Avsunviroidae
Avsunviroidae | |
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Viroid of family Avsunviroidae | |
Virus classification | |
(unranked): | Virus |
Family: | Avsunviroidae |
Genera | |
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The Avsunviroidae are a family of
Replication
Replication occurs in the
Structure
Predictions of structure have suggested that they exist either as rod-shaped molecules with regions of base pairing causing formation of some hairpin loops or have branched configurations.[2][3]
The family has four stretches of conserved nucleotides, guuuc, uc, ucag, ac from 5' to 3', plus their Watson-Crick pairings on the other end of the loop. This is part of its hammerhead ribozyme.[1] Otherwise there is little structural similarity in the family.[Fl 1] They do not have the conserved CCH, TCR, or TCH motifs, which is one of the features defining their separation from the Pospiviroidae.[Fl 2]
Classification
The family has three genera, with a total of five species.[2]
- Family Avsunviroidae
- Genus Avsunviroid;[Fl 3]
- Species: Avocado sunblotch viroid (ASBVd, acc. J02020, gen. len. 247nt)[Fl 4]
- Genus Elaviroid;[Fl 5]
- Species: Eggplant latent viroid (ELVd, acc. AJ536613, gen. len. 333nt)[Fl 4]
- Genus Pelamoviroid;[Fl 6]
- Species: Appler hammerhead viroid, Chrysanthemum chlorotic mottle viroid (CChMVd, acc. Y14700, gen. len. 399nt)[Fl 4] and Peach latent mosaic viroid (PLMVd, acc. M83545, gen. len. 337nt)[Fl 4]
- Genus
Detection
The lack of a long, central conserved region makes Avsunviroidae harder to identify than Pospiviroidae. A method to detect them is to use their circularity: a computer can piece together many overlapping reads that appear to form repeats when placed linearly.[4]
References
- Flores, Ricardo; Hernández, Carmen; Alba, A. Emilio Martínez de; Daròs, José-Antonio; Serio, Francesco Di (2005). "Viroids and Viroid-Host Interactions". PMID 16078879.
- ^ p. 120, "Apart from the core nucleotides conserved in their hammerhead structures, no extensive sequence similarities exist between them"
- ^ p. 118-120, "The other four viroids, Avocado sunblotch viroid (ASBVd) (47), Peach latent mosaic viroid (PLMVd) (45), Chrysanthemum chlorotic mottle viroid (CChMVd) (65), and Eggplant latent viroid (ELVd) (30), do not have the conserved CCR, TCR, and TCH motifs but, remarkably, both their polarity strands self-cleave through hammerhead ribozymes; they form the second family, Avsunviroidae (reviewed in 33), whose type species is ASBVd (formal inclusion of ELVd in this family is pending ICTV approval) (Figure 1b)."
- ^ p. 120, "ASBVd, the only viroid with a high A + U content (62%) (47), forms a monospecific genus"
- ^ a b c d p. 119, TABLE 1
- ^ p. 120, "and ELVd, whose properties fall between those of the members of the other two genera, has been proposed to constitute its own genus (30).
- ^ p. 120, "but PLMVd and CChMVd are grouped in one genus because of their branched secondary structure (21, 45, 65), which is stabilized by a pseudoknot (10; S. Gago, M. De la Peňa & R. Flores, unpublished results) (Figure 1b), and their insolubility in2M LiCl (65)."
External links
- ICTV Online (10th) Report; Avsunviroidae
- MicrobiologyBytes: Viroids, archived from the original on 2007-02-24, retrieved 2007-03-16
- Description of Plant Viruses- Avsunviroidae, archived from the original on 2007-02-13, retrieved 2007-03-16
- STUDIES ON CATALYTIC RNA MOLECULES RELEVANT TO THE RNA WORLD HYPOTHESIS (PDF), archived from the original (PDF) on 2011-07-22