title: Expression of a wheat cytochrome P450 monooxygenase in yeast and its inhibition by glyphosate.
abstract: Glyphosate is a non-selective herbicide which acts by inhibiting 5-enolpyruvylshikimate-3-phosphate synthase. Wheat cytochrome P450 monooxygenase specifically catalyzes the metabolism of some sulfonylurea herbicides such as chlorsulfuron and triasulfuron. Here we report that glyphosate is an inhibitor of a wheat cytochrome (CYP71C6v1), the cDNA of which was amplified by RT-PCR and heterologously expressed in yeast. The microsomal fractions derived from this strain had a Soret peak at 502 nm in the reduced carbon monoxide difference spectrum, which is a typical spectral characteristic. The addition of glyphosate to the microsomal protein resulted in a Type II spectrum indicative of binding via the nitrogen group to haem of cytochrome P450 as a sixth ligand. A spectral dissociation constant, K(s) of 70 micromol litre(-1) was observed and an IC50 of 11 micromol litre(-1) was found for glyphosate inhibition of CYP71C6v1 P450 activity.
authors.affiliation: State Key Laboratory for Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Science, Beijing 100080, China.
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: Xiang
authors.forename: Xiang-Jing
authors.initials: XJ
authors.lastname: Wang
authors.forename: Tian-Rui
authors.initials: TR
authors.lastname: Ren
authors.forename: Xiu-Lian
authors.initials: XL
authors.lastname: Ju
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006540:Herbicides / Q000494:pharmacology*; D008969:Molecular Sequence Data; D030781:Organisms, Genetically Modified; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014908:Triticum / Q000201:enzymology* / Q000235:genetics; D000097797:Glyphosate
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System; D005998:Glycine; D006540:Herbicides; D010940:Plant Proteins; D000097797:Glyphosate