Title

Maug, A Diheme Enzyme That Catalyzes Tryptophan Tryptophylquinone Biosynthesis By Remote Catalysis

Keywords

Electron transfer; High-valence iron; Oxygenase; Peroxidase; Posttranslational modification; Protein radical

Abstract

MauG contains two c-type hemes with atypical physical and catalytic properties. While most c-type cytochromes function simply as electron transfer mediators, MauG catalyzes the completion of tryptophan tryptophylquinone (TTQ)1 biosynthesis within a precursor protein of methylamine dehydrogenase. This posttranslational modification is a six-electron oxidation that requires crosslinking of two Trp residues, oxygenation of a Trp residue and oxidation of the resulting quinol to TTQ. These reactions proceed via a bis-FeIV state in which one heme is present as FeIVO and the other is FeIV with axial heme ligands provided by His and Tyr side chains. Catalysis does not involve direct contact between the protein substrate and either heme of MauG. Instead it is accomplished by remote catalysis using a hole hopping mechanism of electron transfer in which Trp residues of MauG are reversibly oxidized. In this process, long range electron transfer is coupled to the radical mediated chemical reactions that are required for TTQ biosynthesis. © 2013 Elsevier Inc. All rights reserved.

Publication Date

2-15-2014

Publication Title

Archives of Biochemistry and Biophysics

Volume

544

Number of Pages

112-118

Document Type

Review

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.abb.2013.10.004

Socpus ID

84893718032 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84893718032

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