Methanosarcinaceae
Family of archaea
From Wikipedia, the free encyclopedia
Methanosarcinaceae is a family of archaeans in the order Methanosarcinales.[2]
| Methanosarcinaceae | |
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| Phase-contrast photo of Methanosarcina barkeri, type strain MST | |
Scientific classification  | |
| Domain: | Archaea |
| Kingdom: | Methanobacteriati |
| Phylum: | Methanobacteriota |
| Class: | "Methanomicrobia" |
| Order: | Methanosarcinales |
| Family: | Methanosarcinaceae Balch and Wolfe 1981[1] |
| Genera | |
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See text | |
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[1] and National Center for Biotechnology Information (NCBI).[2]
| 16S rRNA based LTP_10_2024[3][4][5] | 53 marker proteins based GTDB 10-RS226[6][7][8] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Unassigned gerea:
- Halomethanococcus Yu & Kawamura 1988
- "Ca. Methanovorans" Chadwick et al. 2022
Biochemistry
A notable trait of Methanosarcinaceae is that they are methanogens that incorporate the unusual amino acid pyrrolysine into their enzymes.[9] The enzyme monomethylamine methyltransferase catalyzes the reaction of monomethylamine to methane. This enzyme includes pyrrolysine. The unusual amino acid is inserted using a unique tRNA, the anticodon of which is UAG. In most organisms, and in most Methanosarcinaceae proteins, UAG is a stop codon. However in this enzyme, and anywhere else pyrrolysine is incorporated, likely through contextual markers on the mRNA, the pyrrolysine-loaded tRNA is inserted instead of the release factor. They also have a unique aminoacyl-tRNA synthetase to specifically load this tRNA with pyrrolysine. This unique adaptation is still the subject of significant study.