title: A multidomain fusion protein in Listeria monocytogenes catalyzes the two primary activities for glutathione biosynthesis.
abstract: Glutathione is the predominant low-molecular-weight peptide thiol present in living organisms and plays a key role in protecting cells against oxygen toxicity. Until now, glutathione synthesis was thought to occur solely through the consecutive action of two physically separate enzymes, gamma-glutamylcysteine ligase and glutathione synthetase. In this report we demonstrate that Listeria monocytogenes contains a novel multidomain protein (termed GshF) that carries out complete synthesis of glutathione. Evidence for this comes from experiments which showed that in vitro recombinant GshF directs the formation of glutathione from its constituent amino acids and the in vivo effect of a mutation in GshF that abolishes glutathione synthesis, results in accumulation of the intermediate gamma-glutamylcysteine, and causes hypersensitivity to oxidative agents. We identified GshF orthologs, consisting of a gamma-glutamylcysteine ligase (GshA) domain fused to an ATP-grasp domain, in 20 gram-positive and gram-negative bacteria. Remarkably, 95% of these bacteria are mammalian pathogens. A plausible origin for GshF-dependent glutathione biosynthesis in these bacteria was the recruitment by a GshA ancestor gene of an ATP-grasp gene and the subsequent spread of the fusion gene between mammalian hosts, most likely by horizontal gene transfer.
authors.affiliation: Tel Aviv University, The George S. Wise Faculty of Life Sciences, Department of Molecular Microbiology and Biotechnology, Ramat Aviv, 69978, Tel Aviv, Israel.
authors.forename: Shubha
authors.initials: S
authors.lastname: Gopal
authors.forename: Ilya
authors.initials: I
authors.lastname: Borovok
authors.forename: Amos
authors.initials: A
authors.lastname: Ofer
authors.forename: Michaela
authors.initials: M
authors.lastname: Yanku
authors.forename: Gerald
authors.initials: G
authors.lastname: Cohen
authors.forename: Werner
authors.initials: W
authors.lastname: Goebel
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kreft
authors.forename: Yair
authors.initials: Y
authors.lastname: Aharonowitz
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018938:Caco-2 Cells; D002384:Catalysis; D004151:Dipeptides / Q000378:metabolism; D005978:Glutathione / Q000096:biosynthesis* / Q000378:metabolism; D005981:Glutathione Synthase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008025:Ligases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008089:Listeria monocytogenes / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D008088:Listeriosis / Q000382:microbiology*; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D004151:Dipeptides; D000255:Adenosine Triphosphate; D008025:Ligases; D005981:Glutathione Synthase; D005978:Glutathione; C017341:gamma-glutamylcysteine