Dual diaminopimelate biosynthesis pathways in Bacteroides fragilis and Clostridium thermocellum

Biochim Biophys Acta. 2011 Sep;1814(9):1162-8. doi: 10.1016/j.bbapap.2011.04.019. Epub 2011 May 14.


Bacteroides fragilis and Clostridium thermocellum were recently found to synthesize diaminopimelate (DAP) by way of LL-DAP aminotransferase. Both species also contain an ortholog of meso-diaminopimelate dehydrogenase (Ddh), suggesting that they may have redundant pathways for DAP biosynthesis. The B. fragilis Ddh ortholog shows low homology with other examples of Ddh and this species belongs to a phylum, the Bacteriodetes, not previously known to contain this enzyme. By contrast, the C. thermocellum ortholog is well conserved with known examples of Ddh. Using in vitro and in vivo assays both the B. fragilis and C. thermocellum enzymes were found to be authentic examples of Ddh, displaying kinetic properties typical of this enzyme. The result indicates that B. fragilis contains a sequence diverged form of Ddh. Phylogenomic analysis of the microbial genome database revealed that 77% of species with a Ddh ortholog also contain a second pathway for DAP biosynthesis suggesting that Ddh evolved as an ancillary mechanism for DAP biosynthesis.

Publication types

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

MeSH terms

  • Amino Acid Oxidoreductases / chemistry
  • Amino Acid Oxidoreductases / physiology*
  • Amino Acid Sequence
  • Bacteroides fragilis / metabolism*
  • Clostridium thermocellum / metabolism*
  • Diaminopimelic Acid / metabolism*
  • Evolution, Molecular
  • Molecular Sequence Data
  • Phylogeny


  • Diaminopimelic Acid
  • Amino Acid Oxidoreductases
  • diaminopimelate dehydrogenase