Discovery of tauroursodeoxycholic acid biotransformation enzymes from the gut microbiome of black bears using metagenomics

Sci Rep. 2017 Apr 24;7:45495. doi: 10.1038/srep45495.


Tauroursodeoxycholic acid (TUDCA) has been used to treat many diseases effectively. 7α-hydroxysteroid dehydrogenase (7α-HSDH) and 7β-hydroxysteroid dehydrogenase (7β-HSDH) are two key enzymes that drive the efficient biosynthesis of TUDCA from taurochenodeoxycholic acid (TCDCA) in vitro. In this study, a metagenomic approach was used to isolate 7α- and 7β-HSDHs from fecal samples of black bears. Five new 7α-HSDHs and one new 7β-HSDH enzyme were discovered and identified from the gut microbiota of black bears, and four of them presented good enzymatic properties. Our data also suggest cooperation in the biotransformation of TUDCA by the gut microbiota in black bears. In conclusion, this work expands the natural enzyme bank of HSDHs, provides promising candidate enzymes for application in the biosynthesis TUDCA and the epimerization reaction of bile acids at the C-7 position, and provides a data set for the discovery of novel enzymes in the gut micriobiome of black bears.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacteria / enzymology
  • Bacteria / isolation & purification
  • Bile Acids and Salts / chemistry
  • Bile Acids and Salts / metabolism
  • Cloning, Molecular
  • DNA, Bacterial / isolation & purification
  • DNA, Bacterial / metabolism
  • Feces / microbiology
  • Gastrointestinal Microbiome*
  • Hydroxysteroid Dehydrogenases / chemistry
  • Hydroxysteroid Dehydrogenases / genetics
  • Hydroxysteroid Dehydrogenases / metabolism*
  • Kinetics
  • Metagenomics*
  • Protein Stability
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / isolation & purification
  • Sequence Alignment
  • Stereoisomerism
  • Taurochenodeoxycholic Acid / metabolism*
  • Ursidae


  • Bile Acids and Salts
  • DNA, Bacterial
  • Recombinant Proteins
  • Taurochenodeoxycholic Acid
  • ursodoxicoltaurine
  • Hydroxysteroid Dehydrogenases
  • 7 beta-hydroxysteroid dehydrogenase
  • 7 alpha-hydroxysteroid dehydrogenase