Structure and Function of the Unusual Tungsten Enzymes Acetylene Hydratase and Class II Benzoyl-Coenzyme A Reductase

• Published in: Journal of molecular microbiology and biotechnology Vol. 26; no. 1-3; p. 119
• Main Authors: Boll, Matthias, Einsle, Oliver, Ermler, Ulrich, Kroneck, Peter M H, Ullmann, G Matthias
• Format: Journal Article
• Language: English
• Published: Switzerland 01.01.2016
• Subjects: Bacteria, Anaerobic - enzymology; Bacteria, Anaerobic - metabolism; Catalytic Domain; Coenzymes - chemistry; Coenzymes - metabolism; Computers, Molecular; Hydro-Lyases - chemistry; Hydro-Lyases - metabolism; Hydrocarbons, Aromatic - metabolism; Models, Molecular; Oxidation-Reduction; Oxidoreductases Acting on CH-CH Group Donors - chemistry; Oxidoreductases Acting on CH-CH Group Donors - metabolism; Phylogeny; Protein Structure, Tertiary; Pterins - metabolism; Tungsten - metabolism
• ISSN: 1660-2412
• DOI: 10.1159/000440805

In biology, tungsten (W) is exclusively found in microbial enzymes bound to a bis-pyranopterin cofactor (bis-WPT). Previously known W enzymes catalyze redox oxo/hydroxyl transfer reactions by directly coordinating their substrates or products to the metal. They comprise the W-containing formate/formylmethanofuran dehydrogenases belonging to the dimethyl sulfoxide reductase (DMSOR) family and the aldehyde:ferredoxin oxidoreductase (AOR) families, which form a separate enzyme family within the Mo/W enzymes. In the last decade, initial insights into the structure and function of two unprecedented W enzymes were obtained: the acetaldehyde forming acetylene hydratase (ACH) belongs to the DMSOR and the class II benzoyl-coenzyme A (CoA) reductase (BCR) to the AOR family. The latter catalyzes the reductive dearomatization of benzoyl-CoA to a cyclic diene. Both are key enzymes in the degradation of acetylene (ACH) or aromatic compounds (BCR) in strictly anaerobic bacteria. They are unusual in either catalyzing a nonredox reaction (ACH) or a redox reaction without coordinating the substrate or product to the metal (BCR). In organic chemical synthesis, analogous reactions require totally nonphysiological conditions depending on Hg2+ (acetylene hydration) or alkali metals (benzene ring reduction). The structural insights obtained pave the way for biological or biomimetic approaches to basic reactions in organic chemistry.