title: Nit1 is a metabolite repair enzyme that hydrolyzes deaminated glutathione.
abstract: The mammalian geneNit1(nitrilase-like protein 1) encodes a protein that is highly conserved in eukaryotes and is thought to act as a tumor suppressor. Despite being ∼35% sequence identical to ω-amidase (Nit2), the Nit1 protein does not hydrolyze efficiently α-ketoglutaramate (a known physiological substrate of Nit2), and its actual enzymatic function has so far remained a puzzle. In the present study, we demonstrate that both the mammalian Nit1 and its yeast ortholog are amidases highly active toward deaminated glutathione (dGSH; i.e., a form of glutathione in which the free amino group has been replaced by a carbonyl group). We further show thatNit1-KO mutants of both human and yeast cells accumulate dGSH and the same compound is excreted in large amounts in the urine ofNit1-KO mice. Finally, we show that several mammalian aminotransferases (transaminases), both cytosolic and mitochondrial, can form dGSH via a common (if slow) side-reaction and provide indirect evidence that transaminases are mainly responsible for dGSH formation in cultured mammalian cells. Altogether, these findings delineate a typical instance of metabolite repair, whereby the promiscuous activity of some abundant enzymes of primary metabolism leads to the formation of a useless and potentially harmful compound, which needs a suitable "repair enzyme" to be destroyed or reconverted into a useful metabolite. The need for a dGSH repair reaction does not appear to be limited to eukaryotes: We demonstrate that Nit1 homologs acting as excellent dGSH amidases also occur inEscherichia coliand other glutathione-producing bacteria.
authors.affiliation: Walloon Excellence in Lifesciences and Biotechnology, B-1200 Brussels, Belgium; alessio.peracchi@unipr.it maria.veiga@uclouvain.be emile.vanschaftingen@uclouvain.be.|de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.|Department of Life Sciences, Laboratory of Biochemistry, Molecular Biology, and Bioinformatics, University of Parma, 43124 Parma, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Peracchi
authors.affiliation: Walloon Excellence in Lifesciences and Biotechnology, B-1200 Brussels, Belgium; alessio.peracchi@unipr.it maria.veiga@uclouvain.be emile.vanschaftingen@uclouvain.be.|de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Maria
authors.initials: M
authors.lastname: Veiga-da-Cunha
authors.affiliation: Japan Clinical Metabolomics Institute, Kahoku, Ishikawa 929-1174, Japan.|Human Genetics, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan.
authors.forename: Tomiko
authors.initials: T
authors.lastname: Kuhara
authors.affiliation: Luxembourg Centre for Systems Biomedicine, Université du Luxembourg, L-4367 Belvaux, Luxembourg.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Ellens
authors.affiliation: Luxembourg Centre for Systems Biomedicine, Université du Luxembourg, L-4367 Belvaux, Luxembourg.
authors.forename: Nicole
authors.initials: N
authors.lastname: Paczia
authors.affiliation: Ludwig Institute for Cancer Research, de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Stroobant
authors.affiliation: Walloon Excellence in Lifesciences and Biotechnology, B-1200 Brussels, Belgium.|de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Agnieszka K
authors.initials: AK
authors.lastname: Seliga
authors.affiliation: Walloon Excellence in Lifesciences and Biotechnology, B-1200 Brussels, Belgium.|de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Simon
authors.initials: S
authors.lastname: Marlaire
authors.affiliation: Walloon Excellence in Lifesciences and Biotechnology, B-1200 Brussels, Belgium.|de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Stephane
authors.initials: S
authors.lastname: Jaisson
authors.affiliation: Walloon Excellence in Lifesciences and Biotechnology, B-1200 Brussels, Belgium.|de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Guido T
authors.initials: GT
authors.lastname: Bommer
authors.affiliation: Department of Cancer Biology and Genetics, Ohio State University, Columbus, OH 43210.
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Cancer Biology and Genetics, Ohio State University, Columbus, OH 43210.
authors.forename: Kay
authors.initials: K
authors.lastname: Huebner
authors.affiliation: Luxembourg Centre for Systems Biomedicine, Université du Luxembourg, L-4367 Belvaux, Luxembourg.
authors.forename: Carole L
authors.initials: CL
authors.lastname: Linster
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595.
authors.forename: Arthur J L
authors.initials: AJL
authors.lastname: Cooper
authors.affiliation: Walloon Excellence in Lifesciences and Biotechnology, B-1200 Brussels, Belgium; alessio.peracchi@unipr.it maria.veiga@uclouvain.be emile.vanschaftingen@uclouvain.be.|de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Emile
authors.initials: E
authors.lastname: Van Schaftingen
mesh_terms: D000619:Aminohydrolases / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D003641:Deamination; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D051379:Mice; D018345:Mice, Knockout; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013379:Substrate Specificity; D000637:Transaminases / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D000637:Transaminases; D000619:Aminohydrolases; C021867:nitrilase; D005978:Glutathione
keywords: amidase; aminotransferases; deaminated glutathione; metabolite repair