Potexvirus
Encyclopedia
Potexvirus is a genus of plant pathogenic viruses, belonging to the family Alphaflexiviridae
and the order Tymovirales
. Transmission
occurs mechanically, with viruses in this genus causing mosaic and ringspot symptom
s.
There are at least 25 viruses in this genus. A number of candidates for inclusion are also known (~20) but a decision to include these in the genus or not is still pending.
The genome is linear, 5.9-7 kilobases in length with a capped 5' end and a polyadenylated 3' end. The genome encodes 5 proteins. From left to right these proteins are: the viral replication protein that consists of a capping enzyme domain, a helicase-like domain, the RNA dependent RNA polymerase, three proteins - the triple gene block (TGB) 1, 2 and 3 - and the coat protein.
The RNA is translated giving rise to the viral RNA polymerase. This in turn produces a negative stranded template from which a series of subgenomic RNAs are generated. These subgenomic RNAs are then translated into the viral proteins.
The 5' end is ~80 nucleotides in length and typically begins with the sequence GAAAA.
In addition to its RNA polymerase activity, the viral RNA polymerase (molecular weight ~150 kiloDalton
s) also has methyltransferase
and RNA helicase activities.
The TGB proteins are conserved among the Allexivirus, Carlavirus
, Foveavirus, Furovirus
, Hordeivirus
, Pecluvirus
, Pomovirus
and Potexvirus genera. Their functions are a matter of active research.
TGB 1 (molecular weight 23 kDa) is a multifunctional protein. It has RNA helicase activity and seems to be involved in cell to cell movement.
The TGB 2 (molecular weight 11 kDa) and TGB 3 (molecular weight 10 kDa) proteins associate with the endoplasmic reticulum
.
The coat protein has a molecular weight of ~25kDa.
The 3' untranslated region is ~100 nucleotides in length.
Alphaflexiviridae
Alphaflexiviridae are single-stranded positive sense RNA plant viruses, belonging to the order Tymovirales and thus to group IV of the Baltimore classification of viruses.The Alphaflexiviridae family include the following genera:...
and the order Tymovirales
Tymovirales
The Tymovirales are a newly established order of viruses in the 2009 classification with four genera.This group consists of viruses which have sense single stranded RNA genomes without DNA intermediates.-External links:*ICTV Virus Taxonomy 2009...
. Transmission
Transmission (medicine)
In medicine and biology, transmission is the passing of a communicable disease from an infected host individual or group to a conspecific individual or group, regardless of whether the other individual was previously infected...
occurs mechanically, with viruses in this genus causing mosaic and ringspot symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s.
There are at least 25 viruses in this genus. A number of candidates for inclusion are also known (~20) but a decision to include these in the genus or not is still pending.
Virology
The virion length may vary considerably (between 470-1000 nanometers or more) and is 12-13 nm in diameter. The pitch of the helix is of the basic helix 3.3-3.7 nm (8-9 copies of the coat protein per turn). It is non-enveloped, flexuous and filamentous. The coat itself is composed of 1000-1500 copies of the coat protein.The genome is linear, 5.9-7 kilobases in length with a capped 5' end and a polyadenylated 3' end. The genome encodes 5 proteins. From left to right these proteins are: the viral replication protein that consists of a capping enzyme domain, a helicase-like domain, the RNA dependent RNA polymerase, three proteins - the triple gene block (TGB) 1, 2 and 3 - and the coat protein.
The RNA is translated giving rise to the viral RNA polymerase. This in turn produces a negative stranded template from which a series of subgenomic RNAs are generated. These subgenomic RNAs are then translated into the viral proteins.
The 5' end is ~80 nucleotides in length and typically begins with the sequence GAAAA.
In addition to its RNA polymerase activity, the viral RNA polymerase (molecular weight ~150 kiloDalton
Dalton
Dalton may refer to:-In Canada:* Dalton, Algoma District, Ontario* Dalton Armoury, a Canadian Forces facility primarily used by the Queen's Own Rifles of Canada- In the United Kingdom :* Dalton, Cumbria, England* Dalton, Dumfries and Galloway, Scotland...
s) also has methyltransferase
Methyltransferase
A methyltransferase is a type of transferase enzyme that transfers a methyl group from a donor to an acceptor.Methylation often occurs on nucleic bases in DNA or amino acids in protein structures...
and RNA helicase activities.
The TGB proteins are conserved among the Allexivirus, Carlavirus
Carlavirus
Carlavirus, also known as "Carnation latent virus group" is a genus of virus that infects plants. It contains thirty-five described species and twenty-nine tentative species..-Virology:...
, Foveavirus, Furovirus
Furovirus
The Furovirus genus consists of rod shaped viruses enclosing bipartite , single-stranded, positive-sense RNA genomes. The type species of the genus is the soil borne wheat mosaic virus or SBWMV. These viruses infect plants of the grass family as well as fungi, infecting fungal vectors of the...
, Hordeivirus
Hordeivirus
The Hordeivirus refers to a genus of a plant virus with currently no assigned family or order. Virus consists of a non-enveloped, helical, rod-shaped capsid. The viral gene is segmented into 4 parts of positive sense, single stranded RNA of about 9000-17400 nucleotides in length.-External links:*...
, Pecluvirus
Pecluvirus
The Pecluvirus is a genus of a virus of the family Virgaviridae. The virions are helical, non-enveloped, elongated and rod-shaped with a length of 245 nm - 160 nm and a width of 21 nm. The genome is segmented into two parts of linear, positive-sense, single-stranded RNA, 10400...
, Pomovirus
Pomovirus
The Pomovirus is a genus of a virus of the family Virgaviridae. Virions are non-enveloped, elongated and rod-shaped with a length of 100-300 nm and a width of 18-20 nm with helical spirals on both ends. The genome is a single piece of non-segmented linear, positive-sense, single-stranded...
and Potexvirus genera. Their functions are a matter of active research.
TGB 1 (molecular weight 23 kDa) is a multifunctional protein. It has RNA helicase activity and seems to be involved in cell to cell movement.
The TGB 2 (molecular weight 11 kDa) and TGB 3 (molecular weight 10 kDa) proteins associate with the endoplasmic reticulum
Endoplasmic reticulum
The endoplasmic reticulum is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae...
.
The coat protein has a molecular weight of ~25kDa.
The 3' untranslated region is ~100 nucleotides in length.