Cenarchaeum

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A Microbial Biorealm page on the genus Cenarchaeum

Classification

Domain: Archaea; Phylum: Thaumarchaeota; Order: Cenarchaeales; Family: Cenarchaeaceae; Genus: Cenarchaeum

An important species is Cenarchaeum symbiosum.

Description and significance

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Genome structure

Cenarchaeum symbiosum has a single circular chromosome 2,045,086 bp in length. On average, the genome has 57.74% G/C content. The origin(s) of replication are not known. 2,017 protein-encoding genes were predicted and for 65% of these, homology searches showed functional or conserved roles.


In terms of metabolism, genetic analysis suggests that C. symbiosum uses at least an incomplete TCA cycle. The genome also indicates an intact Embden-Meyerhof-Parnas pathway, although without glucokinase or pyruvate kinase, which suggests that it may form glucose through this pathway rather than breaking it down. However, genes were also found to encode carbohydrate kinases of unknown specificity. Many Entner-Douodoroff pathway components were missing from the genome, indicating that this archaeum does not use the ED pathway for catabolism. However, a nonoxidative pentose phosphate pathway was identified, which could provide NADPH and ribose sugars for anabolism. Homologous genes that could be associated with ammonia oxidation occur in the genome of C. symbiosum, but between missing homologues and identified potential cytochrome replacements for mobile electron carrying suggest that energy derived from ammonia oxidiation is obtained through different mechanisms than those of most nitrifying bacteria.


This genome contains most of the core genes generally expected of Archaea. A eukaryal-like H3-H4 histone was also found in the genome of C. symbiosum, the first crenarchaeote in which this was found.

Cell structure, metabolism & life cycle

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Ecology (including pathogenesis)

Describe its habitat, symbiosis, and contributions to environment. If it is a pathogen, how does this organism cause disease? Human, animal, plant hosts? Describe virulence factors and patient symptoms.

Interesting feature

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References

Euzeby, J.P. "Classification of domains and phyla - Hierarchical classification of prokaryotes (bacteria)". List of Prokaryotic names with Standing in Nomenclature. Last major update October 06, 2011. Accessed October 19, 2011.

Hallam, S.J., K.T. Konstantinidis, N. Putnam, C. Schleper, Y. Watanabe, J. Sugahara, C. Preston,J. de la Torre, P.M. Richardson, and E.F. DeLong. "Genomic analysis of the uncultivated marine crenarchaeote Cenarchaeum symbiosum". Proceedings of the National Academy of Sciences of the United States of America. 2006. Volume 103. p. 18296-18301.

Preston, C.M., K.Y. Wu, T.F. Molinski, and E.F. DeLong. "A psychrophilic crenarchaeon inhabits a marine sponge: Cenarchaeum symbiosum gen. nov., sp. nov.". Proceedings of the National Academy of Sciences of the United States of America. 1996. Volume 93. p. 6241-6246