Gammatectivirus | type_species = Enterobacteria phage PRD1 }} Tectiviridae is a family of viruses with three genera. Gram-negative bacteria serve as natural hosts. There are currently four species in this genus including the type species Enterobacteria phage PRD1.[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.{{citation needed|date=June 2015}} The name is derived from Latin tectus (meaning 'covered'). VirologyThe 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. The genome is a single molecule of linear double-stranded DNA of 15 kilobases 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 megaDaltons in weight and constitutes 14–15% of the virion by weight. Lipids constitute a further 15% by weight. Carbohydrates are not present.
Life cycleViral 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),[4] P35 (holin),[5] P36 and P37 (homologues of the Rz/Rz1 proteins of phage lambda).[6]
TaxonomyTectiviruses have been classified into three major groups: (1) phages that infect Gram-negative bacteria (which lyse the host cell, not forming prophages) (2) those that infect Gram-positive bacteria (forming prophages) and (3) a virus that infects Gluconobacter cerinus. The tectivirus groups have a similar genome size and organization, but they have no detectable sequence similarity at the nucleotide level.[7] Three genera have been identified in this family: Alpatectivirus - infecting Enterobactericeae; Betatectivirus - infecting Gram positive bacteria; and Gammatectivirus. Examples[3]
References1. ^{{cite journal|pmid=12219080|year=2002|last1=San Martín|first1=C|last2=Huiskonen|first2=JT|last3=Bamford|first3=JK|last4=Butcher|first4=SJ|last5=Fuller|first5=SD|last6=Bamford|first6=DH|last7=Burnett|first7=RM|title=Minor proteins, mobile arms and membrane-capsid interactions in the bacteriophage PRD1 capsid|volume=9|issue=10|pages=756–63|doi=10.1038/nsb837|journal=Nature Structural Biology}} 2. ^1 2 3 4 {{cite web|title=Viral Zone|url=http://viralzone.expasy.org/all_by_species/579.html|publisher=ExPASy|accessdate=15 June 2015}} 3. ^1 {{cite web|last1=ICTV|title=Virus Taxonomy: 2014 Release|url=http://ictvonline.org/virusTaxonomy.asp|accessdate=15 June 2015}} 4. ^{{cite journal|title=Gene XV of bacteriophage PRD1 encodes a lytic enzyme with muramidase activity|journal=Eur J Biochem|year=1994|volume=225|issue=1|pages=341–346|doi=10.1111/j.1432-1033.1994.00341.x|pmid=7925454|vauthors=Caldentey J, Hänninen AL, Bamford DH }} 5. ^{{cite journal|title=Identification and mutational analysis of bacteriophage PRD1 holin protein P35|journal=J Bacteriol|year=2003|volume=185|issue=13|pages=3795–3803|doi=10.1128/JB.185.13.3795-3803.2003|pmid=12813073|vauthors=Rydman PS, Bamford DH |pmc=161566}} 6. ^{{cite journal|title=Identification and functional analysis of the Rz/Rz1-like accessory lysis genes in the membrane-containing bacteriophage PRD1|journal=Mol Microbiol|year=2008|volume=68|issue=2|pages=492–503|doi=10.1111/j.1365-2958.2008.06165.x|pmid=18366440|vauthors=Krupovic M, Cvirkaite-Krupovic V, Bamford DH }} 7. ^{{Cite journal|last=Saren|first=Ari-Matti|last2=Ravantti|first2=Janne J.|last3=Benson|first3=Stacy D.|last4=Burnett|first4=Roger M.|last5=Paulin|first5=Lars|last6=Bamford|first6=Dennis H.|last7=Bamford|first7=Jaana K. H.|date=2005-07-15|title=A Snapshot of Viral Evolution from Genome Analysis of the Tectiviridae Family|journal=Journal of Molecular Biology|volume=350|issue=3|pages=427–440|doi=10.1016/j.jmb.2005.04.059|pmid=15946683}} Further reading
External links
2 : Tectiviridae|Bacteriophages |
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