Rice cytochrome P450 MAX1 homologs catalyze distinct steps in strigolactone biosynthesis

Nat Chem Biol. 2014 Dec;10(12):1028-33. doi: 10.1038/nchembio.1660. Epub 2014 Oct 26.


Strigolactones (SLs) are a class of phytohormones and rhizosphere signaling compounds with high structural diversity. Three enzymes, carotenoid isomerase DWARF27 and carotenoid cleavage dioxygenases CCD7 and CCD8, were previously shown to convert all-trans-β-carotene to carlactone (CL), the SL precursor. However, how CL is metabolized to SLs has remained elusive. Here, by reconstituting the SL biosynthetic pathway in Nicotiana benthamiana, we show that a rice homolog of Arabidopsis More Axillary Growth 1 (MAX1), encodes a cytochrome P450 CYP711 subfamily member that acts as a CL oxidase to stereoselectively convert CL into ent-2'-epi-5-deoxystrigol (B-C lactone ring formation), the presumed precursor of rice SLs. A protein encoded by a second rice MAX1 homolog then catalyzes the conversion of ent-2'-epi-5-deoxystrigol to orobanchol. We therefore report that two members of CYP711 enzymes can catalyze two distinct steps in SL biosynthesis, identifying the first enzymes involved in B-C ring closure and a subsequent structural diversification step of SLs.

MeSH terms

  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Biocatalysis
  • Dioxygenases / genetics
  • Dioxygenases / metabolism*
  • Gene Expression Regulation, Plant*
  • Lactones / metabolism
  • Metabolic Networks and Pathways
  • Models, Molecular
  • Molecular Docking Simulation
  • Oryza / enzymology*
  • Oryza / genetics
  • Plant Growth Regulators / biosynthesis*
  • Plants, Genetically Modified
  • Sequence Homology, Amino Acid
  • Tobacco / enzymology
  • Tobacco / genetics
  • beta Carotene / metabolism


  • 5-deoxystrigol
  • Arabidopsis Proteins
  • D27 protein, Arabidopsis
  • Lactones
  • MAX1 protein, Arabidopsis
  • Plant Growth Regulators
  • carlactone
  • orobanchol
  • beta Carotene
  • CCD7 protein, Arabidopsis
  • CCD8 protein, Arabidopsis
  • Dioxygenases