Korarchaeum cryptofilum
Introduction
Candidatus Korarchaeum cryptofilum is a species of the proposed phylum Korarchaeota, or Xenarchaeota of the Archaea. The phylum is notoriously difficult to study given the environment in which it lives.[1] The Archean phylum is found mainly in hydrothermal environments such as hot springs, shallow water, and deep ocean. The organism's genome has mainly been studied to open understanding of Archaean evolution due to its distant detachment on the Archaea phyla.
Discovery
The phylum Korarchaeota was only recently discovered in 1996 by a team studying Archaea in hot springs located in Yellowstone National Park. By sequencing the ribosomal RNA of many uncultivated archaeans found in a hot spring, two outlying sequences were found. The two outlying sequences were used as evidence for the proposal of a new phylum "Korarchaeota".[2] The organisms of the Korarchaeota phylum are found mainly in extremophile environments such as hot springs(such as Candidatus Korarchaeum cryptofilum) while others live in hot biomes like deep ocean floors and icelandic volcanic vents.[3]
Genetics and Structure
Candidatus Korarchaeum cryptofilum is an ultrathin filamentous[2] heterotroph, mostly living through anaerobic metabolism of peptide fermentation and protein broken down into H2. The organism uses enzymes such as peptidase, transaminases, and ATPase. [1]
The genome of Ca. K. cryptofilum is a circular chromosome 1,590,757 base pairs long with an average G+C content of 49%. AUG is the start codon for 72.4% of the genome for understood protein-coidng genes, with UUG and GUG at 17.6% and 10% respectively. The arCOG of the archaean phyla crenarchaeota and euryarchaeota when compared with the sequenced genome of Ca. K. cryptofilum, showed that the organism shares its replication, recombination, repair, and cell division genes with that of crenarchaeota while it shares most of its transcription and translation genes with euryarcahaeota.
[4] The unusual similarity to Crenarchaeota and Euryarchaeota in the archaeons genome suggest its genome has "retained features that represent an ancestral archaeal form, existing before the occurence of the evolutionary bifurcation into Crenarchaeota and Euryarchaeota"[5].
Chromosome replication is provoked by two orc1/cdc6 homologous and one minichromosome maintenance protein complex. There are multiple DNA-dependent DNA polymerases. For transcription, Ca. K. cryptofilum has typical archaeal DNA-dependent RNA polymerase subunits.
The Archaeon has three rRNA genes (16S, 23S, and 5S rRNA). The organism has shown to produce 33 23S r-proteins and 27 16S r-proteins on its rRNA operon. The species is also found to have 45 tRNA genes on its genome with one initiator and 45 elongator tRNAs.[4][6]
The size of Candidatus Korarchaeum cryptofilum is 0.16-0.18μm in diameter with a varying length. [6].
Microbiome
The Microbiome of Candidatus Korarchaeum cryptofilum is extreme compared to humans. The archaeon is found in obsidian pools at the Yellowstone National Park in Wyoming, United States. The overall phylum population of theKorachaeota is generally minute in its microbiome (with Candidatus Korarchaeum cryptofilum even less of that) living in the biome. However in some cases they constitute 7% of all Archaea. The obsidian pools are very hot and high in saline concentration with only unicellular organisms living in it.[3]
Conclusion
Candidatus Korarchaeum cryptofilum is a relative unknown Archaeon microorganism of the minor phylum Korarchaeota. Little research has been performed on it but key insights on Archaean evolution has been discovered, causing Candidatus Korarchaeum cryptofilum to be used as a reference species. The microorganism has never bene successfully cultivated which is the reason for the Archaeon to be considered a "Candidatus" species. What is known about the species has come through 16S ribosomal RNA.[1]
References
- ↑ 1.0 1.1 1.2 Nealson, Ken. “A Korarchaeote yields to genome sequencing.” Proceedings of the National Academy of Sciences of the United States of America vol. 105,26 (2008): 8805-6. doi:10.1073/pnas.0804670105
- ↑ 2.0 2.1 Barns, S M et al. “Remarkable archaeal diversity detected in a Yellowstone National Park hot spring environment.” Proceedings of the National Academy of Sciences of the United States of America vol. 91,5 (1994): 1609-13. doi:10.1073/pnas.91.5.1609
- ↑ 3.0 3.1 Reigstad, Laila Johanne, et al. “Diversity and Abundance of Korarchaeota in Terrestrial Hot Springs of Iceland and Kamchatka.” ISME Journal: Multidisciplinary Journal of Microbial Ecology, vol. 4, no. 3, Mar. 2010, pp. 346–356. EBSCOhost, doi:10.1038/ismej.2009.126.
- ↑ 4.0 4.1 > Miller-Coleman, Robin L et al. “Korarchaeota diversity, biogeography, and abundance in Yellowstone and Great Basin hot springs and ecological niche modeling based on machine learning.” PloS one vol. 7,5 (2012): e35964. doi:10.1371/journal.pone.0035964
- ↑ Baltscheffsky, H. & Persson, B. J Mol Evol (2014) 78: 140
- ↑ 6.0 6.1 Elkins, James G et al. “A korarchaeal genome reveals insights into the evolution of the Archaea.” Proceedings of the National Academy of Sciences of the United States of America vol. 105,23 (2008): 8102-7. doi:10.1073/pnas.0801980105
Edited by [Charlie Stutz], student of Joan Slonczewski for BIOL 116 Information in Living Systems, 2019,
