Expression of a wheat cytochrome P450 monooxygenase in yeast and its inhibition by glyphosate

✍ Scribed by Wen-Sheng Xiang; Xiang-Jing Wang; Tian-Rui Ren; Xiu-Lian Ju

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 110 KB
• Volume: 61
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/ps.969

✦ Synopsis

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 µmol litre^−1^ was observed and an IC~50~ of 11 µmol litre^−1^ was found for glyphosate inhibition of CYP71C6v1 P450 activity. Copyright © 2005 Society of Chemical Industry