Cytochrome P450 CYP710A encodes the sterol C-22 desaturase in Arabidopsis and tomato

Plant Cell. 2006 Apr;18(4):1008-22. doi: 10.1105/tpc.105.036012. Epub 2006 Mar 10.

Abstract

Delta22-unsaturated sterols, containing a double bond at the C-22 position in the side chain, occur specifically in fungi and plants. Here, we describe the identification and characterization of cytochrome P450s belonging to the CYP710A family as the plant C-22 desaturase. Recombinant proteins of CYP710A1 and CYP710A2 from Arabidopsis thaliana and CYP710A11 from tomato (Lycopersicon esculentum) were expressed using a baculovirus/insect system. The Arabidopsis CYP710A1 and tomato CYP710A11 proteins exhibited C-22 desaturase activity with beta-sitosterol to produce stigmasterol (CYP710A1, K(m) = 1.0 microM and kinetic constant [k(cat)] = 0.53 min(-1); CYP710A11, K(m) = 3.7 microM and k(cat) = 10 min(-1)). In Arabidopsis transgenic lines with CYP710A1 and CYP710A11 overexpression, stigmasterol levels increased by 6- to 32-fold. Arabidopsis CYP710A2 was able to produce brassicasterol and stigmasterol from 24-epi-campesterol and beta-sitosterol, respectively. Sterol profiling analyses for CYP710A2 overexpression and a T-DNA insertion event into CYP710A2 clearly demonstrated in planta that CYP710A2 was responsible for both brassicasterol and stigmasterol production. Semiquantitative PCR analyses and promoter:beta-glucuronidase transgenic approaches indicated strict tissue/organ-specific regulation for each CYP710A gene, implicating differential tissue distributions of the Delta(22)-unsaturated sterols in Arabidopsis. Our results support the possibility that the CYP710 family may encode P450s of sterol C-22 desaturases in different organisms.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics
  • Conserved Sequence
  • Cytochrome P-450 Enzyme System / genetics*
  • Kinetics
  • Lycopersicon esculentum / enzymology*
  • Lycopersicon esculentum / genetics
  • Molecular Sequence Data
  • Oxidoreductases / genetics
  • Plant Proteins / genetics*
  • Plants, Genetically Modified
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Sitosterols / metabolism
  • Sterols / biosynthesis
  • Stigmasterol / metabolism

Substances

  • Arabidopsis Proteins
  • Plant Proteins
  • Sitosterols
  • Sterols
  • gamma-sitosterol
  • Cytochrome P-450 Enzyme System
  • Stigmasterol
  • Oxidoreductases

Associated data

  • GENBANK/AAB68433
  • GENBANK/AB219423
  • GENBANK/AB223043
  • GENBANK/AB233425
  • GENBANK/AW622568
  • GENBANK/CAA89116
  • GENBANK/CAB11640
  • GENBANK/EAA32679
  • GENBANK/EAA59021
  • GENBANK/EAK81168
  • GENBANK/EAK98020
  • GENBANK/EAL88107
  • GENBANK/TC101450
  • RefSeq/NM_188395
  • RefSeq/NP_172633
  • RefSeq/NP_215278