Structural highlights
Publication Abstract from PubMed[FeFe] hydrogenases interconvert H2 into protons and electrons reversibly and efficiently. The active site H-cluster is composed of two sites: a unique [2Fe] sub-cluster ([2Fe]H) covalently linked via cysteine to a canonical [4Fe-4S] cluster ([4Fe-4S]H). Both sites are redox active and its electron transfer is proton-coupled, such that the potential of the H-cluster lies very close to the H2 thermodynamic potential, which confers the enzyme with the ability to operate quickly in both directions without energy losses. Here, one of the cysteines coordinating [4Fe-4S]H (Cys362) in the [FeFe] hydrogenase from the green alga Chlamydomonas reinhardtii ( CrHydA1) was exchanged with histidine and the resulting C362H variant was shown to contain a [4Fe-4S] cluster with a more positive redox potential than the wild-type. The change in the [4Fe-4S] cluster potential resulted in a shift of the catalytic bias, diminishing the H2 production activity but giving significant higher H2 oxidation activity, albeit with a 200 mV overpotential requirement. These results highlight the importance of the [4Fe-4S] cluster as an electron injection site, modulating the redox potential and the catalytic properties of the H-cluster. His-ligation to the [4Fe-4S] sub-cluster tunes the catalytic bias of [FeFe] hydrogenase.,Rodriguez-Macia P, Kertess L, Burnik J, Birrell JA, Hofmann E, Lubitz W, Happe T, Rudiger O J Am Chem Soc. 2018 Dec 14. doi: 10.1021/jacs.8b11149. PMID:30545220[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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