title: An [Fe] hydrogenase from the anaerobic hydrogenosome-containing fungus Neocallimastix frontalis L2.
abstract: Hydrogenases, oxygen-sensitive enzymes that can make hydrogen gas, are key to the function of hydrogen-producing organelles (hydrogenosomes), which occur in anaerobic eukaryotes scattered throughout the eukaryotic tree. All of the eukaryotic enzymes characterized so far are iron-only [Fe] hydrogenases. In contrast, it has previously been suggested that hydrogenosomes of the best-studied anaerobic fungus Neocallimastix frontalis L2 contain an unrelated iron-nickel-selenium [NiFeSe] hydrogenase. We have isolated a gene from strain L2 that encodes a putative protein containing all of the characteristic features of an iron-only [Fe] hydrogenase, including the cysteine residues required for the co-ordination of the unique 'hydrogen cluster'. As is the case for experimentally verified hydrogenosomal matrix enzymes from N. frontalis, the [Fe] hydrogenase encodes a plausible amino terminal extension that resembles mitochondrial targeting signals. Phylogenetic analyses of an expanded [Fe] hydrogenase dataset reveal a complicated picture that is difficult to interpret in the light of current ideas of species relationships. Nevertheless, our analyses cannot reject the hypothesis that the novel [Fe] hydrogenase gene of Neocallimastix is specifically related to other eukaryote [Fe] hydrogenases, and thus ultimately might be traced to the same ancestral source.
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, UK.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Davidson
authors.forename: Mark
authors.initials: M
authors.lastname: van der Giezen
authors.forename: David S
authors.initials: DS
authors.lastname: Horner
authors.forename: T Martin
authors.initials: TM
authors.lastname: Embley
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Howe
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001482:Base Composition; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D006864:Hydrogenase / Q000737:chemistry / Q000235:genetics*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D020088:Neocallimastix / Q000201:enzymology / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D007506:Iron-Sulfur Proteins; C118830:iron hydrogenase; D006864:Hydrogenase