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Structure-function relationships in [FeFe]-hydrogenase active site maturation.

ABSTRACT: Since the discovery that, despite the active site complexity, only three gene products suffice to obtain active recombinant [FeFe]-hydrogenase, significant light has been shed on this process. Both the source of the CO and CN(-) ligands to iron and the assembly site of the catalytic subcluster are known, and an apo structure of HydF has been published recently. However, the nature of the substrate(s) for the synthesis of the bridging dithiolate ligand to the subcluster remains to be established. From both spectroscopy and model chemistry, it is predicted that an amine function in this ligand plays a central role in catalysis, acting as a base in the heterolytic cleavage of hydrogen.

SUBMITTER: Nicolet Y

PROVIDER: S-EPMC3340144 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Structure-function relationships in [FeFe]-hydrogenase active site maturation.

Nicolet Yvain Y Fontecilla-Camps Juan C JC

The Journal of biological chemistry 20120302 17

Since the discovery that, despite the active site complexity, only three gene products suffice to obtain active recombinant [FeFe]-hydrogenase, significant light has been shed on this process. Both the source of the CO and CN(-) ligands to iron and the assembly site of the catalytic subcluster are known, and an apo structure of HydF has been published recently. However, the nature of the substrate(s) for the synthesis of the bridging dithiolate ligand to the subcluster remains to be established. ...[more]

PMID: 22389497

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Project description:[FeFe]-Hydrogenases catalyze the evolution and oxidation of hydrogen using a characteristic cofactor, termed the H-cluster. This comprises an all cysteine coordinated [4Fe-4S] cluster and a unique [2Fe] moiety, coupled together via a single cysteine. The coordination of the [4Fe-4S] cluster in HydA1 from Chlamydomonas reinhardtii was altered by single exchange of each cysteine (C115, C170, C362, and C366) with alanine, aspartate, or serine using site-directed mutagenesis. In contrast to cysteine 115, the other three cysteines were found to be dispensable for stable [4Fe-4S] cluster incorporation based on iron determination, UV/vis spectroscopy and electron paramagnetic resonance. However, the presence of a preformed [4Fe-4S] cluster alone does not guarantee stable incorporation of the [2Fe] cluster. Only variants C170D, C170S, C362D, and C362S showed characteristic signals for an inserted [2Fe] cluster in Fourier-transform infrared spectroscopy. Hydrogen evolution and oxidation were observed for these variants in solution based assays and protein-film electrochemistry. Catalytic activity was lowered for all variants and the ability to operate in either direction was also influenced.

| S-EPMC5855289 | biostudies-literature

Borane-protected cyanides as surrogates of H-bonded cyanides in [FeFe]-hydrogenase active site models.

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