title: The surprising diversity of clostridial hydrogenases: a comparative genomic perspective.
abstract: Among the large variety of micro-organisms capable of fermentative hydrogen production, strict anaerobes such as members of the genus Clostridium are the most widely studied. They can produce hydrogen by a reversible reduction of protons accumulated during fermentation to dihydrogen, a reaction which is catalysed by hydrogenases. Sequenced genomes provide completely new insights into the diversity of clostridial hydrogenases. Building on previous reports, we found that [FeFe] hydrogenases are not a homogeneous group of enzymes, but exist in multiple forms with different modular structures and are especially abundant in members of the genus Clostridium. This unusual diversity seems to support the central role of hydrogenases in cell metabolism. In particular, the presence of multiple putative operons encoding multisubunit [FeFe] hydrogenases highlights the fact that hydrogen metabolism is very complex in this genus. In contrast with [FeFe] hydrogenases, their [NiFe] hydrogenase counterparts, widely represented in other bacteria and archaea, are found in only a few clostridial species. Surprisingly, a heteromultimeric Ech hydrogenase, known to be an energy-converting [NiFe] hydrogenase and previously described only in methanogenic archaea and some sulfur-reducing bacteria, was found to be encoded by the genomes of four cellulolytic strains: Clostridum cellulolyticum, Clostridum papyrosolvens, Clostridum thermocellum and Clostridum phytofermentans.
authors.affiliation: Center for Protein Engineering, University of Liège, Allée de la Chimie 3, B4000 Liège, Belgium.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Calusinska
authors.affiliation: Lehrstuhl für Biochemie der Pflanzen, AG, Photobiotechnologie, Ruhr - Universität Bochum, 44780 Bochum, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Happe
authors.affiliation: Center for Protein Engineering, University of Liège, Allée de la Chimie 3, B4000 Liège, Belgium.
authors.forename: Bernard
authors.initials: B
authors.lastname: Joris
authors.affiliation: Center for Protein Engineering, University of Liège, Allée de la Chimie 3, B4000 Liège, Belgium.
authors.forename: Annick
authors.initials: A
authors.lastname: Wilmotte
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D003013:Clostridium / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D016680:Genome, Bacterial; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009876:Operon
chemical_list: D007506:Iron-Sulfur Proteins; D006859:Hydrogen; C118830:iron hydrogenase; C043296:nickel-iron hydrogenase; D006864:Hydrogenase