The 22nd amino acid discovered to be directly encoded, pyrrolysine, is specified by UAG. Until recently, pyrrolysine was only known to be present in archaea from a methanogenic lineage (Methanosarcinales), where it is important in enzymes catalysing anoxic methylamines metabolism, and a few anaerobic bacteria. Relatively new discoveries have revealed wider presence in archaea, deepened functional understanding, shown remarkable carbon source-dependent expression of expanded decoding and extended exploitation of the pyrrolysine machinery for synthetic code expansion. At the same time, other studies have shown the presence of pyrrolysine-containing archaea in the human gut and this has prompted health considerations. The article reviews our knowledge of this fascinating exception to the ‘standard’ genetic code.
Skip Nav Destination
Article navigation
December 2018
-
Cover Image
Cover Image
In the cover image, which depicts archaeal cell division, fl uorescence microscopy shows FtsZ1-GFP localisation in pleomorphic cells of Haloferax volcanii. This archaeal model organism was originally isolated from the Dead Sea, but is well suited to live-cell studies owing to its relatively large, flat cells that show distinct differentiation. Multiple proteins from the tubulin superfamily control cell division and cell shape in this species (see article by Liao et al in this issue; pages 547–559). Archaea are expected to provide important insights into cellular evolution and fundamental cell structures such as the cytoskeleton. Image kindly provided by Iain Duggin (The ithree institute, University of Technology Sydney).
Review Article|
November 22 2018
Pyrrolysine in archaea: a 22nd amino acid encoded through a genetic code expansion
Emerg Top Life Sci (2018) 2 (4): 607–618.
Article history
Received:
July 18 2018
Revision Received:
September 24 2018
Accepted:
September 25 2018
 |
 |
