Identification of a 5'-deoxyadenosine deaminase in Methanocaldococcus jannaschii and its possible role in recycling the radical S-adenosylmethionine enzyme reaction product 5'-deoxyadenosine

J Bacteriol. 2014 Mar;196(5):1064-72. doi: 10.1128/JB.01308-13. Epub 2013 Dec 27.


We characterize here the MJ1541 gene product from Methanocaldococcus jannaschii, an enzyme that was annotated as a 5'-methylthioadenosine/S-adenosylhomocysteine deaminase (EC The MJ1541 gene product catalyzes the conversion of 5'-deoxyadenosine to 5'-deoxyinosine as its major product but will also deaminate 5'-methylthioadenosine, S-adenosylhomocysteine, and adenosine to a small extent. On the basis of these findings, we are naming this new enzyme 5'-deoxyadenosine deaminase (DadD). The Km for 5'-deoxyadenosine was found to be 14.0 ± 1.2 μM with a kcat/Km of 9.1 × 10(9) M(-1) s(-1). Radical S-adenosylmethionine (SAM) enzymes account for nearly 2% of the M. jannaschii genome, where the major SAM derived products is 5'-deoxyadenosine. Since 5'-dA has been demonstrated to be an inhibitor of radical SAM enzymes; a pathway for removing this product must be present. We propose here that DadD is involved in the recycling of 5'-deoxyadenosine, whereupon the 5'-deoxyribose moiety of 5'-deoxyinosine is further metabolized to deoxyhexoses used for the biosynthesis of aromatic amino acids in methanogens.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Archaeal Proteins / genetics
  • Archaeal Proteins / metabolism*
  • Cloning, Molecular
  • Deoxyadenosines / chemistry
  • Deoxyadenosines / genetics
  • Deoxyadenosines / metabolism*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression Regulation, Archaeal / physiology
  • Gene Expression Regulation, Enzymologic / physiology
  • Methanocaldococcus / enzymology*
  • Methanocaldococcus / genetics
  • Methanocaldococcus / metabolism
  • Molecular Structure
  • Mutation
  • Nucleotide Deaminases / genetics
  • Nucleotide Deaminases / metabolism*
  • Protein Stability
  • S-Adenosylmethionine / chemistry
  • S-Adenosylmethionine / metabolism


  • Archaeal Proteins
  • Deoxyadenosines
  • 5'-deoxyadenosine
  • S-Adenosylmethionine
  • Nucleotide Deaminases