Structure of the non-redox-active tungsten/[4Fe:4S] enzyme acetylene hydratase.
The tungsten-iron-sulfur enzyme acetylene hydratase stands out from its class because it catalyzes a nonredox reaction, the hydration of acetylene to acetaldehyde. Sequence comparisons group the protein into the dimethyl sulfoxide reductase family, and it contains a bis-molybdopterin guanine dinucleotide-ligated tungsten atom and a cubane-type [4Fe:4S] cluster. The crystal structure of acetylene hydratase at 1.26 A now shows that the tungsten center binds a water molecule that is activated by an adjacent aspartate residue, enabling it to attack acetylene bound in a distinct, hydrophobic pocket. This mechanism requires a strong shift of pK(a) of the aspartate, caused by a nearby low-potential [4Fe:4S] cluster. To access this previously unrecognized W-Asp active site, the protein evolved a new substrate channel distant from where it is found in other molybdenum and tungsten enzymes.
Seiffert
Grazyna B
GB
Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany.
Ullmann
G Matthias
GM
Messerschmidt
Albrecht
A
Schink
Bernhard
B
Kroneck
Peter M H
PM
Einsle
Oliver
O
D001665:Binding Sites / Q000235:genetics; D003460:Crystallization; D020564:Deltaproteobacteria / Q000737:chemistry*; D006836:Hydro-Lyases / Q000737:chemistry*; D008958:Models, Molecular; D055672:Static Electricity; D014414:Tungsten / Q000737:chemistry
D006836:Hydro-Lyases; C096200:acetylene hydratase; D014414:Tungsten