The 22nd Amino Acid: Pyrrolysine

Quick Facts:

  • 22nd genetically encoded amino acid
  • α-amino acid not present in humans
  • Abundant in methanogenic archaea and bacterium
    • Anaerobic microorganisms
    • Reduce carbon dioxide and hydrogen gas to methane
    • Relevant in energy conservation
  • Works to bind, activate, and orient methylamines during protein synthesis
  • Present in the last universal common ancestor (3 billion years ago)
    • Only persisted in organisms that use methyalmines as energy sources

Synthesis:

  • Synthesized from two molecules of L-lysine
  • Encoded by mRNA in the UAG region
    • Normally an “amber” stop codon

Lysine:

L-lysine

Pyrrolysine:

240px-Pyrrolysine.svg