Notes on Genus: Hordeivirus
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rigid rods
Type member: Barley stripe mosaic virus
Contents
- Members of this Genus
- General Description
- Morphology
- Electron Micrograph
- Genome
- Genus Genomic Organization
- Genome Map
- Type Member Genomic Organization
- All Known Sequences
- Curated Sequences
General Description
The genus Hordeivirus derives its name from the scientific name (Hordeum) of the host of the type member, barley stripe mosaic virus. Viruses in this genus have rigid rod shaped particles of (usually) three lengths up to 150 nm and a tripartite genome. They are transmitted through seeds.Morphology
Virions rigid rod-shaped, not enveloped, 20-25 nm in diameter and of three lengths: 150-160 nm (B), 126 nm (M) and 109 nm (T). The nucleocapsids are longitudinally striated.Genome
Tri- (or possibly quadri-) partite, linear, single stranded, positive sense RNA distributed among the different lengths of particle.Genus Genomic Organization
Only the type member has been fully sequenced and this has RNAs of c. 3800 (RNA1), 3300 (RNA2) and 2900-3200 (RNA3) nucleotides. A fourth RNA of 800-2000 nucleotides may be a subgenomic. The 3' terminus of each RNA has a poly(A) tract (of 8-40 nucleotides length) and a tRNA-like structure (of 236-238 nucleotides which accepts tyrosine). The 5' terminus has a methylated nucleotide cap with the sequence m7G5pppGUA. There are a total of 7 open reading frames:- RNA1 encodes a replication protein
- RNA2 encodes the coat protein (at the 5'-end) followed by a triple-gene-block (probably involved in cell-to-cell movement)
- RNA3 encodes a polymerase and a cysteine-rich protein
Type Member Genomic Organization
There are a total of 7 open reading frames:RNA1 (alpha) has a single open reading frame: | ||
1. | 130 kDa | Replication protein |
RNA2 (beta) has four open reading frames: | ||
2. | 22 kDa | Coat protein |
3. | 58 kDa | Triple gene block involved in cell-to-cell movement |
4. | 17 kDa | |
5. | 14 kDa | |
RNA3 (gamma) has two open reading frames: | ||
6. | 87 kDa | Polymerase |
7. | 17 kDa | Cysteine-rich protein, probably expressed from a subgenomic RNA |