The Pospiviroidae are a family of
viroid
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economi ...
s, including the first viroid to be discovered,
PSTVd. Their secondary structure is key to their
biological activity
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...
. The classification of this family is based on differences in the conserved central region sequence.
The genome consists (in this order) of an LH terminal domain, a pathogenic domain, conserved central region (
pospiviroid RY motif stem loop), variable domain, and an RH terminal domain. ''Pospiviroidae'' replication occurs in an asymmetric fashion via host cell
RNA polymerase
In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that synthesizes RNA from a DNA template.
Using the enzyme helicase, RNAP locally opens the ...
,
RNase
Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the ...
, and
RNA ligase.
Taxonomy
The family contains the following genera:
* ''
Apscaviroid
The Pospiviroidae are a family of viroids, including the first viroid to be discovered, PSTVd. Their secondary structure is key to their biological activity. The classification of this family is based on differences in the conserved central reg ...
''
* ''
Cocadviroid''
* ''
Coleviroid''
* ''
Hostuviroid
Hostuviroid is a genus of viroid
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most caus ...
''
* ''
Pospiviroid
''Pospiviroid'' is a genus of viroid
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most ...
''
References
External links
ICTV Report: ''Pospiviroidae''
– extensive information on pospivirioidae and viroids.
Viroids
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