An anaerobic methanogen that lives at high temperatures and extreme pressures in geothermal marine sediments. This archaeon is a chemolithoautotroph (q.v.), and it gains its energy by the reaction 4H2 + CO2 → CH4 + 2H2O. Its chromosome is a circular DNA molecule made up of 1,644,976 base pairs that contain 1,682 ORFs. It also has two additional genetic elements. The larger is a circle made up of 58,407 bps that contain 44 ORFs, and the smaller circle is made up of 16,550 bps containing 12 ORFs. The genomes of M. jannaschii and H. influenzae are about the same size, yet they differ in the number of genes of unknown functions that they contain. The bacterium Haemophilus has 22% URFs, while the archaeon Methanoccus has 62% URFs. Methanococcal genes devoted to transcription, translation, and replication resemble those of eukaryotes more closely than bacteria. See Classification, Archea, Euryarchaeota; Chronology, 1996, Bult et al.;Archaebacteria, Archaeoglobus fulgidus, hyperthermophile.
Subjects: Genetics and Genomics.