H2O2-dependent substrate oxidation by an engineered diiron site in a bacterial hemerythrin

Yasunori Okamoto,Akira Onoda,Donald M Kurtz,Yoshitsugu Shiro,Shun Hirota,Yu Takano,Takashi Hayashi,Hiroshi Sugimoto

doi:10.1039/c3cc48108e

Abstract

The O2-binding carboxylate-bridged diiron site in DcrH-Hr was engineered in an effort to perform the H2O2-dependent oxidation of external substrates. A His residue was introduced near the diiron site in place of a conserved residue, Ile119. The I119H variant promotes the oxidation of guaiacol and 1,4-cyclohexadiene upon addition of H2O2.

Highlights

O2 is utilized in several non-heme diiron-carboxylate proteins performing essential biological processes ranging from transport of O2,[1,2] hydroxylation of C–H bonds,[3] generation of a tyrosyl radical for DNA synthesis,[4] and reduction of unsaturated fatty acids (D9 desaturase).[5]
The exogenous ligand binding properties of the met-I119H diiron site were investigated using azide, which is known to coordinate to Fe2 in place of chloride in met form of wild type DcrH-Hr (WT) (met-WT).[9]
We evaluated the reactivity of I119H toward H2O2 as a potential exogenous ligand, which, like azide, could form a hydrogen bond with the pendant H119 residue

Summary

Introduction

O2 is utilized in several non-heme diiron-carboxylate proteins performing essential biological processes ranging from transport of O2 (hemerythrin, Hr),[1,2] hydroxylation of C–H bonds (methane monooxygenase hydroxylase),[3] generation of a tyrosyl radical for DNA synthesis (ribonucleotide reductase),[4] and reduction of unsaturated fatty acids (D9 desaturase).[5]. The O2-binding carboxylate-bridged diiron site in DcrH-Hr was engineered in an effort to perform the H2O2-dependent oxidation of external substrates.

Results

Conclusion