Cafeteria roenbergensis virus

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Cafeteria roenbergensis virus
The giant virus CroV with its virophage Mavirus at the lower left[1]
Virus classification Edit this classification
(unranked): Virus
Realm: Varidnaviria
Kingdom: Bamfordvirae
Phylum: Nucleocytoviricota
Class: Megaviricetes
Order: Imitervirales
Family: Mimiviridae
Genus: Cafeteriavirus
Species:
Cafeteria roenbergensis virus

Cafeteria roenbergensis virus (CroV) is a

bicosoecid flagellate Cafeteria roenbergensis
, a member of the microzooplankton community.

History

The virus was isolated from seawater samples collected from the Gulf of Mexico during 1989 to 1991, on a flagellate host that was misidentified as belonging to the genus Bodo; hence the original designation of the virus as BV-PW1. The virus was shown to be about 300 nm in diameter and have a complex internal structure, as well as evidence of a putative tail-like structure

Nucleocytoplasmic large DNA viruses.[5]
CroV is itself parasitized by a virophage named "Mavirus".[6][7]

Viral protein composition and structure

Cryo-EM images of CroV compared to APMV. (A) Cryo-electron micrograph of four CroV particles. (B) Single CroV particle with concave core depression (white arrow). (C) Single APMV particle. Scale bars in (A–C) represent 2,000 Å.
Cryo-EM reconstruction of the CroV virion and capsomer arrangements of other giant icosahedral viruses. (A) Reconstruction of the CroV capsid. The isosurface of the map was colored by pentasymmetrons (purple) and trisymmetrons (blue, red, green, cyan and orange). One of the 30 edges of the icosahedron is marked by a cyan line. Two surface areas (a,b) are magnified and selected capsomers are labeled by yellow triangles to show their orientations. (B–E) Isolated icosahedral faces of CroV, PBCV-1, CIV and PpV01 capsids are shown schematically. Their T-numbers, asymmetric unit capsomer numbers, and trisymmetron capsomer numbers are listed. 5-fold, 3-fold, and 2-fold symbols are indicated in red and ASUs are outlined in blue.

Viral protein composition includes 141 encoded proteins that have been identified in CroV, a number believed to be in close proximity to the entirety of the virion

cryo-electron microscopy yielded an icosahedral virus capsid with a T number of 499 and a new model for capsid assembly for giant viruses.[citation needed
]

Viral genome

A diagram of CroV's genome, showing the functional categories of what the genome encodes for, when in the viral life the genes are expressed, the types of promoters, as well as the types of repeats.

CroV is the sole member of the genus Cafeteriavirus in the family Mimiviridae within the proposed order Megavirales.

Acanthamoeba polyphaga mimivirus is its closest known relative, although the two viruses share less than one-third of homologous genes.[4]

The viral genome is primarily a 618,000 base pair strand flanked by large and highly repetitive repeats on both ends of the genome. These large caps are theorized to protect the ends of the protein-coding region, similar to

eukaryotes. Due to production of transcriptional genes, like that of tRNA synthetase, the virus is able to modify and regulate host translational machinery that results in CroV being less dependent on host-cell components. 5% of the genome consists of repetitive elements that serve a yet unknown purpose. A region of 38,000 bases was observed that is believed to be involved with carbohydrate metabolism. The virus contains pathways that help assist in the biosynthesis of KDO (3-deoxy-d-manno-octulosonate). The presence and expression of 10 genes involved in glycoprotein synthesis were identified, suggesting that CroV is able to potentially partake in virion-cell recognition.[4]

CroV also encodes several other interesting proteins. It encodes an entire biosynthetic pathway for the creation of

ubiquitination, which is a post-translational modification of proteins that functions in cellular signaling.[11]

Viral replication

VF is the “virus factory,” where replication of CroV occurs. The white arrowhead indicates newly formed CroV particles. The white long-stem arrows indicate mavirus, a virophage that infects CroV.

Viral reproduction occurs in large constructs known as large cytoplasmic factories or viral factories. This is the site where DNA

transcription, and particle assembly are thought to take place. These factories are also the primary targets of the virophage Mavirus, which utilizes CroV machinery to replicate. Mavirus is a 19,000 kb circular double stranded DNA virus. Maviral infection reduces host cell death by interfering with CroV infection and replication.[12] Mavirus integrates into the genome of cells of Cafeteria roenbergensis, and thereby confers immunity to the population.[13]

CroV enters cells via

tRNA, and translation initiation factors to fine-tune the translation to its own advantage.[4]

Host interaction

CroV infects Cafeteria roenbergensis, which is a marine zooflagellate. CroV is fatal to the host cell. This impacts coastal ecology because Cafeteria roenbergensis feeds on bacteria found in the water. When there are low numbers of Cafeteria roenbergensis due to extensive CroV infections, the bacterial populations rise exponentially.[4]

References

  1. doi:10.1371/journal.ppat.1007592. Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  2. doi:10.3354/ame009203
    .
  3. hdl:2429/14364
    .
  4. ^
    PMID 20974979
    .
  5. ^ Matthias Fischer. "Suttle Laboratory Marine Virology and Microbiology: Profile: Matthias Fischer". Suttle Laboratory. Retrieved 2010-10-26.
  6. ^ John Timmer. "A virus so large it gets viruses". Ars Technica. Retrieved 2010-03-05.
  7. S2CID 206530677
    .
  8. PMID 24973308
    .
  9. PMID 28710447
    .>
  10. PMID 23812617
    .
  11. PMID 21994725
    .
  12. S2CID 206530677
    .
  13. S2CID 4458402
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Cafeteria_roenbergensis_virus&oldid=1178444054"