Discovery:

• Krzycki and Chan were trying to figure out how the microbe Methanosarcina barkeri produces methane
• Pyrrolysine was observed in the structure of protein monomethylamine methyltransferase (MtmB) from this microbe, and was initially thought to be the amino acid lysine
• Further structural studies via mass spectrometry and crystallography revealed that it was a new amino acid, pyrrolysine

Production Method Discovered Later:

• Lysine was combined with another amino acid and enzymes in order to produce an intermediate product
• Mass spectrometry was used to observe this intermediate
  • A much different mass appeared than expected from the intermediate
• • A regular pyrrolysine molecule was seen rather than a structure made of two different amino acids
• Lysine is the only precursor, only three enzymes and two lysine molecules are necessary in the production process

Joseph A. Krzycki

• Department of Microbiology at The Ohio State University
• Professor, Departmental/Graduate Faculty
• Education
  • B.S. University of Nebraska, Lincoln
  • M.S. University of Wisconsin, Madison
  • Ph.D. University of Wisconsin, Madison
• Expert in biochemistry and molecular biology of methanogenic archaea

Michael Chan

• Former Chemist and Biochemist at The Ohio State University
• Professor, Departmental/Graduate Faculty
• Education
  • B.S., Chemistry, Harvey Mudd College
  • Ph.D., Chemistry, University of California, Berkeley
• Expert in molecular biophysics

Joseph Krzycki and Michael Chan were the leaders and faculty who with their research team discovered the 22nd amino acid, L-pyrrolysine, in 2002. The 22nd is only found in organisms which use methylamines as energy sources (methanogenic archaea and bacterium).

Chan and Bing Hao, a graduate student, identified a unique coding region within the MtmB gene that codes for methanogenic methylamine methyltranferases. These structures also carry a residue which, upon closer examination, was determined to be L-pyrrolysine.

Kryzycki along with Carey M. James and Gayathri Srinivasan, two other graduate students, found two other genes next to the MtmB gene. One of the genes encodes a special tRNA, and the other loads tRNA with lysine. Research suggests that  pyrrolysine is inserted into the MtmB gene during translation.

Quick Facts:

• 22^nd 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:

Pyrrolysine:

The discovery of L-pyrrolysine has changed the way methanogenic archaea and bacteria are studied. It has demonstrated an important role in the scientific study of amino acids, and is proof that there are many more paths that require scientific exploration.

• The discovery of L-pyrrolysine has been an important piece of evidence in the evolution of the genetic code
• Establishing a mechanism for the formation of L-pyrrolysine can prove useful the discovery of additional essential building blocks