Discovery of acetylene hydratase activityof the iron–sulphur protein IspH

摘要

The final step of the methylerythritol phosphate isoprenoid biosynthesis pathway iscatalysed by the iron–sulphur enzyme IspH, producing the universal precursors of terpenes:isopentenyl diphosphate and dimethylallyl diphosphate. Here we report an unforeseen reactiondiscovered during the investigation of the interaction of IspH with acetylene inhibitors byX-ray crystallography, mossbauer, and nuclear magnetic resonance spectroscopy. In additionto its role as a 2H+/2e- reductase, IspH can hydrate acetylenes to aldehydes and ketones viaanti-markovnikov/markovnikov addition. The reactions only occur with the oxidised proteinand proceed via ita 1-o-enolate intermediates. one of these is characterized crystallographicallyand contains a C4 ligand oxygen bound to the unique, fourth iron in the 4Fe-4s cluster: thisintermediate subsequently hydrolyzes to produce an aldehyde product. This unexpected sideto IspH reactivity is of interest in the context of the mechanism of action of other acetylenehydratases, as well as in the design of antiinfectives targeting IspH.