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Watschinger K, Fuchs J, Yarov-Yarovoy V, Keller M, Golderer G, Hermetter A, Werner-Felmayer G, Hulo N, Werner E. Catalytic residues and a predicted structure of tetrahydrobiopterin-dependent alkylglycerol mono-oxygenase. Biochem J 2012; 443:279-86. [PMID: 22220568 PMCID: PMC3304488 DOI: 10.1042/bj20111509] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 12/22/2011] [Accepted: 01/06/2012] [Indexed: 11/17/2022]
Abstract
Alkylglycerol mono-oxygenase (EC 1.14.16.5) forms a third, distinct, class among tetrahydrobiopterin-dependent enzymes in addition to aromatic amino acid hydroxylases and nitric oxide synthases. Its protein sequence contains the fatty acid hydroxylase motif, a signature indicative of a di-iron centre, which contains eight conserved histidine residues. Membrane enzymes containing this motif, including alkylglycerol mono-oxygenase, are especially labile and so far have not been purified to homogeneity in active form. To obtain a first insight into structure-function relationships of this enzyme, we performed site-directed mutagenesis of 26 selected amino acid residues and expressed wild-type and mutant proteins containing a C-terminal Myc tag together with fatty aldehyde dehydrogenase in Chinese-hamster ovary cells. Among all of the acidic residues within the eight-histidine motif, only mutation of Glu137 to alanine led to an 18-fold increase in the Michaelis-Menten constant for tetrahydrobiopterin, suggesting a role in tetrahydrobiopterin interaction. A ninth additional histidine residue essential for activity was also identified. Nine membrane domains were predicted by four programs: ESKW, TMHMM, MEMSAT and Phobius. Prediction of a part of the structure using the Rosetta membrane ab initio method led to a plausible suggestion for a structure of the catalytic site of alkylglycerol mono-oxygenase.
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Affiliation(s)
- Katrin Watschinger
- *Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3/VI, A-6020 Innsbruck, Austria
| | - Julian E. Fuchs
- †Institute of General, Inorganic and Theoretical Chemistry, Innrain 52a, Leopold Franzens University Innsbruck, A-6020 Innsbruck, Austria
| | - Vladimir Yarov-Yarovoy
- ‡Department of Physiology and Membrane Biology, School of Medicine, Room 4131, Tupper Hall, University of California, Davis, One Shields Avenue, Davis, CA 95616, U.S.A
| | - Markus A. Keller
- *Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3/VI, A-6020 Innsbruck, Austria
| | - Georg Golderer
- *Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3/VI, A-6020 Innsbruck, Austria
| | - Albin Hermetter
- §Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, A-8010 Graz, Austria
| | - Gabriele Werner-Felmayer
- *Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3/VI, A-6020 Innsbruck, Austria
| | - Nicolas Hulo
- ∥Swiss Institute for Bioinformatics, Centre Medical Universitaire, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Ernst R. Werner
- *Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3/VI, A-6020 Innsbruck, Austria
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Chen C, Kim HL, Zhuang N, Seo KH, Park KH, Han CD, Park YS, Lee KH. Structural insights into the dual substrate specificities of mammalian and Dictyostelium dihydropteridine reductases toward two stereoisomers of quinonoid dihydrobiopterin. FEBS Lett 2011; 585:2640-6. [PMID: 21819985 DOI: 10.1016/j.febslet.2011.07.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 07/04/2011] [Accepted: 07/13/2011] [Indexed: 11/25/2022]
Abstract
Up to now, d-threo-tetrahydrobiopterin (DH(4), dictyopterin) was detected only in Dictyostelium discoideum, while the isomer L-erythro-tetrahydrobioterin (BH(4)) is common in mammals. To elucidate the mechanism of DH(4) regeneration by D. discoideum dihydropteridine reductase (DicDHPR), we have determined the crystal structure of DicDHPR complexed with NAD(+) at 2.16 Å resolution. Significant structural differences from mammalian DHPRs are found around the coenzyme binding site, resulting in a higher K(m) value for NADH (K(m)=46.51±0.4 μM) than mammals. In addition, we have found that rat DHPR as well as DicDHPR could bind to both substrates quinonoid-BH(2) and quinonoid-DH(2) by docking calculations and have confirmed their catalytic activity by in vitro assay.
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Affiliation(s)
- Cong Chen
- Division of Applied Life Science (BK21 Program), Gyeongsang National University, Jinju, Republic of Korea
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Watschinger K, Keller MA, Golderer G, Hermann M, Maglione M, Sarg B, Lindner HH, Hermetter A, Werner-Felmayer G, Konrat R, Hulo N, Werner ER. Identification of the gene encoding alkylglycerol monooxygenase defines a third class of tetrahydrobiopterin-dependent enzymes. Proc Natl Acad Sci U S A 2010; 107:13672-7. [PMID: 20643956 PMCID: PMC2922233 DOI: 10.1073/pnas.1002404107] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alkylglycerol monooxygenase (glyceryl-ether monooxygenase, EC 1.14.16.5) is the only enzyme known to cleave the O-alkyl bond of ether lipids which are essential components of brain membranes, protect the eye from cataract, interfere or mediate signalling processes, and are required for spermatogenesis. Along with phenylalanine hydroxylase, tyrosine hydroxylase, tryptophan hydroxylase, and nitric oxide synthase, alkylglycerol monooxygenase is one of five known enzymatic reactions which depend on tetrahydrobiopterin. Although first described in 1964, no sequence had been assigned to this enzyme so far since it lost activity upon protein purification attempts. A functional library screen using pools of plasmids of a rat liver expression library transfected to CHO cells was also unsuccessful. We therefore selected human candidate genes by bioinformatic approaches and by proteomic analysis of partially purified enzyme and tested alkylglycerol monooxygenase activity in CHO cells transfected with expression plasmids. Transmembrane protein 195, a predicted membrane protein with unassigned function which occurs in bilateral animals, was found to encode for tetrahydrobiopterin-dependent alkylglycerol monooxygenase. This sequence assignment was confirmed by injection of transmembrane protein 195 cRNA into Xenopus laevis oocytes. Transmembrane protein 195 shows no sequence homology to aromatic amino acid hydroxylases or nitric oxide synthases, but contains the fatty acid hydroxylase motif. This motif is found in enzymes which contain a diiron center and which carry out hydroxylations of lipids at aliphatic carbon atoms like alkylglycerol monooxygenase. This sequence assignment suggests that alkylglycerol monooxygenase forms a distinct third group among tetrahydrobiopterin-dependent enzymes.
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Affiliation(s)
- Katrin Watschinger
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Markus A. Keller
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Georg Golderer
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Martin Hermann
- Department of Visceral-, Transplant-, and Thoracic Surgery, Daniel-Swarovski-Research Laboratory, Innsbruck Medical University, Innrain 66, A-6020 Innsbruck, Austria
| | - Manuel Maglione
- Department of Visceral-, Transplant-, and Thoracic Surgery, Daniel-Swarovski-Research Laboratory, Innsbruck Medical University, Innrain 66, A-6020 Innsbruck, Austria
| | - Bettina Sarg
- Division of Clinical Biochemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Herbert H. Lindner
- Division of Clinical Biochemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Albin Hermetter
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, A-8010 Graz, Austria
| | - Gabriele Werner-Felmayer
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Robert Konrat
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter Campus 5, A-1030 Vienna, Austria; and
| | - Nicolas Hulo
- Centre Medical Universitaire and Structural Biology and Bioinformatics Department, 1 Rue Michel-Servet, CH-1211 Geneva 4, Switzerland
| | - Ernst R. Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
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Watschinger K, Keller MA, Hermetter A, Golderer G, Werner-Felmayer G, Werner ER. Glyceryl ether monooxygenase resembles aromatic amino acid hydroxylases in metal ion and tetrahydrobiopterin dependence. Biol Chem 2009; 390:3-10. [PMID: 19007315 PMCID: PMC2847825 DOI: 10.1515/bc.2009.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Glyceryl ether monooxygenase is a tetrahydrobiopterin-dependent membrane-bound enzyme which catalyses the cleavage of lipid ethers into glycerol and the corresponding aldehyde. Despite many different characterisation and purification attempts, so far no gene and primary sequence have been assigned to this enzyme. The seven other tetrahydrobiopterin-dependent enzymes can be divided in the family of aromatic amino acid hydroxylases - comprising phenylalanine hydroxylase, tyrosine hydroxylase and the two tryptophan hydroxylases - and into the three nitric oxide synthases. We tested the influences of different metal ions and metal ion chelators on glyceryl ether monooxygenase, phenylalanine hydroxylase and nitric oxide synthase activity to elucidate the relationship of glyceryl ether monooxygenase to these two families. 1,10-Phenanthroline, an inhibitor of non-heme iron-dependent enzymes, was able to potently block glyceryl ether monooxygenase as well as phenylalanine hydroxylase, but had no effect on inducible nitric oxide synthase. Two tetrahydrobiopterin analogues, N(5)-methyltetrahydrobiopterin and 4-aminotetrahydrobiopterin, had a similar impact on glyceryl ether monooxygenase activity, as has already been shown for phenylalanine hydroxylase. These observations point to a close analogy of the role of tetrahydrobiopterin in glyceryl ether monooxygenase and in aromatic amino acid hydroxylases and suggest that glyceryl ether monooxygenase may require a non-heme iron for catalysis.
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Affiliation(s)
- Katrin Watschinger
- Division of Biological Chemistry, Biocentre, Innsbruck Medical University, Fritz-Preglstr. 3/VI, A-6020 Innsbruck, Austria
| | - Markus A. Keller
- Division of Biological Chemistry, Biocentre, Innsbruck Medical University, Fritz-Preglstr. 3/VI, A-6020 Innsbruck, Austria
| | - Albin Hermetter
- Institute of Biochemistry, Graz University of Technology, Petersgasse 2/2, A-8010 Graz, Austria
| | - Georg Golderer
- Division of Biological Chemistry, Biocentre, Innsbruck Medical University, Fritz-Preglstr. 3/VI, A-6020 Innsbruck, Austria
| | - Gabriele Werner-Felmayer
- Division of Biological Chemistry, Biocentre, Innsbruck Medical University, Fritz-Preglstr. 3/VI, A-6020 Innsbruck, Austria
| | - Ernst R. Werner
- Division of Biological Chemistry, Biocentre, Innsbruck Medical University, Fritz-Preglstr. 3/VI, A-6020 Innsbruck, Austria
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Werner ER, Hermetter A, Prast H, Golderer G, Werner-Felmayer G. Widespread occurrence of glyceryl ether monooxygenase activity in rat tissues detected by a novel assay. J Lipid Res 2007; 48:1422-7. [PMID: 17303893 PMCID: PMC2851153 DOI: 10.1194/jlr.d600042-jlr200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An assay was set up for glyceryl ether monooxygenase activity in tissue samples using the novel substrate 1-O-pyrenedecyl-sn-glycerol and high-performance liquid chromatographic analysis of reaction mixtures with fluorescence detection, allowing robust detection of enzymatic activity in microgram amounts of tissue homogenates. The activity partially purified from rat liver strictly depended on the presence of a tetrahydropteridine. Tetrahydrobiopterin-dependent glyceryl ether monooxygenase activity was observed in all rat tissues tested except female heart, with highest activities in liver, intestine, and cerebellum. Activity was not uniformly distributed in brain: it was higher in cerebellum than in striatum or cortex. These data demonstrate that tetrahydrobiopterin-dependent glyceryl ether monooxygenase is found not only in liver and the gastrointestinal tract but also in brain and other organs of the rat and provide an additional goal for tetrahydrobiopterin biosynthesis in these organs.
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Affiliation(s)
- Ernst R Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, A-6020 Innsbruck, Austria.
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