Selenocysteine as a Substrate, an Inhibitor and a Mechanistic Probe for Bacterial and Fungal Iron‐Dependent Sulfoxide Synthases. Issue 6 (20th January 2020)

• Record Type: Journal Article
• Authors: Goncharenko, Kristina V.; Flückiger, Sebastian; Liao, Cangsong; Lim, David; Stampfli, Anja R.; Seebeck, Florian P.
• Is Part Of: Chemistry. Volume 26:Issue 6(2020)
• Page Start: 1328
• Page End: 1334
• Publication Date: 2020-01-20
• Subjects: antioxidants -- enzyme catalysis -- ergothioneine -- natural products -- selenoneine; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201903898
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Sulfoxide synthases are non‐heme iron enzymes that participate in the biosynthesis of thiohistidines, such as ergothioneine and ovothiol A. The sulfoxide synthase EgtB from Chloracidobacterium thermophilum ( Cth EgtB) catalyzes oxidative coupling between the side chains of N ‐α‐trimethyl histidine (TMH) and cysteine (Cys) in a reaction that entails complete reduction of molecular oxygen, carbon–sulfur (C−S) and sulfur–oxygen (S−O) bond formation as well as carbon–hydrogen (C−H) bond cleavage. In this report, we show that Cth EgtB and other bacterial sulfoxide synthases cannot efficiently accept selenocysteine (SeCys) as a substrate in place of cysteine. In contrast, the sulfoxide synthase from the filamentous fungus Chaetomium thermophilum ( Cth Egt1) catalyzes C−S and C−Se bond formation at almost equal efficiency. We discuss evidence suggesting that this functional difference between bacterial and fungal sulfoxide synthases emerges from different modes of oxygen activation. Abstract : Sulfoxide synthases : Bacterial and fungal iron‐dependent sulfoxide synthases are distinguished by their different abilities to catalyze oxidative carbon–selenium bond formation.