title: Structure and Function of the Unusual Tungsten Enzymes Acetylene Hydratase and Class II Benzoyl-Coenzyme A Reductase.
abstract: 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.
authors.affiliation: Fakultx00E4;t fx00FC;r Biologie/Mikrobiologie, Institut fx00FC;r Biochemie, Albert-Ludwigs-Universitx00E4;t Freiburg, Freiburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Boll
authors.forename: Oliver
authors.initials: O
authors.lastname: Einsle
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ermler
authors.forename: Peter M H
authors.initials: PM
authors.lastname: Kroneck
authors.forename: G Matthias
authors.initials: GM
authors.lastname: Ullmann
mesh_terms: D001421:Bacteria, Anaerobic / Q000201:enzymology / Q000378:metabolism; D020134:Catalytic Domain; D003067:Coenzymes / Q000737:chemistry / Q000378:metabolism; D039301:Computers, Molecular; D006836:Hydro-Lyases / Q000737:chemistry* / Q000378:metabolism*; D006841:Hydrocarbons, Aromatic / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry* / Q000378:metabolism*; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011622:Pterins / Q000378:metabolism; D014414:Tungsten / Q000378:metabolism*
chemical_list: D003067:Coenzymes; D006841:Hydrocarbons, Aromatic; D011622:Pterins; C490076:pyranopterin; D044925:Oxidoreductases Acting on CH-CH Group Donors; C109030:benzoyl-coenzyme A reductase (dearomatizing); D006836:Hydro-Lyases; C096200:acetylene hydratase; D014414:Tungsten