title: Carboxyl-terminal processing of the cytoplasmic NAD-reducing hydrogenase of Alcaligenes eutrophus requires the hoxW gene product.
abstract: Two open reading frames (ORFs) were identified immediately downstream of the four structural genes for the soluble hydrogenase (SH) of Alcaligenes eutrophus H16. While a mutation in ORF2 had no obvious effect on hydrogen metabolism, an in-frame deletion in ORF1, subsequently designated hoxW, led to a complete loss of SH activity and hence a significant retardation of autotrophic growth on hydrogen. Hydrogen oxidation in the hoxW mutant was catalyzed by the second hydrogenase, a membrane-bound enzyme. Assembly of the four subunits of the SH was blocked in mutant cells, and HoxH, the hydrogen-activating subunit, accumulated as a precursor which was still capable of binding nickel. Protein sequencing revealed that HoxH isolated from the wild type terminates at His-464, whereas the C-terminal amino acid sequence of HoxH from the hoxW mutant is colinear with the deduced sequence. Processing of the HoxH precursor was restored in vitro by a cell extract containing HoxW. These results indicate that HoxW is a highly specific carboxyl-terminal protease which releases a 24-amino-acid peptide from HoxH prior to progression of subunit assembly.
authors.affiliation: Institut für Pflanzenphysiologie und Mikrobiologie, Freie Universität Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Thiemermann
authors.forename: J
authors.initials: J
authors.lastname: Dernedde
authors.forename: M
authors.initials: M
authors.lastname: Bernhard
authors.forename: W
authors.initials: W
authors.lastname: Schroeder
authors.forename: C
authors.initials: C
authors.lastname: Massanz
authors.forename: B
authors.initials: B
authors.lastname: Friedrich
mesh_terms: D000421:Alcaligenes / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D003593:Cytoplasm / Q000201:enzymology; D008058:Dihydrolipoamide Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D006859:Hydrogen / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016366:Open Reading Frames; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017384:Sequence Deletion; D012995:Solubility
chemical_list: D001426:Bacterial Proteins; D011498:Protein Precursors; D006859:Hydrogen; D010088:Oxidoreductases; C021376:hydrogen dehydrogenase; D008058:Dihydrolipoamide Dehydrogenase; D010450:Endopeptidases; C098852:HoxW protein, bacteria