Editing Extremophile (section)

==DNA transfer==
Over 65 prokaryotic species are known to be naturally competent for genetic transformation, the ability to transfer DNA from one cell to another cell followed by integration of the donor DNA into the recipient cell's chromosome.<ref>{{Cite journal |vauthors=Johnsborg O, Eldholm V, Håvarstein LS |date=December 2007 |title=Natural genetic transformation: prevalence, mechanisms and function |journal=Research in Microbiology |volume=158 |issue=10 |pages=767–78 |doi=10.1016/j.resmic.2007.09.004 |pmid=17997281|doi-access=free }}</ref> Several extremophiles are able to carry out species-specific DNA transfer, as described below.  However, it is not yet clear how common such a capability is among extremophiles.{{citation needed|date=May 2023}}

The bacterium ''[[Deinococcus radiodurans]]'' is one of the most radioresistant organisms known.  This bacterium can also survive cold, dehydration, vacuum and acid and is thus known as a polyextremophile.  ''D.&nbsp;radiodurans'' is competent to perform [[Transformation (genetics)|genetic transformation]].<ref>{{Cite journal |vauthors=Moseley BE, Setlow JK |date=September 1968 |title=Transformation in Micrococcus radiodurans and the ultraviolet sensitivity of its transforming DNA |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=61 |issue=1 |pages=176–83 |bibcode=1968PNAS...61..176M |doi=10.1073/pnas.61.1.176 |pmc=285920 |pmid=5303325 |doi-access=free}}</ref> Recipient cells are able to repair DNA damage in donor transforming DNA that had been UV irradiated as efficiently as they repair cellular DNA when the cells themselves are irradiated.  The extreme [[thermophile|thermophilic]] bacterium ''[[Thermus thermophilus]]'' and other related ''Thermus'' species are also capable of genetic transformation.<ref>{{Cite journal |vauthors=Koyama Y, Hoshino T, Tomizuka N, Furukawa K |date=April 1986 |title=Genetic transformation of the extreme thermophile Thermus thermophilus and of other Thermus spp |journal=Journal of Bacteriology |volume=166 |issue=1 |pages=338–40 |doi=10.1128/jb.166.1.338-340.1986 |pmc=214599 |pmid=3957870}}</ref>

''[[Halobacterium volcanii]]'', an extreme halophilic ([[salinity|saline]] tolerant) archaeon, is capable of natural genetic transformation.  Cytoplasmic bridges are formed between cells that appear to be used for DNA transfer from one cell to another in either direction.<ref>{{Cite journal |vauthors=Rosenshine I, Tchelet R, Mevarech M |date=September 1989 |title=The mechanism of DNA transfer in the mating system of an archaebacterium |journal=Science |volume=245 |issue=4924 |pages=1387–89 |bibcode=1989Sci...245.1387R |doi=10.1126/science.2818746 |pmid=2818746}}</ref>

''[[Sulfolobus solfataricus]]'' and ''[[Sulfolobus acidocaldarius]]'' are hyperthermophilic archaea. Exposure of these organisms to the DNA damaging agents UV irradiation, bleomycin or mitomycin C induces species-specific cellular aggregation.<ref name="Frols2008">{{Cite journal |display-authors=etal |vauthors=Fröls S, Ajon M, Wagner M, Teichmann D, Zolghadr B, Folea M, Boekema EJ, Driessen AJ, Schleper C, Albers SV |date=November 2008 |title=UV-inducible cellular aggregation of the hyperthermophilic archaeon Sulfolobus solfataricus is mediated by pili formation |url=https://www.rug.nl/research/portal/en/publications/uvinducible-cellular-aggregation-of-the-hyperthermophilic-archaeon-sulfolobus-solfataricus-is-mediated-by-pili-formation(0dd2a8eb-0f4b-4382-805d-158a870be95e).html |journal=Molecular Microbiology |volume=70 |issue=4 |pages=938–52 |doi=10.1111/j.1365-2958.2008.06459.x |pmid=18990182 |doi-access=free}}</ref><ref name="Ajon2011">{{Cite journal |display-authors=etal |vauthors=Ajon M, Fröls S, van Wolferen M, Stoecker K, Teichmann D, Driessen AJ, Grogan DW, Albers SV, Schleper C |date=November 2011 |title=UV-inducible DNA exchange in hyperthermophilic archaea mediated by type IV pili |url=https://pure.rug.nl/ws/files/6771142/2011MolMicrobiolAjon.pdf |journal=Molecular Microbiology |volume=82 |issue=4 |pages=807–17 |doi=10.1111/j.1365-2958.2011.07861.x |pmid=21999488 |doi-access=free |s2cid=42880145}}</ref> UV-induced cellular aggregation of ''S. acidocaldarius'' mediates chromosomal marker exchange with high frequency.<ref name="Ajon2011" /> Recombination rates exceed those of uninduced cultures by up to three orders of magnitude.  Frols et al.<ref name="Frols2008" /> and Ajon et al.<ref name="Ajon2011" /> hypothesized that cellular aggregation enhances species-specific DNA transfer between ''Sulfolobus'' cells in order to repair damaged DNA by means of homologous recombination.  Van Wolferen et al.<ref>{{Cite journal |vauthors=van Wolferen M, Ajon M, Driessen AJ, Albers SV |date=July 2013 |title=How hyperthermophiles adapt to change their lives: DNA exchange in extreme conditions |journal=Extremophiles |volume=17 |issue=4 |pages=545–63 |doi=10.1007/s00792-013-0552-6 |pmid=23712907 |s2cid=5572901}}</ref> noted that this DNA exchange process may be crucial under DNA damaging conditions such as high temperatures. It has also been suggested that DNA transfer in ''Sulfolobus'' may be an early form of sexual interaction similar to the more well-studied bacterial transformation systems that involve species-specific DNA transfer leading to homologous recombinational repair of DNA damage (and see [[Transformation (genetics)]]).{{Citation needed|date=December 2019|reason=removed citation to predatory publisher content}}

Extracellular membrane vesicles (MVs) might be involved in DNA transfer between different hyperthermophilic archaeal species.<ref name="Gaudin_viral">{{Cite journal |vauthors=Gaudin M, Krupovic M, Marguet E, Gauliard E, Cvirkaite-Krupovic V, Le Cam E, Oberto J, Forterre P |date=April 2014 |title=Extracellular membrane vesicles harbouring viral genomes |journal=Environmental Microbiology |volume=16 |issue=4 |pages=1167–75 |doi=10.1111/1462-2920.12235 |pmid=24034793|bibcode=2014EnvMi..16.1167G }}</ref> It has been shown that both [[plasmid]]s<ref>{{Cite journal |vauthors=Gaudin M, Gauliard E, Schouten S, Houel-Renault L, Lenormand P, Marguet E, Forterre P |date=February 2013 |title=Hyperthermophilic archaea produce membrane vesicles that can transfer DNA |journal=Environmental Microbiology Reports |volume=5 |issue=1 |pages=109–16 |doi=10.1111/j.1758-2229.2012.00348.x |pmid=23757139|bibcode=2013EnvMR...5..109G }}</ref> and viral [[genome]]s<ref name="Gaudin_viral" /> can be transferred via MVs. Notably, a horizontal plasmid transfer has been documented between hyperthermophilic ''[[Thermococcus]]'' and ''[[Methanocaldococcus]]'' species, respectively belonging to the orders ''Thermococcales'' and ''Methanococcales''.<ref>{{Cite journal |vauthors=Krupovic M, Gonnet M, Hania WB, Forterre P, Erauso G |year=2013 |title=Insights into dynamics of mobile genetic elements in hyperthermophilic environments from five new Thermococcus plasmids |journal=PLOS ONE |volume=8 |issue=1 |pages=e49044 |bibcode=2013PLoSO...849044K |doi=10.1371/journal.pone.0049044 |pmc=3543421 |pmid=23326305 |doi-access=free}}</ref>