Biology:Methanopyrus

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Short description: Genus of archaea

Methanopyrus
Scientific classification edit
Domain: Archaea
Kingdom: Euryarchaeota
Class: Methanopyri
Order: Methanopyrales
Huber and Stetter 2002
Family: Methanopyraceae
Huber and Stetter 2002
Genus: Methanopyrus
Kurr et al. 1992
Species:
M. kandleri
Binomial name
Methanopyrus kandleri
Kurr et al. 1992

Methanopyrus is a genus of methanogen,[1] with a single described species, Methanopyrus kandleri. It is a rod-shaped hyperthermophile, discovered on the wall of a black smoker from the Gulf of California at a depth of 2,000 m, at temperatures of 84–110 °C. Strain 116 was discovered in black smoker fluid of the Kairei hydrothermal field; it can survive and reproduce at 122 °C.[2] M. kandleri also requires a high ionic concentration (>1 M) in order for growth and cellular activity.[3] Due to the species' high resilience and extreme environment, M. kandleri is also classified as an extremophile.[3] It lives in a hydrogen-carbon dioxide rich environment, and like other methanogens reduces the latter to methane. It is placed among the Euryarchaeota, in its own class.

Microbiological characteristics

Morphology

Methanopyrus kandleri is a rod-shaped methanogen with an approximate length of 2-14 μm and diameter of 0.5 μm.[3] The cellular membrane of M. kandleri is unique as it consists of terpenoid lipids, believed to be one of the most primitive lipids and a predecessor to phytanyl di-ethers found in later archaea.[3] Terpenoid lipids are a group of lipids containing cholesterol, hopanoids, carotenoid, phytane, and bisphytane.[4] Although terpenoids are the main component of the membrane in M. kandleri, they are more of a supporting structure in eukaryote and bacteria.[4] M. kandleri is motile via polar flagella tufts.[5]

Methanopyrus kandleri has a high concentration of cyclic 2,3-diphosphoglycerate.[3] This compound is often found in hyperthermophile, helping to prevent protein denaturation in high temperatures.[6] The increased concentration of cyclic 2,3-diphosphoglycerate protects the methanogen, helping it survive in an environment that many other organisms could not. Beyond this compound to help protect the proteins, M. kandleri also has a high salt concentration inside its membrane.[3] This increased concentration of salt helps with enzyme stability and promotes activity of the enzymes at higher temperatures.[7]

Metabolism

As a methanogen, M. kandleri utilizes hydrogen as an electron source and reduces carbon dioxide from the environment into methane, a process known as methanogenesis.[3] M. kandleri is a chemolithoautotrophic, obligate anaerobe and does not use oxygen as a final electron acceptor.[3][7]

Habitat

Cultures of M. kandleri have been isolated from various submarine hydrothermal vents from locations in the Gulf of California, Central Indian Ridge, Mid-Atlantic Ridge, and Iceland.[5] The species was first discovered on the wall of a black smoker from the Gulf of California at a depth of 2,000 m, at temperatures of 84–110 °C. M. kandleri can survive up to temperatures of 122 °C, although optimal growth has been determined to be at 98 °C.[3][2] High internal ionic cell concentrations (>1 M) are required for cell growth and activity.[5] Due to the extremity of environment that M. kandleri resides in, it is hypothesized that further phylogenetic isolation has occurred due to the exclusivity of the species niche.[2]

Genomic properties

The complete genome of Methanopyrus kandleri was sequenced by researchers at Fidelity Systems. It was determined to be a GC-rich genome containing 1,694,969 nucleotides of which about 62.1% is guanine or cytosine.[3] The single circular chromosome possesses 1,691 protein-coding genes and 39 RNA genes.[3] The species also possesses a large number of orphan genes, possibly through viral gene transfer.[8]

Future research

Methanopyrus kandleri is also the only species known to have topoisomerase V. Topoisomerase V allows for M. kandleri to survive in such high temperatures and helps to relax both positively and negatively supercoiled DNA .[8] Topoisomerase V is a unique enzyme because it possesses both topoisomerase and DNA repair activities, specifically multiple DNA repair sites that can act independently of each other even if there is damage to one of the sites on the DNA.[9] Although topoisomerase V is useful in this case, finding other hyperthermophiles that have topoisomerase V has proven difficult. This lack of topoisomerase V in other archaeon has led researchers to believe that the origin of the enzyme in M. kandleri is a result of viral gene transfer and the unusual amount of orphan genes in the species provides evidence for this theory.[8] Additionally, the evolved cellular responses in M. kandleri due to its extreme environment has been another subject of research, as scientists look to apply the resilient enzymatic processes for industrial purposes.[5]

See also

References

  1. ↑ See the NCBI webpage on Methanopyrus. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. http://ftp.ncbi.nih.gov/pub/taxonomy/. 
  2. ↑ 2.0 2.1 2.2 "Cell proliferation at 122 degrees C and isotopically heavy CH4 production by a hyperthermophilic methanogen under high-pressure cultivation". Proceedings of the National Academy of Sciences of the United States of America 105 (31): 10949–54. August 2008. doi:10.1073/pnas.0712334105. PMID 18664583. Bibcode: 2008PNAS..10510949T. 
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 "The complete genome of hyperthermophile Methanopyrus kandleri AV19 and monophyly of archaeal methanogens". Proceedings of the National Academy of Sciences of the United States of America 99 (7): 4644–9. April 2002. doi:10.1073/pnas.032671499. PMID 11930014. Bibcode: 2002PNAS...99.4644S. 
  4. ↑ 4.0 4.1 "Search for the most 'primitive' membranes and their reinforcers: a review of the polyprenyl phosphates theory". Origins of Life and Evolution of the Biosphere 44 (3): 197–208. September 2014. doi:10.1007/s11084-014-9365-6. PMID 25351682. Bibcode: 2014OLEB...44..197N. 
  5. ↑ 5.0 5.1 5.2 5.3 Oren, Aharon (2014), Rosenberg, Eugene; DeLong, Edward F.; Lory, Stephen et al., eds., "The Family Methanopyraceae" (in en), The Prokaryotes (Berlin, Heidelberg: Springer Berlin Heidelberg): pp. 247–252, doi:10.1007/978-3-642-38954-2_328, ISBN 978-3-642-38953-5, http://link.springer.com/10.1007/978-3-642-38954-2_328, retrieved 2021-10-11 
  6. ↑ "InterPro". https://www.ebi.ac.uk/interpro/entry/InterPro/IPR016557/. 
  7. ↑ 7.0 7.1 "Salt dependence, kinetic properties and catalytic mechanism of N-formylmethanofuran:tetrahydromethanopterin formyltransferase from the extreme thermophile Methanopyrus kandleri". European Journal of Biochemistry 210 (3): 971–81. December 1992. doi:10.1111/j.1432-1033.1992.tb17502.x. PMID 1483480. 
  8. ↑ 8.0 8.1 8.2 Forterre, Patrick (June 2006). "DNA topoisomerase V: a new fold of mysterious origin" (in en). Trends in Biotechnology 24 (6): 245–247. doi:10.1016/j.tibtech.2006.04.006. PMID 16650908. https://linkinghub.elsevier.com/retrieve/pii/S016777990600103X. 
  9. ↑ Rajan, Rakhi; Osterman, Amy; Mondragón, Alfonso (2016-04-20). "Methanopyrus kandleri topoisomerase V contains three distinct AP lyase active sites in addition to the topoisomerase active site". Nucleic Acids Research 44 (7): 3464–3474. doi:10.1093/nar/gkw122. ISSN 0305-1048. PMID 26908655. PMC 4838376. https://doi.org/10.1093/nar/gkw122. 

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