title: Metabolism of β-valine via a CoA-dependent ammonia lyase pathway.
abstract: Pseudomonas species strain SBV1 can rapidly grow on medium containing β-valine as a sole nitrogen source. The tertiary amine feature of β-valine prevents direct deamination reactions catalyzed by aminotransferases, amino acid dehydrogenases, and amino acid oxidases. However, lyase- or aminomutase-mediated conversions would be possible. To identify enzymes involved in the degradation of β-valine, a PsSBV1 gene library was prepared and used to complement the β-valine growth deficiency of a closely related Pseudomonas strain. This resulted in the identification of a gene encoding β-valinyl-coenzyme A ligase (BvaA) and two genes encoding β-valinyl-CoA ammonia lyases (BvaB1 and BvaB2). The BvaA protein demonstrated high sequence identity to several known phenylacetate CoA ligases. Purified BvaA enzyme did not convert phenyl acetic acid but was able to activate β-valine in an adenosine triphosphate (ATP)- and CoA-dependent manner. The substrate range of the enzyme appears to be narrow, converting only β-valine and to a lesser extent, 3-aminobutyrate and β-alanine. Characterization of BvaB1 and BvaB2 revealed that both enzymes were able to deaminate β-valinyl-CoA to produce 3-methylcrotonyl-CoA, a common intermediate in the leucine degradation pathway. Interestingly, BvaB1 and BvaB2 demonstrated no significant sequence identity to known CoA-dependent ammonia lyases, suggesting they belong to a new family of enzymes. BLAST searches revealed that BvaB1 and BvaB2 show high sequence identity to each other and to several enoyl-CoA hydratases, a class of enzymes that catalyze a similar reaction with water instead of amine as the leaving group.
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Marleen
authors.initials: M
authors.lastname: Otzen
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Ciprian G
authors.initials: CG
authors.lastname: Crismaru
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Christiaan P
authors.initials: CP
authors.lastname: Postema
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Hein J
authors.initials: HJ
authors.lastname: Wijma
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Heberling
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Wiktor
authors.initials: W
authors.lastname: Szymanski
authors.affiliation: DSM Pharmaceutical Products, Geleen, The Netherlands.|BioBased Materials, Faculty of Humanities and Sciences, Maastricht University, Chemelot, The Netherlands.
authors.forename: Stefaan
authors.initials: S
authors.lastname: de Wildeman
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands. d.b.janssen@rug.nl.
authors.forename: Dick B
authors.initials: DB
authors.lastname: Janssen
mesh_terms: D000642:Ammonia-Lyases / Q000235:genetics / Q000378:metabolism*; D003065:Coenzyme A / Q000378:metabolism*; D015723:Gene Library; D005816:Genetic Complementation Test; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D011549:Pseudomonas / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D017385:Sequence Homology; D013379:Substrate Specificity; D014633:Valine / Q000378:metabolism*
chemical_list: D000642:Ammonia-Lyases; D014633:Valine; D003065:Coenzyme A
keywords: Ammonia lyase; BvaA; BvaB1; BvaB2; CoA ligase; β-valine