Arsenic biochemistry: Difference between revisions
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'''Arsenic DNA''' refers to [[microorganism]]s that have been proposed to use [[arsenic]] in their DNA and other vital cellular structures where all other known life uses [[phosphorus]]. It has been proposed that [[GFAJ-1]] displays such biochemistry. While some evidence has been presented, this proposal remains among [[hypothetical types of biochemistry]]. |
'''Arsenic DNA''' refers to [[microorganism]]s that have been proposed to use [[arsenic]] in their DNA and other vital cellular structures where all other known life uses [[phosphorus]]. It has been proposed that [[GFAJ-1]] displays such biochemistry. While some evidence has been presented, this proposal remains among [[hypothetical types of biochemistry]]. |
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Revision as of 11:31, 3 December 2010
 | This article documents a current event. Information may change rapidly as the event progresses, and initial news reports may be unreliable. The latest updates to this article may not reflect the most current information. |
Arsenic DNA refers to microorganisms that have been proposed to use arsenic in their DNA and other vital cellular structures where all other known life uses phosphorus. It has been proposed that GFAJ-1 displays such biochemistry. While some evidence has been presented, this proposal remains among hypothetical types of biochemistry.
Proposed organism
A research team lead by Felisa Wolfe-Simon has proposed that GFAJ-1 incorporates arsenic into its DNA and other cellular biochemistry where all other known life forms use phosphorous.[1][2][1][3][4] Further cellular, DNA-RNA, and genome research will follow.[5][6][7] This would constitute the first discovery of a life form capable of replacing one of the "big six" bioelements in its makeup,[5] which are: carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur.
Arsenic, which is chemically similar to phosphorus, while poisonous for most Earth life, is incorporated into the biochemistry of some organisms.[8] Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes (Chrysiogenes arsenatis).[9] Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy.
It has been speculated that the earliest life on Earth may have used arsenic in place of phosphorus in the backbone of its DNA.[10] A geomicrobiology study released by NASA has revealed that a bacterium named GFAJ-1, collected in the sediments of Mono Lake in eastern California, appears to employ such 'arsenic DNA' when cultured without phosphorus.[11][5][12][13][14]
At a NASA press conference to announce Wolfe-Simon's reults, Steven A. Benner expressed some skepticism that arsenate was substituted in for phosphate in the DNA backbone of these organisms unless other new mechanisms were present in the organism to prevent hydrolysis of the arsenic chemical bonds.[15] If the proposal is correct that bacterium GFAJ-1 uses arsenate in its DNA and other biomolecules, then it must have found a way to stabilize arsenate or otherwise work around this limitation. Wolfe-Simon speculates that this stability might be accomplished in part by isolating some arsenate containing molecules in large vacuole compartments rich in poly-β-hydroxybutyrate that GFAJ-1 develops when cultured in arsenic but not when cultured in phosphorus.[16][17]
See also
References
- ^ a b Bortman, Henry (5 October 2009). "Searching for Alien Life, on Earth". Astrobiology Magazine (NASA). Retrieved 2010-12-02.
- ^ Harvey, Mike (4 March 2010). "Could the Mono Lake arsenic prove there is a shadow biosphere?". UK: The Times. Retrieved 2010-12-02.
- ^ Palmer, Jason (2 December 2010). "Arsenic-loving bacteria may help in hunt for alien life". BBC News. Retrieved 2010-12-02.
- ^ Kottke, Jason (29 November 2010). "NASA news conference participants". Kottke.org. Retrieved 2010-12-02.
- ^ a b c Katsnelson, Alla (2 December 2010). "Arsenic-eating microbe may redefine chemistry of life". Nature News. doi:10.1038/news.2010.645. Retrieved 2010-12-02.
- ^ NASA.gov: "NASA-Funded Research Discovers Life Built With Toxic Chemical" — (December 2010)
- ^ NASA - Astrobiology Magazine: "Searching for Alien Life, on Earth" — (October 2009)
- ^ "Biochemical Periodic Table - Arsenic". Umbbd.msi.umn.edu. 2007-06-08. Retrieved 2010-05-29.
- ^ Niggemyer, A (2001). "Isolation and characterization of a novel As(V)-reducing bacterium: implications for arsenic mobilization and the genus Desulfitobacterium". Appl Environ Microbiol. 67 (12): 5568–80. doi:10.1128/AEM.67.12.5568-5580.2001. PMC 93345. PMID 11722908.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ Reilly, Michael (2008). "Early life could have relied on 'arsenic DNA'". New Scientist. 198 (2653): 10. doi:10.1016/S0262-4079(08)61007-6.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ "NASA-Funded Research Discovers Life Built With Toxic Chemical". NASA.gov. 2 December 2010. Retrieved 2010-12-02.
- ^ Wolfe-Simon, Felisa (2010-12-02). "A bacterium that can grow by using arsenic instead of phosphorus". Science. AAAS. doi:10.1126/science.1197258. Retrieved 2010-12-02.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Bortman, Henry (2010-12-02). "Arsenic-Eating Bacteria Opens New Possibilities for Alien Life". Space.Com web site. Retrieved 2010-12-02.
{{cite web}}: External link in|work= - ^ Dennis Overbye (December 2, 2010). "Thriving on Arsenic, a Microbe May Redefine Life". New York Times.
- ^ Bortman, Henry (2 December 2010). "How does an arsenic-based life-form work, exactly?". The Christian Science Monitor. Retrieved 2010-12-02.
- ^ Felisa Wolfe-Simon; et al. (2010-12-02). "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus". Science. doi:10.1126/science.1197258.
{{cite journal}}: Explicit use of et al. in:|author=(help) - ^ Thriving on Arsenic Henry Bortman, Astrobiology Magazine, 2010-12-02