Kurr et al. 1992
Methanopyrus is a genus of methanogen, with a single described species, M. kandleri. It is a hyperthermophile, discovered on the wall of a black smoker from the Gulf of California at a depth of 2000 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. 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.
Methanopyrus kandleri is different from other archaea because it still has one of the simplest versions of membrane lipids. The membrane of M. kandleri is made of terpenoid lipids, which is a group of lipids containing cholesterol, hopanoids, carotenoid, phytane, and bisphytane. Although terpenoids are the main component of the membrane in M. kandleri, they are more of a supporting structure in eukaryote and bacteria.
Methanopyrus kandleri has a high concentration of cyclic 2,3-diphosphoglycerate. This compound is often found in hyperthermophile, helping to prevent protein denaturation in high temperatures. 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. This increased concentration of salt helps with enzyme stability and promotes activity of the enzymes at higher temperatures.
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. Overall, the genome of M. kandleri is considered ‘minimalist’ because so few genes have been transferred from other organisms into its own genome. This could be due to the extreme environment that it lives in and the low number of potential transfers it could have because of it.
Methanopyrus kandleri is also the only species known to have topoisomerase 5. Topoisomerase 5 allows for M. kandleri to survive in such high temperatures and helps to relax both positively and negatively supercoiled DNA . Although topoisomerase 5 is useful in this case, finding other hyperthermophiles that have topoisomerase 5 has proven difficult. Because of this, more research is being done to fully understand how M. kandleri obtained topoisomerase 5, and why no other hyperthermophiles have it.
- See the NCBI webpage on Methanopyrus. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. Retrieved 2007-03-19.
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