Directed evolution of squalene synthase for dehydrosqualene biosynthesis

FEBS Lett. 2014 Sep 17;588(18):3375-81. doi: 10.1016/j.febslet.2014.07.028. Epub 2014 Aug 2.


Squalene synthase (SQS) catalyzes the first step of sterol/hopanoid biosynthesis in various organisms. It has been long recognized that SQSs share a common ancestor with carotenoid synthases, but it is not known how these enzymes selectively produce their own product. In this study, SQSs from yeast, human, and bacteria were independently subjected to directed evolution for the production of the C30 carotenoid backbone, dehydrosqualene. This was accomplished via high-throughput screening with Pantoea ananatis phytoene desaturase, which can selectively convert dehydrosqualene into yellow carotenoid pigments. Genetic analysis of the resultant mutants revealed various mutations that could effectively convert SQS into a "dehydrosqualene synthase." All of these mutations are clustered around the residues that have been proposed to be important for NADPH binding.

Keywords: Carotenoid synthase; Directed evolution; Phytoene desaturase; Squalene synthase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics*
  • Biocatalysis
  • Directed Molecular Evolution
  • Farnesyl-Diphosphate Farnesyltransferase / chemistry
  • Farnesyl-Diphosphate Farnesyltransferase / genetics*
  • Humans
  • Models, Molecular
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics*
  • Squalene / analogs & derivatives*
  • Squalene / chemical synthesis


  • Bacterial Proteins
  • Saccharomyces cerevisiae Proteins
  • dehydrosqualene
  • Squalene
  • Farnesyl-Diphosphate Farnesyltransferase