''Ligamenvirales'' is an order of linear viruses that infect archaea of the phylum

Thermoproteota The Thermoproteota (also known as crenarchaea) are archaea that have been classified as a phylum of the Archaea domain. Initially, the Thermoproteota were thought to be sulfur-dependent extremophiles but recent studies have identified characteris ...

(formerly Crenarchaeota) and have double-stranded DNA genomes. The order was proposed by

David Prangishvili David Prangishvili (born 1948) is a virologist, Professor at the Pasteur Institute of Paris, and foremost authority on viruses infecting Archaea. Biography David Prangishvili gained a Master of Science degree in 1971 at Tbilisi State Universit ...

and Mart Krupovic in 2012 and subsequently created by the

International Committee on Taxonomy of Viruses The International Committee on Taxonomy of Viruses (ICTV) authorizes and organizes the taxonomic classification of and the nomenclatures for viruses. The ICTV has developed a universal taxonomic scheme for viruses, and thus has the means to ap ...

(ICTV). The name is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

{{lang, la, ligamen, meaning ''string'' or ''thread''.{{cn, date=November 2022

Taxonomy

There are three families in this order – ''

Lipothrixviridae ''Lipothrixviridae'' is a family of viruses in the order ''Ligamenvirales''. Thermophilic archaea in the phylum Thermoproteota serve as natural hosts. There are 11 species in this family, assigned to 4 genera. The genus Janekovic, D., Wunderl S ...

'', ''

Rudiviridae ''Rudiviridae'' is a family of viruses with linear double stranded DNA genomes that infect archaea. The viruses of this family are highly thermostable and can act as a template for site-selective and spatially controlled chemical modification. F ...

'' and '' Ungulaviridae''.{{cn, date=November 2022 The virons are filamentous with a helical nucleocapsid. At either end are attached either fibers or more complex structures involved in host adhesion.{{cn, date=November 2022 The major coat proteins of both lipothrixviruses and rudiviruses have an unusual four-

helix A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helic ...

bundle topology.Goulet A, Blangy S, Redder P, Prangishvili D, Felisberto-Rodrigues C, Forterre P, Campanacci V, Cambillau C (2009) Acidianus filamentous virus 1 coat proteins display a helical fold spanning the filamentous archaeal viruses lineage. PNAS 106 (50) 21155–60{{cite journal , last1=Liu , first1=Y , last2=Osinski , first2=T , last3=Wang , first3=F , last4=Krupovic , first4=M , last5=Schouten , first5=S , last6=Kasson , first6=P , last7=Prangishvili , first7=D , last8=Egelman , first8=EH , title=Structural conservation in a membrane-enveloped filamentous virus infecting a hyperthermophilic acidophile. , journal=Nature Communications , date=2018 , volume=9 , issue=1 , pages=3360 , doi=10.1038/s41467-018-05684-6 , pmid=30135568, pmc=6105669 , bibcode=2018NatCo...9.3360L The

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...

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 family ''Rudiviridae'' 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.{{cn, date=November 2022 Members of the ''Ligamenvirales'' are structurally related to archaeal viruses of the family ''

Tristromaviridae ''Tristromaviridae'' is a family of viruses. Archaea Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bact ...

'' which, similar to lipothrixviruses, encode two paralogous major capsid proteins with the same fold as in ligamenviruses.{{cite journal , last1=Wang , first1=Fengbin , last2=Baquero , first2=Diana P , last3=Su , first3=Zhangli , last4=Osinski , first4=Tomasz , last5=Prangishvili , first5=David , last6=Egelman , first6=Edward H , last7=Krupovic , first7=Mart , title=Structure of a filamentous virus uncovers familial ties within the archaeal virosphere , journal=Virus Evolution , date=2020 , volume=6 , issue=1 , pages=veaa023 , doi=10.1093/ve/veaa023 , pmid=32368353 , pmc=7189273 , url= Due to these structural similarities, order ''Ligamenvirales'' and family ''

'' were proposed to be unified within a class 'Tokiviricetes' (toki means ‘thread’ in Georgian and ''viricetes'' is an official suffix for a virus class).

References

{{Reflist {{Taxonbar, from=Q6545850 Archaeal viruses Virus orders