Satellite (biology)

Not to be confused with satellite chromosome or satellite DNA.

Satellite
In (a) is an orthorhombic crystal of satellite tobacco mosaic virus (STMV) that is more than 1.5 mm in length and was about 30 times the volume of any STMV crystal ever grown on Earth. It was grown in the Cryostat instrument on International Microgravity Laboratory-1. In (b) is an equivalent sized cubic crystal of the same virus, again, far exceeding in dimensions any grown in an Earth laboratory.
Scientific classification
(unranked):
Subviral agents
(unranked):
Satellite
Groups
  • Satellite viruses
  • Satellite nucleic acids

A satellite is a subviral agent that depends on the coinfection of a host cell with a helper virus for its replication. Satellites can be divided into two major classes: satellite viruses and satellite nucleic acids.[1] Satellite viruses, which are most commonly associated with plants, are also found in mammals, arthropods, and bacteria. They encode structural proteins to enclose their genetic material, which are therefore distinct from the structural proteins of their helper viruses.[1] Satellite nucleic acids, in contrast, do not encode their own structural proteins, but instead are encapsulated by proteins encoded by their helper viruses.[1][2] The genomes of satellites range upward from 359 nucleotides in length for satellite tobacco ringspot virus RNA (STobRV).[3]

Most viruses have the capability to use host enzymes or their own replication machinery to independently replicate their own viral RNA. Satellites, in contrast, are completely dependent on a helper virus for replication. The symbiotic relationship between a satellite and a helper virus to catalyze the replication of a satellite genome is also dependent on the host to provide components like replicases[4] to carry out replication.[5]

A satellite virus of mamavirus that inhibits the replication of its host has been termed a virophage.[6] However, the usage of this term remains controversial due to the lack of fundamental differences between virophages and classical satellite viruses.[7]

  1. ^ a b c Cite error: The named reference ICTV was invoked but never defined (see the help page).
  2. ^ Baez, John. "Subcellular Life Forms". University of California, Riverside. Retrieved 4 June 2020.
  3. ^ Wayne L. Gerlach; Jamal M. Buzayan; Irving R. Schneider; George Bruening (1986). "Satellite Tobacco Ringspot Virus RNA: Biological Activity of DNA Clones and Their in Vitro Transcripts". Virology. 151 (2): 172–185. doi:10.1016/0042-6822(86)90040-1. PMID 18640636.
  4. ^ Hu, Chung-Chi; Hsu, Yau-Heiu; Lin, Na-Sheng (18 December 2009). "Satellite RNAs and Satellite Viruses of Plants". Viruses. 1 (3): 1325–1350. doi:10.3390/v1031325. PMC 3185516. PMID 21994595.
  5. ^ Krupovic, Mart; Kuhn, Jens H.; Fischer, Matthias G. (1 January 2016). "A classification system for virophages and satellite viruses". Archives of Virology. 161 (1): 233–247. doi:10.1007/s00705-015-2622-9. hdl:11858/00-001M-0000-0028-DC34-F. ISSN 0304-8608. PMID 26446887.
  6. ^ Bernard La Scola; Christelle Desnues; Isabelle Pagnier; Catherine Robert; Lina Barrassi; Ghislain Fournous; Michèle Merchat; Marie Suzan-Monti; Patrick Forterre; Eugene Koonin & Didier Raoult (2008). "The virophage as a unique parasite of the giant mimivirus". Nature. 455 (7205): 100–4. Bibcode:2008Natur.455..100L. doi:10.1038/nature07218. PMID 18690211. S2CID 4422249.
  7. ^ Krupovic M; Cvirkaite-Krupovic V (2011). "Virophages or satellite viruses?". Nat Rev Microbiol. 9 (11): 762–763. doi:10.1038/nrmicro2676. PMID 22016897. S2CID 41271832.