Archaea

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Archaea

Evolutionary biology
One of the three domains of living organisms: Archaea, Bacteria and Eukaryota. While Archaea are single-celled, they are unlike bacteria given their independent evolutionary history. Archaea differ from Eukaryota in their ribosomal structure and the presence—in some—of introns in the genome, as well as other features (e.g., different membrane composition).
 
Molecular biology
Archaea are of interest in biotechnology as they have unique biochemical features (e.g., enzymes of theromophiles, such as Taq polymerase, the “workhorse” enzyme of PCR) and are extremely stable at high temperatures. Archaea include metabolic oddities (e.g., extreme halophiles, which live in extremely salty environments), methanogens (which produce methane) and sulphur-dependant extreme thermophiles (which can live in extremely hot environments).

Archaea phyla
• Crenarchaeota
• Euryarchaeota
• Korarchaeota
• Nanoarchaeota
• Thaumarchaeota (recently proposed)

Archaea

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References in periodicals archive ?
Structural Relationship between the Eukaryotic B-Block Binding Subunit and Archaeal Protein. As described above, archaeal B-block binding subunits are approximately 100-200 aa in length, while eukaryotic subunits are more than 1000 aa in length.
Interestingly, one of the characteristics of many archaeal proteins led to visual support that these "simpler" organisms may be more related to eukarya at certain levels than their bacterial counterparts.
With an even greater lack of sequence similarity between the bacterial protein with the eukaryotic and archaeal proteins, coupled with stark differences in protein length, it was likely a surprise to some researchers that the bacterial [micro]-clamp shares the overall PCNA ring-shape, including the 12 helix/6 sheet organization [57, 58].
As systems that inform responses to extreme environmental stress, the archaeal proteins provide biological insights along with precise structural knowledge of complexes and conformations that are often prototypical and foundational.