| Ligamenvirales | |
|---|---|
Virus classification | |
| (unranked): | Virus |
| Realm: | Adnaviria |
| Kingdom: | Zilligvirae |
| Phylum: | Taleaviricota |
| Class: | Tokiviricetes |
| Order: | Ligamenvirales |
| Families | |
Ligamenvirales is an order of linear viruses that infectarchaea of the phylumThermoproteota (formerly Crenarchaeota) and have double-stranded DNA genomes.[1] The order was proposed byDavid Prangishvili and Mart Krupovic in 2012 and subsequently created by theInternational Committee on Taxonomy of Viruses (ICTV).[2]
The name is derived from theLatinligamen, meaningstring orthread.[citation needed]
There are four families in this order –Chiyouviridae,Lipothrixviridae,Rudiviridae andUngulaviridae.[2]
The virons are filamentous with a helicalnucleocapsid. At either end are attached either fibers or more complex structures involved in host adhesion.[3][4]
The major coat proteins of both lipothrixviruses and rudiviruses have an unusual four-helix bundle topology.[5][6][7][8] Thegenome is non-segmented linear double stranded DNA. Viruses from the two families share up to ten genes. The major difference between the two families is that members of the familyRudiviridae are not enveloped, whereas nucleocapsids of lipothrixviruses are surrounded by a lipid membrane. Furthermore, whereas the capsid of rudiviruses is constructed from a single major capsid protein, that of lipothrixviruses is formed from two paralogous major capsid proteins. In both groups of viruses, the major capsid proteins form a claw-like dimer (homodimer in rudiviruses and heterodimer in lipothrixviruses), which wraps around the dsDNA.[citation needed]
Members of theLigamenvirales are structurally related to archaeal viruses of the familyTristromaviridae which, similar to lipothrixviruses, encode two paralogous major capsid proteins with the same fold as in ligamenviruses.[9] Due to these structural similarities, orderLigamenvirales and familyTristromaviridae were proposed to be unified within a class 'Tokiviricetes' (toki means ‘thread’ in Georgian andviricetes is an official suffix for a virus class).[9]
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