Paul W. King

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Enzymes possessing the capacity to oxidize molecular hydrogen have developed convergently three class of enzymes leading to: [FeFe]-, [NiFe]-, and [FeS]-cluster-free hydrogenases. They differ in the composition and the structure of the active site metal centre and the sequence of the constituent structural polypeptides but they show one unifying feature,(More)
To identify genes necessary for the photoproduction of H(2) in Chlamydomonas reinhardtii, random insertional mutants were screened for clones unable to produce H(2). One of the identified mutants, denoted hydEF-1, is incapable of assembling an active [Fe] hydrogenase. Although the hydEF-1 mutant transcribes both hydrogenase genes and accumulates full-length(More)
We have isolated and characterized a second [Fe]-hydrogenase gene from the green alga, Chlamydomonas reinhardtii. The HydA2 gene encodes a protein of 505 amino acids that is 74% similar and 68% identical to the known HydA1 hydrogenase from C. reinhardtii. HydA2 contains all the conserved residues and motifs found in the catalytic core of the family of(More)
Maturation of [FeFe] hydrogenases requires the biosynthesis and insertion of the catalytic iron-sulfur cluster, the H cluster. Two radical S-adenosylmethionine (SAM) proteins proposed to function in H cluster biosynthesis, HydEF and HydG, were recently identified in the hydEF-1 mutant of the green alga Chlamydomonas reinhardtii (M. C. Posewitz, P. W. King,(More)
We report on a computational investigation of the passive transport of H2 and O2 between the external solution and the hydrogen-producing active site of CpI [FeFe]-hydrogenase from Clostridium pasteurianum. Two distinct methodologies for studying gas access are discussed and applied: (1) temperature-controlled locally enhanced sampling, and (2) volumetric(More)
The [Fe]-hydrogenase enzymes are highly efficient H(2) catalysts found in ecologically and phylogenetically diverse microorganisms, including the photosynthetic green alga, Chlamydomonas reinhardtii. Although these enzymes can occur in several forms, H(2) catalysis takes place at a unique [FeS] prosthetic group or H-cluster, located at the active site.(More)
The in vitro activation of the [FeFe] hydrogenase is accomplished by combining Escherichia coli cell extracts containing the heterologously expressed inactive HydA with extracts in which hydrogenase-specific maturation proteins HydE, HydF, and HydG are expressed in concert. Interestingly, the process of HydA activation occurs rapidly and in the absence of(More)
Ferredoxins (FDXs) can distribute electrons originating from photosynthetic water oxidation, fermentation, and other reductant-generating pathways to specific redox enzymes in different organisms. The six FDXs identified in Chlamydomonas reinhardtii are not fully characterized in terms of their biological function. In this report, we present data from the(More)
The [FeFe]- and [NiFe]-hydrogenases catalyze the formal interconversion between hydrogen and protons and electrons, possess characteristic non-protein ligands at their catalytic sites and thus share common mechanistic features. Despite the similarities between these two types of hydrogenases, they clearly have distinct evolutionary origins and likely(More)
The [FeFe] hydrogenases HydA1 and HydA2 in the green alga Chlamydomonas reinhardtii catalyze the final reaction in a remarkable metabolic pathway allowing this photosynthetic organism to produce H(2) from water in the chloroplast. A [2Fe-2S] ferredoxin is a critical branch point in electron flow from Photosystem I toward a variety of metabolic fates,(More)