1
|
Lajnaf R, Gharsallah H, Jridi M, Attia H, Ayadi MA. Antioxidant and antibacterial activities, interfacial and emulsifying properties of the apo and holo forms of purified camel and bovine α-lactalbumin. Int J Biol Macromol 2020; 165:205-213. [PMID: 32991904 DOI: 10.1016/j.ijbiomac.2020.09.201] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/19/2020] [Accepted: 09/22/2020] [Indexed: 01/23/2023]
Abstract
The antioxidant and antibacterial activities of camel and bovine α-lactalbumin (α-La) in both calcium-loaded (holo) and calcium-depleted (apo) forms were investigated and compared. Antioxidant assay showed that camel and bovine α-La exhibited significant Ferric-reducing antioxidant power (FRAP), ferrous iron-chelating activity (FCA) and antiradical activities especially in their apo form. Camel apo α-La also exhibited attractive antibacterial activities against Gram-negative bacteria (Pseudomonas aeruginosa) and against fungal pathogens species (Penicillium bilaiae, Aspergillus tamari and Aspergillus sclerotiorum). Likewise, emulsifying properties (emulsification ability (EAI) and stability (ESI) indexes) and the surface characteristics (surface hydrophobicity, ζ-potential and interfacial tension) of the α-La were assessed. Maximum EAI were found at pH 7.0, with higher EAI values for the camel apo α-La (EAI ~19.5 m2/g). This behavior was explained by its relative high surface hydrophobicity and its greater efficiency to reduce the surface tension at the oil-water interface. Furthermore, emulsions were found to be more stable at pH 7.0 compared to pH 5.0 (ESI ~50%) due to the higher electrostatic repulsive forces between oil droplets at pH 7.0 in consistence with the ζ-potential results. This study concluded that the camel apo α-La has antibacterial, antioxidant, and emulsifying properties in agricultural and food industries.
Collapse
Affiliation(s)
- Roua Lajnaf
- Alimentary Analysis Unit, National Engineering School of Sfax, BPW 3038 Sfax, Tunisia; Montpellier University, UMR IATE, Place E. Bataillon, 34095 Montpellier Cedex 5, France.
| | - Houda Gharsallah
- Alimentary Analysis Unit, National Engineering School of Sfax, BPW 3038 Sfax, Tunisia; Tunisian Olive Institute, University of Sfax, Tunisia
| | - Mourad Jridi
- National School of Engineering of Sfax (ENIS), University of Sfax, Laboratory of Enzyme Engineering and Microbiology, P.O. Box 1173, Sfax 3038, Tunisia; Higher Institute of Biotechnology of Beja, University of Jendouba, Beja, Tunisia
| | - Hamadi Attia
- Alimentary Analysis Unit, National Engineering School of Sfax, BPW 3038 Sfax, Tunisia
| | - M A Ayadi
- Alimentary Analysis Unit, National Engineering School of Sfax, BPW 3038 Sfax, Tunisia
| |
Collapse
|
2
|
Myrach T, Zhu A, Witte CP. The assembly of the plant urease activation complex and the essential role of the urease accessory protein G (UreG) in delivery of nickel to urease. J Biol Chem 2017; 292:14556-14565. [PMID: 28710280 PMCID: PMC5582847 DOI: 10.1074/jbc.m117.780403] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 07/11/2017] [Indexed: 12/24/2022] Open
Abstract
Urease is a ubiquitous nickel metalloenzyme. In plants, its activation requires three urease accessory proteins (UAPs), UreD, UreF, and UreG. In bacteria, the UAPs interact with urease and facilitate activation, which involves the channeling of two nickel ions into the active site. So far this process has not been investigated in eukaryotes. Using affinity pulldowns of Strep-tagged UAPs from Arabidopsis and rice transiently expressed in planta, we demonstrate that a urease-UreD-UreF-UreG complex exists in plants and show its stepwise assembly. UreG is crucial for nickel delivery because UreG-dependent urease activation in vitro was observed only with UreG obtained from nickel-sufficient plants. This activation competence could not be generated in vitro by incubation of UreG with nickel, bicarbonate, and GTP. Compared with their bacterial orthologs, plant UreGs possess an N-terminal extension containing a His- and Asp/Glu-rich hypervariable region followed by a highly conserved sequence comprising two potential HXH metal-binding sites. Complementing the ureG-1 mutant of Arabidopsis with N-terminal deletion variants of UreG demonstrated that the hypervariable region has a minor impact on activation efficiency, whereas the conserved region up to the first HXH motif is highly beneficial and up to the second HXH motif strictly required for activation. We also show that urease reaches its full activity several days after nickel becomes available in the leaves, indicating that urease activation is limited by nickel accessibility in vivo Our data uncover the crucial role of UreG for nickel delivery during eukaryotic urease activation, inciting further investigations of the details of this process.
Collapse
Affiliation(s)
- Till Myrach
- From the Freie Universität Berlin, Dahlem Centre of Plant Sciences, Department of Plant Biochemistry, Königin-Luise-Strasse 12-16, 14195 Berlin, Germany and
| | - Anting Zhu
- Leibniz Universität Hannover, Institute of Plant Nutrition, Molecular Nutrition and Biochemistry of Plants, Herrenhäuser Strasse 2, 30419 Hannover, Germany
| | - Claus-Peter Witte
- Leibniz Universität Hannover, Institute of Plant Nutrition, Molecular Nutrition and Biochemistry of Plants, Herrenhäuser Strasse 2, 30419 Hannover, Germany
| |
Collapse
|
3
|
Eronina TB, Mikhaylova VV, Chebotareva NA, Kurganov BI. Kinetic regime of thermal aggregation of holo- and apoglycogen phosphorylases b. Int J Biol Macromol 2016; 92:1252-1257. [PMID: 27527690 DOI: 10.1016/j.ijbiomac.2016.08.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 06/23/2016] [Accepted: 08/11/2016] [Indexed: 12/22/2022]
Abstract
To characterize the role of pyridoxal 5'-phosphate in stabilization of the conformation of muscle glycogen phosphorylase b (Phb), the mechanism of thermal aggregation for holo- and apoforms of Phb has been studied using dynamic light scattering. The order of aggregation with respect to the protein (n) for aggregation of holoPhb at 48°C is equal to 0.5 suggesting that the dissociative mechanism of denaturation is operative and denaturation is followed by rapid aggregation stage. In the case of aggregation of apoPhb at 37°C n=2 and the rate-limiting stage is aggregation of unfolded protein molecules.
Collapse
Affiliation(s)
- Tatiana B Eronina
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia.
| | - Valeriya V Mikhaylova
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Natalia A Chebotareva
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Boris I Kurganov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| |
Collapse
|
4
|
Li DF, Zhang JY, Hou Y, Liu L, Liu SJ, Liu W. Crystallization and preliminary crystallographic analysis of 2-aminophenol 1,6-dioxygenase complexed with substrate and with an inhibitor. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1337-40. [PMID: 23143244 PMCID: PMC3515376 DOI: 10.1107/s1744309112038705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 09/10/2012] [Indexed: 11/10/2022]
Abstract
Dioxygen activation implemented by nonhaem Fe(II) enzymes containing the 2-His-1-carboxylate facial triad has been extensively studied in recent years. Extradiol dioxygenase is the archetypal member of this superfamily and catalyzes the oxygenolytic ring opening of catechol analogues. Here, the crystallization and preliminary X-ray analysis of 2-aminophenol 1,6-dioxygenase, an enzyme representing a minor subset of extradiol dioxygenases that catalyze the fission of 2-aminophenol rather than catecholic compounds, is reported. Crystals of the holoenzyme with FeII and of complexes with the substrate 2-aminophenol and the suicide inhibitor 4-nitrocatechol were grown using the cocrystallization method under the same conditions as used for the crystallization of the apoenzyme. The crystals belonged to space group C2 and diffracted to 2.3-2.7 Å resolution; the crystal that diffracted to the highest resolution had unit-cell parameters a=270.24, b=48.39, c=108.55 Å, β=109.57°. All X-ray data sets collected from diffraction-quality crystals were suitable for structure determination.
Collapse
Affiliation(s)
- De-Feng Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Jia-Yue Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Yanjie Hou
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Lei Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Shuang-Jiang Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Wei Liu
- Institute of Immunology, The Third Military Medical University, Chongqing 400038, People’s Republic of China
| |
Collapse
|
5
|
Baños-Sanz JI, Sanz-Aparicio J, Brearley CA, González B. Expression, purification, crystallization and preliminary X-ray diffraction analysis of the apo form of InsP5 2-K from Arabidopsis thaliana. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:701-4. [PMID: 22684075 PMCID: PMC3370915 DOI: 10.1107/s1744309112017307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 04/18/2012] [Indexed: 11/10/2022]
Abstract
Inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IP(5) 2-K) is a key enzyme that catalyzes the synthesis of phytic acid (IP(6)) from inositol 1,3,4,5,6-pentakisphosphate (IP(5)) and ATP. The first structure of IP(5) 2-K, that from Arabidopsis thaliana, has been solved previously; it only crystallized in the presence of inositol, either the substrate IP(5) or the product IP(6), and failed to crystallize in its free state (without inositol). Based on structural analysis, a point mutation of IP(5) 2-K (W129A) has been produced in order to overcome this limitation and obtain information about protein conformational changes upon substrate binding. Here, the production and crystallization of W129A IP(5) 2-K in its free state and with bound nucleotide is described. These crystals differed from the native crystals and belonged to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 66.00, b = 68.23, c = 105.80 Å and a = 63.06, b = 71.80, c = 100.23 Å, respectively. The crystals diffracted to resolutions of 2.22 Å (apo) and 2.05 Å (nucleotide bound) using synchrotron radiation and contained one molecule per asymmetric unit. The structures have been determined using the molecular-replacement method and refinement is being undertaken.
Collapse
Affiliation(s)
- Jose Ignacio Baños-Sanz
- Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química-Física ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Julia Sanz-Aparicio
- Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química-Física ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Charles A. Brearley
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, England
| | - Beatriz González
- Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química-Física ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain
| |
Collapse
|
6
|
Zhang J, Zhang X, Wu C, Lu D, Guo G, Mao X, Zhang Y, Wang DC, Li D, Zou Q. Expression, purification and characterization of arginase from Helicobacter pylori in its apo form. PLoS One 2011; 6:e26205. [PMID: 22028830 PMCID: PMC3197605 DOI: 10.1371/journal.pone.0026205] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 09/22/2011] [Indexed: 01/16/2023] Open
Abstract
Arginase, a manganese-dependent enzyme that widely distributed in almost all creatures, is a urea cycle enzyme that catalyzes the hydrolysis of L-arginine to generate L-ornithine and urea. Compared with the well-studied arginases from animals and yeast, only a few eubacterial arginases have been characterized, such as those from H. pylori and B. anthracis. However, these enzymes used for arginase activity assay were all expressed with LB medium, as low concentration of Mn2+ was detectable in the medium, protein obtained were partially Mn2+ bonded, which may affect the results of arginase activity assay. In the present study, H. pylori arginase (RocF) was expressed in a Mn2+ and Co2+ free minimal medium, the resulting protein was purified through affinity and gel filtration chromatography and the apo-form of RocF was confirmed by flame photometry analysis. Gel filtration indicates that the enzyme exists as monomer in solution, which was unique as compared with homologous enzymes. Arginase activity assay revealed that apo-RocF had an acidic pH optimum of 6.4 and exhibited metal preference of Co2+>Ni2+>Mn2+. We also confirmed that heat-activation and reducing regents have significant impact on arginase activity of RocF, and inhibits S-(2-boronoethyl)-L-Cysteine (BEC) and Nω-hydroxy-nor-Arginine (nor-NOHA) inhibit the activity of RocF in a dose-dependent manner.
Collapse
Affiliation(s)
- Jinyong Zhang
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, China
| | - Xiaoli Zhang
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, China
| | - Chao Wu
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, China
| | - Dongshui Lu
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, China
| | - Gang Guo
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, China
| | - Xuhu Mao
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, China
| | - Ying Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Da-Cheng Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Defeng Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- * E-mail: (DL); (QZ)
| | - Quanming Zou
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, China
- * E-mail: (DL); (QZ)
| |
Collapse
|
7
|
Lee JH, Park AK, Chi YM, Moon JH, Lee KS. Crystallization and preliminary X-ray crystallographic studies of enoyl-acyl carrier protein reductase (FabI) from Psuedomonas aeruginosa. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:214-6. [PMID: 21301088 PMCID: PMC3034610 DOI: 10.1107/s1744309110048827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 11/22/2010] [Indexed: 01/01/2023]
Abstract
During fatty-acid biosynthesis, enoyl-acyl carrier protein (enoyl-ACP) reductase catalyzes the reduction of trans-2-enoyl-ACP to fully saturated acyl-ACP via the ubiquitous fatty-acid synthase system. NADH-dependent enoyl-ACP reductase (FabI) from Pseudomonas aeruginosa has been purified and crystallized as an apoenzyme and in a complex form with NADH and triclosan. Triclosan is an inhibitor of FabI and forms a stable ternary complex in the presence of NADH. The crystals of native and complexed FabI diffracted to resolutions of 2.6 and 1.8 Å, respectively. The crystals both belonged to space group P2(1), with unit-cell parameters a = 117.32, b = 155.844, c = 129.448 Å, β = 111.061° for the native enzyme and a = 64.784, b = 107.573, c = 73.517 Å, β = 116.162° for the complex. Preliminary molecular replacement further confirmed the presence of four tetramers of native FabI and one tetramer of the complex in the asymmetric unit, corresponding to Matthews coefficients (V(M)) of 2.46 and 2.05 Å(3) Da(-1) and solvent contents of 50.1 and 40.1%, respectively.
Collapse
Affiliation(s)
- Jeong Hye Lee
- Division of Biotechnology, College of Life Sciences, Korea University, Seoul 136-713, Republic of Korea
| | - Ae Kyung Park
- Division of Biotechnology, College of Life Sciences, Korea University, Seoul 136-713, Republic of Korea
| | - Young Min Chi
- Division of Biotechnology, College of Life Sciences, Korea University, Seoul 136-713, Republic of Korea
| | - Jin Ho Moon
- Institute of Life Sciences and Natural Resources, Korea University, Seoul 136-713, Republic of Korea
| | - Ki Seog Lee
- Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan 609-757, Republic of Korea
| |
Collapse
|
8
|
Mukherjee S, Saha B, Dutta D, Das AK. Purification, crystallization and preliminary X-ray analysis of apo glyceraldehyde-3-phosphate dehydrogenase 1 (GAP1) from methicillin-resistant Staphylococcus aureus (MRSA252). Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:506-8. [PMID: 20445245 PMCID: PMC2864678 DOI: 10.1107/s1744309110007980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2010] [Accepted: 03/02/2010] [Indexed: 11/11/2022]
Abstract
Glyceraldehyde-3-phosphate dehydrogenase 1 (GAP1) from methicillin-resistant Staphylococcus aureus (MRSA252) has been purified to homogeneity in the apo form. The protein was crystallized using the hanging-drop vapour-diffusion method. The crystals belonged to space group P2(1), with unit-cell parameters a = 69.95, b = 93.68, c = 89.05 A, beta = 106.84 degrees . X-ray diffraction data have been collected and processed to a maximum resolution of 2.2 A. The presence of one tetramer in the asymmetric unit gives a Matthews coefficient (V(M)) of 1.81 A(3) Da(-1) with a solvent content of 32%. The structure has been solved by molecular replacement and structure refinement is now in progress.
Collapse
Affiliation(s)
- Somnath Mukherjee
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721 302, India
| | - Baisakhee Saha
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721 302, India
| | - Debajyoti Dutta
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721 302, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721 302, India
| |
Collapse
|
9
|
Banci L, Bertini I, D'Amelio N, Libralesso E, Turano P, Valentine JS. Metalation of the amyotrophic lateral sclerosis mutant glycine 37 to arginine superoxide dismutase (SOD1) apoprotein restores its structural and dynamical properties in solution to those of metalated wild-type SOD1. Biochemistry 2007; 46:9953-62. [PMID: 17683122 DOI: 10.1021/bi700620r] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The G37R copper-zinc superoxide dismutase (SOD1) is one of the many mutant SOD1 proteins known to cause familial amyotrophic lateral sclerosis by an unknown mechanism. This particular mutation occurs in the beta barrel plug, a region proposed to be critical for the structural stability of the protein. The behavior of G37R asSOD1 was studied in solution where it was observed that, when the protein is fully metalated, its global structure, mobility, and stability are virtually indistinguishable from those of the nonmutated protein. By contrast, although the presence of the G37R mutation does not result in a substantial change of the overall structure of the metal-free apoprotein in solution, it does affect the key conformational features of the beta-barrel plug such that (i) apo G37R asSOD1 melts at a temperature approximately 10 degrees C lower than apo asSOD1, (ii) it aggregates more rapidly than apo asSOD1, and (iii) interaction with trifluoroethanol (TFE) can deform it into a structure with a much higher degree of alpha-helical content. The increased plasticity of the apo G37R asSOD1 mutant protein is likely responsible for its enhanced tendency to aggregate in concentrated solutions. These results suggest further that it is the metal-free apo forms of the mutant SOD1 protein that are the agents of its toxicity.
Collapse
Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
| | | | | | | | | | | |
Collapse
|
10
|
Voronova A, Kazantseva J, Tuuling M, Sokolova N, Sillard R, Palumaa P. Cox17, a copper chaperone for cytochrome c oxidase: Expression, purification, and formation of mixed disulphide adducts with thiol reagents. Protein Expr Purif 2007; 53:138-44. [PMID: 17208454 DOI: 10.1016/j.pep.2006.11.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 11/21/2006] [Accepted: 11/22/2006] [Indexed: 10/23/2022]
Abstract
Copper chaperone for cytochrome c oxidase (Cox17) is a 7 kDa copper-binding protein, which facilitates incorporation of copper ions into Cu(A) site of cytochrome c oxidase. Cox17 contains six conserved Cys residues and occurs in three different oxidative states, which display different metal-binding properties and stability. In the present study, we have elaborated technologies for production of partially oxidized human recombinant Cox17 in a bacterial expression system and purification of fully oxidized Cox17. For this purpose we used Escherichia coli Origami strain, which is deficient in thioredoxin and thioredoxin reductase systems and allows formation of disulfide bonds in cytoplasmic proteins. Fully oxidized Cox17 was purified by a simplified two-step procedure including gel filtration and cation exchange chromatography. By using mass spectrometry we demonstrated that application of 2-mercaptoethanol (2-ME) during purification leads to formation of its mixed disulfide adducts with Cox17. Moreover, partially reduced Cox17 can form mixed disulfide adducts also with the cellular reducing agent glutathione, which abolishes copper-binding ability of partially reduced Cox17.
Collapse
Affiliation(s)
- Anastassia Voronova
- Institute of Gene Technology, Tallinn Technical University, Akadeemia tee 15, EE-12618 Tallinn, Estonia
| | | | | | | | | | | |
Collapse
|
11
|
Youn B, Kim SJ, Moinuddin SGA, Lee C, Bedgar DL, Harper AR, Davin LB, Lewis NG, Kang C. Mechanistic and structural studies of apoform, binary, and ternary complexes of the Arabidopsis alkenal double bond reductase At5g16970. J Biol Chem 2006; 281:40076-88. [PMID: 17028190 DOI: 10.1074/jbc.m605900200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we determined the crystal structures of the apoform, binary, and ternary complexes of the Arabidopsis alkenal double bond reductase encoded by At5g16970. This protein, one of 11 homologues in Arabidopsis thaliana, is most closely related to the Pinus taeda phenylpropenal double bond reductase, involved in, for example, heartwood formation. Both enzymes also have essential roles in plant defense, and can function by catalyzing the reduction of the 7-8-double bond of phenylpropanal substrates, such as p-coumaryl and coniferyl aldehydes in vitro. At5g16970 is also capable of reducing toxic substrates with the same alkenal functionality, such as 4-hydroxy-(2E)-nonenal. The overall fold of At5g16970 is similar to that of the zinc-independent medium chain dehydrogenase/reductase superfamily, the members of which have two domains and are dimeric in nature, i.e. in contrast to their original classification as being zinc-containing oxidoreductases. As provisionally anticipated from the kinetic data, the shape of the binding pocket can readily accommodate p-coumaryl aldehyde, coniferyl aldehyde, 4-hydroxy-(2E)-nonenal, and 2-alkenals. However, the enzyme kinetic data among these potential substrates differ, favoring p-coumaryl aldehyde. Tyr-260 is provisionally proposed to function as a general acid/base for hydride transfer. A catalytic mechanism for this reduction, and its applicability to related important detoxification mammalian proteins, is also proposed.
Collapse
Affiliation(s)
- Buhyun Youn
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Xu L, Zhang D, Mu W, van Berkel WJH, Luo Z. Reversible resolution of flavin and pterin cofactors of His-tagged Escherichia coli DNA photolyase. Biochim Biophys Acta 2006; 1764:1454-61. [PMID: 16938496 DOI: 10.1016/j.bbapap.2006.06.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 06/05/2006] [Accepted: 06/13/2006] [Indexed: 11/23/2022]
Abstract
Escherichia coli photolyase catalyzes the repair of cyclobutane pyrimidine dimers (CPD) in DNA under near UV/blue-light irradiation. The enzyme contains flavin adenine dinucleotide (FAD) and methenyltetrahydrofolate (MTHF) as noncovalently bound light sensing cofactors. To study the apoprotein-chromophore interactions we developed a new procedure to prepare apo-photolyase. MTHF-free photolyase was obtained by binding the C-terminal His-tagged holoenzyme to a metal-affinity column at neutral pH and washing the column with deionized water. Under these conditions the flavin remains bound and the defolated enzyme can be released from the column with 0.5 M imidazole pH 7.2. The MTHF-free protein was still capable of DNA repair, showing 70% activity of native enzyme. Fluorescence polarization experiments confirmed that MTHF binding is weakened at low ionic strength. Apo-photolyase was obtained by treating the His-tagged holoenzyme with 0.5 M imidazole pH 10.0. The apo-photolyase thus obtained was highly reconstitutable and bound nearly stoichiometric amounts of FAD(ox). Photolyase reconstituted with FAD(ox) had about 34% activity of native enzyme, which increased to 83% when FAD(ox) was reduced to FADH(-). Reconstitution kinetics performed at 20 degrees C showed that apo-photolyase associates with FADH(-) much faster (k(obs) approximately 3,000 M(-1) s(-1)) than with FAD(ox) (k(obs)=16 [corrected] M(-1) s(-1)). The dissociation constant of the photolyase-FAD(ox) complex is about 2.3 microM and that of E-FADH(-) is not higher than 20 nM (pH 7.2).
Collapse
Affiliation(s)
- Lei Xu
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.
| | | | | | | | | |
Collapse
|
13
|
Inagaki E, Sakamoto K, Obayashi N, Terada T, Shirouzu M, Bessho Y, Kuroishi C, Kuramitsu S, Shinkai A, Yokoyama S. Expression, purification, crystallization and preliminary X-ray diffraction analysis of galactokinase from Pyrococcus horikoshii. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:169-71. [PMID: 16511293 PMCID: PMC2150956 DOI: 10.1107/s1744309106001813] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 01/17/2006] [Indexed: 11/10/2022]
Abstract
Galactokinase (EC 2.7.1.6) catalyzes the ATP-dependent phosphorylation of alpha-D-galactose to alpha-D-galactose-1-phosphate, in an additional metabolic branch of glycolysis. The apo-form crystal structure of the enzyme has not yet been elucidated. Crystals of galactokinase from Pyrococcus horikoshii were prepared in both the apo form and as a ternary complex with alpha-D-galactose and an ATP analogue. Diffraction data sets were collected to 1.24 A resolution for the apo form and to 1.7 A for the ternary complex form using synchrotron radiation. The apo-form crystals belong to space group C2, with unit-cell parameters a = 108.08, b = 38.91, c = 81.57 A, beta = 109.8 degrees. The ternary complex form was isomorphous with the apo form, except for the length of the a axis. The galactokinase activity of the enzyme was confirmed and the kinetic parameters at 323 K were determined.
Collapse
Affiliation(s)
- Eiji Inagaki
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Keiko Sakamoto
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Naomi Obayashi
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Takaho Terada
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Mikako Shirouzu
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Yoshitaka Bessho
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Chizu Kuroishi
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Seiki Kuramitsu
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Akeo Shinkai
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Shigeyuki Yokoyama
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| |
Collapse
|
14
|
Hassan-Abdallah A, Bruckner RC, Zhao G, Jorns MS. Biosynthesis of covalently bound flavin: isolation and in vitro flavinylation of the monomeric sarcosine oxidase apoprotein. Biochemistry 2005; 44:6452-62. [PMID: 15850379 PMCID: PMC1993914 DOI: 10.1021/bi047271x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The covalently bound FAD in native monomeric sarcosine oxidase (MSOX) is attached to the protein by a thioether bond between the 8alpha-methyl group of the flavin and Cys315. Large amounts of soluble apoenzyme are produced by controlled expression in a riboflavin-dependent Escherichia coli strain. A time-dependent increase in catalytic activity is observed upon incubation of apoMSOX with FAD, accompanied by the covalent incorporation of FAD to approximately 80% of the level observed with the native enzyme. The spectral and catalytic properties of the reconstituted enzyme are otherwise indistinguishable from those of native MSOX. The reconstitution reaction exhibits apparent second-order kinetics (k = 139 M(-)(1) min(-)(1) at 23 degrees C) and is accompanied by the formation of a stoichiometric amount of hydrogen peroxide. A time-dependent reduction of FAD is observed when the reconstitution reaction is conducted under anaerobic conditions. The results provide definitive evidence for autoflavinylation in a reaction that proceeds via a reduced flavin intermediate and requires only apoMSOX and FAD. Flavinylation of apoMSOX is not observed with 5-deazaFAD or 1-deazaFAD, an outcome attributed to a decrease in the acidity of the 8alpha-methyl group protons. Covalent flavin attachment is observed with 8-nor-8-chloroFAD in an aromatic nucleophilic displacement reaction that proceeds via a quininoid intermediate but not a reduced flavin intermediate. The reconstituted enzyme contains a modified cysteine-flavin linkage (8-nor-8-S-cysteinyl) as compared with native MSOX (8alpha-S-cysteinyl), a difference that may account for its approximately 10-fold lower catalytic activity.
Collapse
Affiliation(s)
| | | | | | - Marilyn Schuman Jorns
- *To whom requests for reprints should be addressed. Phone: (215) 762-7495 FAX: (215) 762-4452, E-mail:
| |
Collapse
|
15
|
Merone L, Mandrich L, Rossi M, Manco G. A thermostable phosphotriesterase from the archaeon Sulfolobus solfataricus: cloning, overexpression and properties. Extremophiles 2005; 9:297-305. [PMID: 15909078 DOI: 10.1007/s00792-005-0445-4] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 02/28/2005] [Indexed: 10/25/2022]
Abstract
A new gene from the hyperthermophilic archaeon Sulfolobus solfataricus MT4, coding for a putative protein reported to show sequence identity with the phosphotriesterase-related protein family (PHP), was cloned by means of the polymerase chain reaction from the S. solfataricus genomic DNA. In order to analyse the biochemical properties of the protein an overexpression system in Escherichia coli was established. The recombinant protein, expressed in soluble form at 5 mg/l of E. coli culture, was purified to homogeneity and characterized. In contrast with its mesophilic E. coli counterpart that was devoid of any tested activity, the S. solfataricus enzyme was demonstrated to have a low paraoxonase activity. This activity was dependent from metal cations with Co(2+), Mg(2+) and Ni(2+) being the most effective and was thermophilic and thermostable. The enzyme was inactivated with EDTA and o-phenantroline. A reported inhibitor for Pseudomonas putida phosphotriesterase (PTE) had no effect on the S. solfataricus paraoxonase. The importance of a stable paraoxonase for detoxification of chemical warfare agents and agricultural pesticides will be discussed.
Collapse
Affiliation(s)
- Luigia Merone
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via P. Castellino, Napoli, Italy
| | | | | | | |
Collapse
|
16
|
Bailey MR, Woodard SL, Callaway E, Beifuss K, Magallanes-Lundback M, Lane JR, Horn ME, Mallubhotla H, Delaney DD, Ward M, Van Gastel F, Howard JA, Hood EE. Improved recovery of active recombinant laccase from maize seed. Appl Microbiol Biotechnol 2004; 63:390-7. [PMID: 12802534 DOI: 10.1007/s00253-003-1362-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2003] [Revised: 04/29/2003] [Accepted: 05/08/2003] [Indexed: 11/25/2022]
Abstract
Lignolytic enzymes such as laccase have been difficult to over-express in an active form. This paper describes the expression, characterization, and application of a fungal laccase in maize seed. The transgenic seed contains immobilized and extractable laccase. Fifty ppm dry weight of aqueously extractable laccase was obtained, and the remaining solids contained a significant amount of immobilized laccase that was active. Although a portion of the extractable laccase was produced as inactive apoenzyme, laccase activity was recovered by treatment with copper and chloride. In addition to allowing the apoenzyme to regain activity, treatment with copper also provided a partial purification step by precipitating other endogenous corn proteins while leaving >90% of the laccase in solution. The data also demonstrate the application of maize-produced laccase as a polymerization agent. The apparent concentration of laccase in ground, defatted corn germ is approximately 0.20% of dry weight.
Collapse
Affiliation(s)
- M R Bailey
- ProdiGene, 101 Gateway Blvd. Suite 100, College Station, TX 77845, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Miyamoto E, Watanabe F, Charles TC, Yamaji R, Inui H, Nakano Y. Purification and characterization of homodimeric methylmalonyl-CoA mutase from Sinorhizobium meliloti. Arch Microbiol 2003; 180:151-4. [PMID: 12844209 DOI: 10.1007/s00203-003-0570-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2003] [Revised: 05/15/2003] [Accepted: 05/26/2003] [Indexed: 11/24/2022]
Abstract
High activity (>60 munit/mg protein) of 5'-deoxyadenosylcobalamin-dependent methylmalonyl-CoA mutase (EC 5.4.99.2) was constantly found during growth of a strain of the root-nodule-forming bacterium Sinorhizobium meliloti harboring an extra plasmid-encoded copy of the methylmalonyl-CoA-mutase-encoding bhbA gene. The enzyme was purified to homogeneity and characterized. The purified enzyme was found to be a colorless apo-form. The apparent molecular weight of the enzyme was calculated to be 165,000+/-5,000 by Superdex 200 HR gel filtration. SDS-PAGE of the purified enzyme resolved one protein band with an apparent molecular mass of 80.0+/-2.0 kDa, indicating that the S. meliloti enzyme is composed of two identical subunits. The NH(2)-terminal sequence was identical to that predicted from the bhbA nucleotide sequence. Monovalent cations were required for enzyme activity.
Collapse
Affiliation(s)
- Emi Miyamoto
- Department of Health Science, Kochi Women's University, 780-8515, Kochi, Japan
| | | | | | | | | | | |
Collapse
|
18
|
Dikiy A, Carpentier W, Vandenberghe I, Borsari M, Safarov N, Dikaya E, Van Beeumen J, Ciurli S. Structural basis for the molecular properties of cytochrome c6. Biochemistry 2002; 41:14689-99. [PMID: 12475218 DOI: 10.1021/bi026473v] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This is a thorough biochemical, spectroscopic, electrochemical, and structural study of a cytochrome c(6) isolated from the filamentous green alga Cladophora glomerata. The protein sequence, elucidated using chemical and mass spectrometric techniques, features 91 amino acids and the characteristic CXXCH heme-binding motif found in c-type cytochromes. The protein is monomeric in both oxidation forms, thereby putting in question a functional role for protein dimerization. Direct electrochemical measurements established, for the first time, the kinetic and thermodynamic data for the redox process in a cytochrome c(6). In particular, the quasi-reversible and diffusion-controlled redox process is accompanied by negative enthalpy and entropy changes, resulting in an E degrees ' value of 0.352 V at 298 K. The pH-dependent properties of the oxidized protein, detected by UV-visible, NMR, and direct cyclic voltammetry, indicate the presence of two acid-base equilibria occurring in the acidic (pK(a) = 4.5) and alkaline regions (pK(a) = 9.0). NMR and electronic spectra allowed the assignment of these equilibria to deprotonation of heme propionate-7 and to replacement of the axial methionine with another ligand, respectively. The 1.3 A resolution X-ray structure of the oxidized protein, revealing a fold typical for class I cytochromes, suggests that the conserved Lys60 replaces the axial methionine at pH >9. The heme solvent accessibility is low, and no water molecules were found in the vicinity of the axial ligands of the heme Fe. A structure-based alignment of cytochromes c(6), and the direct comparison of their structures, indicate a substantial degree of identity between the tertiary structures and suggest patches involved in protein-protein interaction. In particular, the surface electrostatic potential of cytochromes c(6) features a hydrophobic region around the heme cofactor, and a backside surface rich in negative charges.
Collapse
Affiliation(s)
- Alexander Dikiy
- Department of Agro-Environmental Science and Technology, University of Bologna, Via Filippo Re 8, Italy
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Affiliation(s)
- Patricia L Bounds
- Laboratory of Inorganic Chemistry, Eidgenössische Technische Hochschule, CH-8093 Zurich, Switzerland
| | | | | |
Collapse
|
20
|
Lupidi G, Venardi G, Bollettini M, Marmocchi F, Rotilio G. Purification and partial characterization of glyoxalase I from bovine brain. Prep Biochem Biotechnol 2001; 31:305-16. [PMID: 11513094 DOI: 10.1081/pb-100104911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Glyoxalase I was purified to homogeneity from bovine brain using affinity chromatography on S-hexylglutathione-Sepharose 6B with a yield of 22%. The enzyme was a dimer (44,000 Daltons) composed of, apparently, identical subunits (22,000 Daltons), as shown by SDS electrophoresis, and contained one mole of Zn2+/monomer. The active site metal ion, Zn2+, was removed by dialysis against EDTA, but the activity of the apoenzyme obtained was not completely restored after addition of Co2+ and Zn2+ (<25%), while a recovery of 50% was obtained after addition of Mg2+. The enzyme was inhibited by S-bromobenzylglutathione and S-p-nitrobenzylglutathione with a Ki value of 21 microM and 32 microM, respectively. The highest dissociation constant observed for the brain enzyme with respect to that reported for human erythrocytes, or other mammalian forms of enzyme could be related to a tissue-specific dependence of the glyoxalase I activity.
Collapse
Affiliation(s)
- G Lupidi
- Dept. of Biology M.C.A., University of Camerino, Italy.
| | | | | | | | | |
Collapse
|
21
|
Zhou M, Lu ML, Qiu W, Campbell RL, Nahoum V, Lapointe J, Roy PH, Lin SX. Crystallization and preliminary X-ray diffraction analysis of the chloramphenicol acetyltransferase from Tn2424. Acta Crystallogr D Biol Crystallogr 2001; 57:281-3. [PMID: 11173480 DOI: 10.1107/s0907444900016802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2000] [Accepted: 11/09/2000] [Indexed: 11/10/2022]
Abstract
Crystals of chloramphenicol acetyltransferase B2, an enzyme encoded by the transposon Tn2424 from Escherichia coli, have been obtained utilizing polyethylene glycol as a precipitant. The enzyme inactivates the antibiotic chloramphenicol and is a member of the xenobiotic acetyltransferase family. Two crystal forms were obtained and complete data sets have been collected at a synchrotron source: form I, which diffracted to 3.2 A, and form II, grown in the presence of NiCl(2), for which crystals of the apoenzyme and of the enzyme-chloramphenicol complex have been obtained. For the form II crystals, complete data sets have been collected at 2.7 and 3.2 A resolution, respectively. The space group of the above two crystal forms is P2(1)3, with unit-cell parameter a = 130 A.
Collapse
Affiliation(s)
- M Zhou
- Molecular Endocrinology and Oncology Laboratory, CHUL Research Center and Laval University, Quebec, Canada
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Hemmens B, Goessler W, Schmidt K, Mayer B. Role of bound zinc in dimer stabilization but not enzyme activity of neuronal nitric-oxide synthase. J Biol Chem 2000; 275:35786-91. [PMID: 10954720 DOI: 10.1074/jbc.m005976200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitric-oxide synthases (NOS) are homodimeric proteins and can form an intersubunit Zn(4S) cluster. We have measured zinc bound to NOS purified from pig brain (0.6 mol/mol of NOS) and baculovirus-expressed rat neuronal NOS (nNOS) (0.49 +/- 0.13 mol/mol of NOS), by on-line gel-filtration/inductively coupled plasma mass spectrometry. Cobalt, manganese, molybdenum, nickel, and vanadium were all undetectable. Baculovirus-expressed nNOS also bound up to 2. 00 +/- 0.58 mol of copper/mol of NOS. Diethylenetriaminepentaacetic acid (DTPA) reduced the bound zinc to 0.28 +/- 0.07 and the copper to 0.97 +/- 0.24 mol/mol of NOS. Desalting of samples into thiol-free buffer did not affect the zinc content but completely eliminated the bound copper (</=0.02 mol/mol of NOS). Most (> or =75%) of the bound zinc was released from baculovirus-expressed rat nNOS by p-chloromercuriphenylsulfonic acid (PMPS). PMPS-treated nNOS was strongly (90 +/- 5%) inactivated. To isolate functional effects of zinc release from other effects of PMPS, PMPS-substituted thiols were unblocked by excess reduced thiol in the presence of DTPA, which hindered reincorporation of zinc. The resulting enzyme contained 0.12 +/- 0.05 mol of zinc but had a specific activity of 426 +/- 46 nmol of citrulline.mg(-1).min(-1), corresponding to 93 +/- 10% of non-PMPS-treated controls. PMPS also caused dissociation of nNOS dimers under native conditions, an effect that was blocked by the pteridine cofactor tetrahydrobiopterin (H(4)biopterin). H(4)biopterin did not affect zinc release. Even in the presence of H(4)biopterin, PMPS prevented conversion of NOS dimers to an SDS-resistant form. We conclude that zinc binding is a prerequisite for formation of SDS-resistant NOS dimers but is not essential for catalysis.
Collapse
Affiliation(s)
- B Hemmens
- Institut für Pharmakologie und Toxikologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, and Institut für Chemie, Karl-Franzens-Universität Graz, Universitätsplatz 1, Graz A-8010, Austria
| | | | | | | |
Collapse
|
23
|
Svensson S, Höög JO, Schneider G, Sandalova T. Crystal structures of mouse class II alcohol dehydrogenase reveal determinants of substrate specificity and catalytic efficiency. J Mol Biol 2000; 302:441-53. [PMID: 10970744 DOI: 10.1006/jmbi.2000.4039] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The structure of mouse class II alcohol dehydrogenase (ADH2) has been determined in a binary complex with the coenzyme NADH and in a ternary complex with both NADH and the inhibitor N-cyclohexylformamide to 2.2 A and 2.1 A resolution, respectively. The ADH2 dimer is asymmetric in the crystal with different orientations of the catalytic domains relative to the coenzyme-binding domains in the two subunits, resulting in a slightly different closure of the active-site cleft. Both conformations are about half way between the open apo structure and the closed holo structure of horse ADH1, thus resembling that of ADH3. The semi-open conformation and structural differences around the active-site cleft contribute to a substantially different substrate-binding pocket architecture as compared to other classes of alcohol dehydrogenase, and provide the structural basis for recognition and selectivity of alcohols and quinones. The active-site cleft is more voluminous than that of ADH1 but not as open and funnel-shaped as that of ADH3. The loop with residues 296-301 from the coenzyme-binding domain is short, thus opening up the pocket towards the coenzyme. On the opposite side, the loop with residues 114-121 stretches out over the inter-domain cleft. A cavity is formed below this loop and adds an appendix to the substrate-binding pocket. Asp301 is positioned at the entrance of the pocket and may control the binding of omega-hydroxy fatty acids, which act as inhibitors rather than substrates. Mouse ADH2 is known as an inefficient ADH with a slow hydrogen-transfer step. By replacing Pro47 with His, the alcohol dehydrogenase activity is restored. Here, the structure of this P47H mutant was determined in complex with NADH to 2.5 A resolution. His47 is suitably positioned to act as a catalytic base in the deprotonation of the substrate. Moreover, in the more closed subunit, the coenzyme is allowed a position closer to the catalytic zinc. This is consistent with hydrogen transfer from an alcoholate intermediate where the Pro/His replacement focuses on the function of the enzyme.
Collapse
Affiliation(s)
- S Svensson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | | | | | | |
Collapse
|
24
|
Heinz WJ, Kurzai O, Brakhage AA, Fonzi WA, Korting HC, Frosch M, Mühlschlegel FA. Molecular responses to changes in the environmental pH are conserved between the fungal pathogens Candida dubliniensis and Candida albicans. Int J Med Microbiol 2000; 290:231-8. [PMID: 10959725 DOI: 10.1016/s1438-4221(00)80120-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In this work we cloned CdPHR1 and CdPHR2 from the human fungal pathogen Candida dubliniensis. The two genes are homologues to the pH-regulated genes PHR1 and PHR2 from Candida albicans. The pH-dependent pattern of expression of CdPHR1 and CdPHR2 was conserved in C. dubliniensis. CdPHR1 could be shown to be functionally equivalent to PHR1. The pH-regulated mode of expression was maintained when CdPHR1 was integrated in C. albicans. This indicates a fundamentally similar mode of expressional regulation in the two species. CdPHR1 was furthermore capable of reversing the aberrant phenotype of a Saccharomyces cerevisiae GAS1 deletion mutant. In this species, however, expression of CdPHR1 was no longer under control of the external pH. Expression of CdPHR1 was not detected when it was introduced into Aspergillus nidulans. In conclusion, C. dubliniensis and C. albicans respond to changes in the environmental pH with a change in cell shape and differential gene expression.
Collapse
Affiliation(s)
- W J Heinz
- Institut für Hygiene und Mikrobiologie, Universität Würzburg, Germany
| | | | | | | | | | | | | |
Collapse
|
25
|
Teske JG, Savenkova MI, Mauro JM, Erman JE, Satterlee JD. Yeast cytochrome c peroxidase expression in Escherichia coli and rapid isolation of various highly pure holoenzymes. Protein Expr Purif 2000; 19:139-47. [PMID: 10833401 DOI: 10.1006/prep.2000.1220] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A more efficient 2-day isolation and purification method for recombinant yeast cytochrome c peroxidase produced in Escherichia coli is presented. Two types of recombinant "wild-type" CcP have been produced and characterized, the recombinant nuclear gene sequence and the 294-amino-acid original protein sequence. These two sequences constitute the majority of the recombinant "native" or wild-type CcP currently in production and from which all recombinant variants now derive. The enzymes have been subjected to extensive physical characterizations, including sequencing, UV-visible spectroscopy, HPLC, gel electrophoresis, kinetic measurements, NMR spectroscopy, and mass spectrometry. Less extensive characterization data are also presented for recombinant, perdeuterated CcP, an enzyme produced in >95% deuterated medium. All of these results indicate that the purified recombinant wild-type enzymes are functionally and spectroscopically identical to the native, yeast-isolated wild-type enzyme. This improved method uses standard chromatography to produce highly purified holoenzyme in a more efficient manner than previously achieved. Two methods for assembling the holoenzyme are described. In one, exogenous heme is added at lysis, while in the other heme biosynthesis is stimulated in E. coli. A primary reason for developing this method has been the need to minimize loss of precious, isotope-labeled enzyme and, so, this method has also been used to produce both the perdeuterated and the (15)N-labeled enzyme, as well as several variants.
Collapse
Affiliation(s)
- J G Teske
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA
| | | | | | | | | |
Collapse
|
26
|
Sutter B, Bounds PL, Koppenol WH. The preparation of apo-Cu,Zn superoxide dismutase by ion-exchange chromatography on iminodiacetic acid-sepharose. Protein Expr Purif 2000; 19:53-6. [PMID: 10833390 DOI: 10.1006/prep.2000.1241] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The superoxide dismutases (EC 1.15.1.1) are a family of enzymes that catalyze the dismutation of superoxide radical anion to dioxygen and hydrogen peroxide. The active site contains a critical metal ion such as manganese, iron, or copper. The copper-containing protein also has one zinc ion bound per subunit. The standard method used to remove the metal ions from Cu,Zn superoxide dismutase has been to exhaustively dialyze the protein against chelating agents at low pH. We have developed a new method where the protein is bound to ion-exchange medium based on iminodiacetic acid immobilized on Sepharose. The bound protein is treated with a buffer containing edta at pH 3.5 to remove metal ions; the buffer is then exchanged for acetate buffer to remove edta, after which the protein is eluted by a salt gradient. An advantage of this method is that a single chromatography step is sufficient to produce apo protein. Results are shown for both human and bovine dimeric Cu,Zn superoxide dismutase and the monomeric Escherichia coli Cu,Zn superoxide dismutase. In every case, the metals were removed efficiently.
Collapse
Affiliation(s)
- B Sutter
- Laboratorium für Anorganische Chemie, Eidgenössische Technische Hochschule, Universitätstrasse 6, Zürich, CH-8092, Switzerland
| | | | | |
Collapse
|
27
|
Abstract
Dihydroorotase (DHOase, EC 3.5.2.3) is a zinc enzyme that catalyzes the reversible cyclization of N-carbamyl-L-aspartate to L-dihydroorotate in the third reaction of the de novo pathway for biosynthesis of pyrimidine nucleotides. The recombinant hamster DHOase domain from the trifunctional protein, CAD, was overexpressed in Escherichia coli and purified. The DHOase domain contained one bound zinc atom at the active site which was removed by dialysis against the chelator, pyridine-2,6-dicarboxylate, at pH 6.0. The apoenzyme was reconstituted with different divalent cations at pH 7.4. Co(II)-, Zn(II)-, Mn(II)-, and Cd(II)-substituted DHOases had enzymic activity, but replacement with Ni(2+), Cu(2+), Mg(2+), or Ca(2+) ions did not restore activity. Atomic absorption spectroscopy showed binding of one Co(II), Zn(II), Mn(II), Cd(II), Ni(II), or Cu(II) to the enzyme, while Mg(II) and Ca(II) were not bound. The maximal enzymic activities of the active, reconstituted DHOases were in the following order: Co(II) --> Zn(II) --> Mn(II) --> Cd(II). These metal substitutions had major effects upon values for V(max); effects upon the corresponding K(m) values were less pronounced. The pK(a) values of the Co(II)-, Mn(II)-, and Cd(II)-substituted enzymes derived from pH-rate profiles are similar to that of Zn(II)-DHOase, indicating that the derived pK(a) value of 6.56 obtained for Zn-DHOase is not due to ionization of an enzyme-metal aquo complex, but probably a histidine residue at the active site. The visible spectrum of Co(II)-substituted DHOase exhibits maxima at 520 and 570 nm with molar extinction coefficients of 195 and 210 M(-1) cm(-1), consistent with pentacoordination of Co(II) at the active site. The spectra at high and low pH are different, suggesting that the environment of the metal binding site is different at these pHs where the reverse and forward reactions, respectively, are favored.
Collapse
Affiliation(s)
- D T Huang
- Department of Biochemistry, University of Sydney, Sydney, New South Wales 2006, Australia
| | | | | |
Collapse
|
28
|
Tripatara A, Korotchkina LG, Patel MS. Characterization of point mutations in patients with pyruvate dehydrogenase deficiency: role of methionine-181, proline-188, and arginine-349 in the alpha subunit. Arch Biochem Biophys 1999; 367:39-50. [PMID: 10375397 DOI: 10.1006/abbi.1999.1231] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human pyruvate dehydrogenase (E1), a heterotetramer (alpha2beta2), is the first component of the pyruvate dehydrogenase complex (PDC). E1 catalyzes the thiamin pyrophosphate (TPP)-dependent decarboxylation of pyruvate and the reductive acetylation of the dihydrolipoamide acetyltransferase component. Site-directed mutagenesis was employed to recreate three point mutations in the alpha subunit identified in E1-deficient patients, M181V, R349H, and P188L (P188A mutant E1 was used because of the very low level of expression of P188L), to investigate the functional roles of these three amino acid residues. P188A mutant E1 was much less thermostable than the wild-type E1. The kcats of M181V and P188A mutant E1s determined in the PDC reaction were 38 and 24% of that of the wild-type enzyme, respectively. The apparent Km for TPP for M181V increased significantly (approx 250-fold when determined in the PDC assay), while the apparent Km for pyruvate increased by only about 3-fold. In contrast, P188A had similar Kms for the coenzyme and the substrate as the wild-type. Km values for R349H were not determined due to the extremely low activity of this mutant (1.2% of the wild-type E1-specific activity measured in the PDC assay). Wild-type E1 displayed a lag phase in the progress curve of the PDC reaction measured in the presence of low TPP concentrations (below 1 microM) only. All mutants had a lag phase that was not eliminated even at very high TPP concentrations, suggesting modifications in the conformation of the active site. Kinetic analysis indicated thiamin 2-thiothiazolone pyrophosphate (ThTTPP) to be an intermediate analog for wild-type human E1. M181V required a higher concentration of ThTTPP for inactivation than the wild-type and P188A E1s. The results of circular dichroism spectropolarimetry in the far UV region indicated that there were no major changes in the secondary structure of M181V, P188A, and R349H E1s. These mutant enzymes exhibited negative dichroic spectra at about 330 nm only in the presence of high TPP concentrations. This study suggests that arginine-349 is critical for E1's activity, methionine-181 is involved in the binding of TPP, and proline-188 is necessary for structural integrity of E1.
Collapse
Affiliation(s)
- A Tripatara
- School of Medicine and Biomedical Sciences, State University of New York at Buffalo, New York, 14214, USA
| | | | | |
Collapse
|
29
|
Cozier GE, Salleh RA, Anthony C. Characterization of the membrane quinoprotein glucose dehydrogenase from Escherichia coli and characterization of a site-directed mutant in which histidine-262 has been changed to tyrosine. Biochem J 1999; 340 ( Pt 3):639-47. [PMID: 10359647 PMCID: PMC1220294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The requirements for substrate binding in the quinoprotein glucose dehydrogenase (GDH) in the membranes of Escherichia coli are described, together with the changes in activity in a site-directed mutant in which His262 has been altered to a tyrosine residue (H262Y-GDH). The differences in catalytic efficiency between substrates are mainly related to differences in their affinity for the enzyme. Remarkably, it appears that, if a hexose is able to bind in the active site, then it is also oxidized, whereas some pentoses are able to bind (and act as competitive inhibitors), but are not substrates. The activation energies for the oxidation of hexoses and pentoses are almost identical. In a previously published model of the enzyme, His262 is at the entrance to the active site and appears to be important in holding the prosthetic group pyrroloquinoline quinone (PQQ) in place, and it has been suggested that it might play a role in electron transfer from the reduced PQQ to the ubiquinone in the membrane. The H262Y-GDH has a greatly diminished catalytic efficiency for all substrates, which is mainly due to a marked decrease in their affinities for the enzyme, but the rate of electron transfer to oxygen is unaffected. During the processing of the PQQ into the apoenzyme to give active enzyme, its affinity is markedly dependent on the pH, four groups with pK values between pH7 and pH8 being involved. Identical results were obtained with H262Y-GDH, showing that His262 it is not directly involved in this process.
Collapse
Affiliation(s)
- G E Cozier
- Division of Biochemistry and Molecular Biology, School of Biological Sciences, University of Southampton, Southampton SO16 7PX, UK
| | | | | |
Collapse
|
30
|
Tedeschi G, Negri A, Ceciliani F, Mattevi A, Ronchi S. Structural characterization of l-aspartate oxidase and identification of an interdomain loop by limited proteolysis. Eur J Biochem 1999; 260:896-903. [PMID: 10103021 DOI: 10.1046/j.1432-1327.1999.00234.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
l-Aspartate oxidase is the first enzyme in the de novo biosynthesis of pyridinic coenzymes in facultative aerobic organisms. The enzyme is FAD dependent and it shares common features with both the oxidase and the fumarate reductase classes of flavoproteins. In this report we focused our attention on the supersecondary structure of the molecule by means of limited proteolysis studies. Moreover the polymerization state of the protein at different pH and the interactions with NAD and its analogues are described. The results suggest that l-aspartate oxidase is a monomer at pH values lower than 4.5 and a dimer at pH values higher than 6.5. The protein is organized in two major domains connected by a flexible loop located in the 120-140 region. The data obtained by limited proteolysis of the holo and the apo form in the presence and in the absence of substrates (fumarate and menadione), inhibitors (succinate) and NAD allows the proposition that both domains are involved in the binding of the flavin coenzyme. Moreover the data reported in this manuscript suggest that NAD inhibits l-aspartate oxidase activity by competing with the flavin for the binding to the enzyme.
Collapse
Affiliation(s)
- G Tedeschi
- Istituto di Fisiologia Veterinaria e Biochimica, Università di Milano, Italy
| | | | | | | | | |
Collapse
|
31
|
Saint-Jean AP, Phillips KR, Creighton DJ, Stone MJ. Active monomeric and dimeric forms of Pseudomonas putida glyoxalase I: evidence for 3D domain swapping. Biochemistry 1998; 37:10345-53. [PMID: 9671502 DOI: 10.1021/bi980868q] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
3D domain swapping of proteins involves the interconversion of a monomer containing a single domain-domain interface and a 2-fold symmetrical dimer containing two equivalent intermolecular interfaces. Human glyoxalase I has the structure of a domain-swapped dimer [Cameron, A. D., Olin, B., Ridderström, M., Mannervik, B., and Jones, T. A. (1997) EMBO J. 16, 3386-3395] but Pseudomonas putida glyoxalase I has been reported to be monomeric [Rhee, H.-I., Murata, K., and Kimura, A. (1986) Biochem. Biophys. Res. Commun. 141, 993-999]. We show here that recombinant P. putida glyoxalase I is an active dimer (kcat approximately 500 +/- 100 s-1; KM approximately 0.4 +/- 0.2 mM) with two zinc ions per dimer. The zinc is required for structure and function. However, treatment of the dimer with glutathione yields an active monomer (kcat approximately 115 +/- 40 s-1; KM approximately 1.4 +/- 0.4 mM) containing a single zinc ion. The monomer is metastable and slowly reverts to the active dimer in the absence of glutathione. Thus, glyoxalase I appears to be a novel example of a single protein able to exist in two alternative domain-swapped forms. It is unique among domain-swapped proteins in that the active site and an essential metal binding site are apparently disassembled and reassembled by the process of domain swapping. Furthermore, it is the only example to date in which 3D domain swapping can be regulated by a small organic ligand.
Collapse
Affiliation(s)
- A P Saint-Jean
- Department of Chemistry, Indiana University, Bloomington 47405-0001, USA
| | | | | | | |
Collapse
|
32
|
Oakley AJ, Lo Bello M, Ricci G, Federici G, Parker MW. Evidence for an induced-fit mechanism operating in pi class glutathione transferases. Biochemistry 1998; 37:9912-7. [PMID: 9665696 DOI: 10.1021/bi980323w] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Three-dimensional structures of the apo form of human pi class glutathione transferase have been determined by X-ray crystallography. The structures suggest the enzyme recognizes its substrate, glutathione, by an induced-fit mechanism. Compared to complexed forms of the enzyme, the environment around the catalytic residue, Tyr 7, remains unchanged in the apoenzyme. This observation supports the view that Tyr 7 does not act as a general base in the reaction mechanism. The observed cooperativity of the dimeric enzyme may be due to the movements of a helix that forms one wall of the active site and, in particular, to movements of a tyrosine residue that is located in the subunit interface.
Collapse
Affiliation(s)
- A J Oakley
- The Ian Potter Foundation Protein Crystallography Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
| | | | | | | | | |
Collapse
|
33
|
Dewanti AR, Duine JA. Reconstitution of membrane-integrated quinoprotein glucose dehydrogenase apoenzyme with PQQ and the holoenzyme's mechanism of action. Biochemistry 1998; 37:6810-8. [PMID: 9578566 DOI: 10.1021/bi9722610] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Membrane-integrated quinoprotein glucose dehydrogenase from Acinetobacter calcoaceticus was produced by heterologous expression of the gene for it in an Escherichia coli recombinant strain. The apoenzyme (lacking the cofactor pyrroloquinoline quinone, PQQ) was solubilized with Triton X-100 and purified to homogeneity. Reconstitution of the apoenzyme to full activity in the assay was achieved with a stoichiometric amount of PQQ in the presence of Mg2+. Just as for other PQQ-containing dehydrogenases where Ca2+ fulfills this role, Mg2+ anchors PQQ to the mGDH protein and activates the bound cofactor. This occurs in a precise way since high anomer specificity was found for the enzyme toward the sugars tested. Although the steady-state-type kinetics were as expected for a dye-linked dehydrogenase (ping-pong) and the PQQ in it was present in oxidized form, addition of glucose to the holoenzyme resulted in a very slow but continuous production of gluconolactone; i.e., the reaction did not stop after one turnover, with O2 apparently acting as an (albeit poor) electron acceptor by reoxidizing PQQH2 in the enzyme. The surprisingly low reactivity with glucose, in the absence of dye, as compared to the activity observed in the steady-state assay appeared to be due to formation of an anomalous enzyme form, mGDH. Formation of normal holoenzyme, mGDH, reducing added glucose immediately to gluconolactone (in one turnover), was achieved by treating mGDH with sulfite, by reconstituting apoenzyme with PQQ in the presence of sulfite, or by applying assay conditions to mGDH (addition of PMS/DCPIP). As compared to other quinoprotein dehydrogenases, mGDH appears to be unique with respect to the mode of PQQ-binding, as expressed by the special conditions for reconstitution and the absorption spectra of the bound cofactor, and the reactivity of the reduced enzyme toward O2. The primary cause for this seems not to be related to a different preference for the activating bivalent metal ion but to the special way of binding of PQQ to mGDH.
Collapse
Affiliation(s)
- A R Dewanti
- Department of Microbiology and Enzymology, Delft University of Technology, The Netherlands
| | | |
Collapse
|
34
|
Awan SJ, Siligardi G, Shoolingin-Jordan PM, Warren MJ. Reconstitution of the holoenzyme form of Escherichia coli porphobilinogen deaminase from apoenzyme with porphobilinogen and preuroporphyrinogen: a study using circular dichroism spectroscopy. Biochemistry 1997; 36:9273-82. [PMID: 9230062 DOI: 10.1021/bi9702602] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Porphobilinogen deaminase (PBG-D), an early enzyme of the tetrapyrrole biosynthetic pathway, catalyzes the formation of a tetrapyrrole chain, preuroporphyrinogen, from four molecules of porphobilinogen (PBG). The PBG-D apoenzyme is responsible for the autocatalytic synthesis and covalent attachment of a dipyrromethane cofactor at its active site. In this paper an efficient method for the purification of Escherichia coli PBG-D apoenzyme using an affinity chromatography resin is reported. Circular dichroism (CD) spectra of apoenzyme and holoenzyme were recorded and significant differences in both the backbone and aromatic region of the spectra were observed. The differences in the spectra allowed the reconstitution of holoenzyme from purified apoenzyme with PBG and preuroporphyrinogen in solution to be monitored separately by CD. Apoenzyme incubated with preuroporhyrinogen gave a CD spectrum that was much more like the CD spectrum of holoenzyme than apoenzyme incubated with PBG. The results showed clearly that the cofactor was generated much more rapidly from preuroporphyrinogen than from PBG. Changes in the CD spectrum associated with the aromatic side-chain region, in particular the contribution assigned to phenylalanine-62, were found to correlate well with the activity of the reconstituted enzyme. Phenylalanine-62 is located in close proximity to the cofactor and acts as a sensitive probe to active-site changes. The stability of the holoenzyme and apoenzyme were compared with respect to both heat and susceptibility to proteolysis. The results were consistent with a model for the apoenzyme in which, in the absence of the cofactor, the three domains of the protein are held less rigidly together, thereby making the protein more susceptible to heat denaturation and proteolysis. The CD spectrum of the holoenzyme was found to be similar at both pH 5.1 and 7.4, suggesting that the crystal structure, determined at pH 5.1, is likely to be similar at physiological pH values.
Collapse
Affiliation(s)
- S J Awan
- Department of Molecular Genetics, Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, England
| | | | | | | |
Collapse
|
35
|
Abstract
Tryptic digestion of apo-soybean peroxidase (apo-SBP), with and without acetamidation, chromatographic separation of the tryptic fragments and MALDI-TOF analysis of the major components, both before and after digestion with glycopeptidase A, demonstrated the presence of six carbohydrate groups on five peptides. Five of the glycopeptides can be mapped with confidence to the peptides containing Asn16, Asn90, Asn104, Asn169, and Asn174. The sixth N-glycosylation site is not known and does not appear to be Asn145. It may be present on the N-terminus of SBP, which has not been sequenced.
Collapse
Affiliation(s)
- J S Gray
- Department of Biochemistry, College of Medicine, University of Iowa, Iowa City 52242, USA
| | | |
Collapse
|
36
|
Pinto AL, Hellinga HW, Caradonna JP. Construction of a catalytically active iron superoxide dismutase by rational protein design. Proc Natl Acad Sci U S A 1997; 94:5562-7. [PMID: 9159112 PMCID: PMC20818 DOI: 10.1073/pnas.94.11.5562] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/1996] [Accepted: 03/18/1997] [Indexed: 02/04/2023] Open
Abstract
The rational protein design algorithm DEZYMER was used to introduce the active site of nonheme iron superoxide dismutase (SOD) into the hydrophobic interior of the host protein, Escherichia coli thioredoxin (Trx), a protein that does not naturally contain a transition metal-binding site. Reconstitution of the designed protein, Trx-SOD, showed the incorporation of one high-affinity metal-binding site. The electronic spectra of the holoprotein and its N3- and F- adducts are analogous to those previously reported for native {Fe3+}SOD. Activity assays showed that {Fe3+}Trx-SOD is capable of catalyzing the dismutation of the superoxide anion; comparative studies with the unrelated wild-type E. coli iron SOD indicated that {Fe3+}Trx-SOD catalyzes the dismutation reaction at a rate on the order of 10(5) M-1s -1. The ability to design catalytically competent metalloenzymes allows for the systematic investigation of fundamental mechanistic questions concerning catalysis at transition metal centers.
Collapse
Affiliation(s)
- A L Pinto
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107, USA
| | | | | |
Collapse
|
37
|
Bernat BA, Laughlin LT, Armstrong RN. Fosfomycin resistance protein (FosA) is a manganese metalloglutathione transferase related to glyoxalase I and the extradiol dioxygenases. Biochemistry 1997; 36:3050-5. [PMID: 9115979 DOI: 10.1021/bi963172a] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The enzyme conferring resistance to the antibiotic fosfomycin [(1R,2S)-1,2-epoxypropylphosphonic acid] originally reported by Suarez and co-workers [Area, P., Hardisson, C., & Suarez, J. E. (1990) Antimicrob. Agents Chemother. 34, 844-848] is demonstrated in this study to be a metalloglutathione transferase. The apoenzyme is a dimer of 16 kDa subunits. Electron paramagnetic resonance spectroscopy and water proton nuclear magnetic resonance longitudinal relaxation rates suggest that each subunit contains a mononuclear Mn2+ center that interacts strongly with the substrate fosfomycin (Kd = 17 microM) more weakly with the product (Kd = 1.1 mM) and very weakly or not at all with GSH. Inhomogeneous broadening of the EPR signals of enzyme-bound Mn2+ in the presence of H2(17)O indicates that three of the coordination sites on the metal are occupied by water. Sequence alignments, three-dimensional structures, and mechanistic considerations suggest that FosA is related to at least two other metalloenzymes, glyoxalase I and the Mn2+- or Fe2+-containing extradiol dioxygenases. The mechanistic imperative driving the evolution of this previously unidentified superfamily of metalloenzymes is proposed to be bidentate coordination of a substrate or intermediate to the metal center in the enzyme-catalyzed reactions.
Collapse
Affiliation(s)
- B A Bernat
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
| | | | | |
Collapse
|
38
|
Rob A, Ball AS, Tuncer M, Wilson MT. Catalytic mechanism of the novel non-haem iron containing peroxidase produced by the thermophilic actinomycete Thermomonospora fusca BD25. Biochem Soc Trans 1997; 25:64S. [PMID: 9056962 DOI: 10.1042/bst025064s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- A Rob
- Department of Biological and Chemical Sciences, University of Essex, Colchester, United Kingdom
| | | | | | | |
Collapse
|
39
|
Shoolingin-Jordan PM, Warren MJ, Awan SJ. Dipyrromethane cofactor assembly of porphobilinogen deaminase: formation of apoenzyme and preparation of holoenzyme. Methods Enzymol 1997; 281:317-27. [PMID: 9250996 DOI: 10.1016/s0076-6879(97)81038-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- P M Shoolingin-Jordan
- Department of Biochemistry, School of Biological Science, University of Southampton, United Kingdom
| | | | | |
Collapse
|
40
|
Abstract
Two unique isozymes of superoxide dismutase (EC 1.15.1.1) were purified to apparent homogeneity from Streptomyces griseus by a purification procedure consisting of ammonium sulfate precipitation and chromatographies on DEAE Sephacel, Sephacryl S-200, and DEAE 5PW. Superoxide dismutase I was composed of four identical subunits of 13.0 kDa. The absorption spectrum of superoxide dismutase I exhibited absorption bands at 276 and 378 nm and a broad shoulder at 530 nm. The g values of electron paramagnetic resonance spectrum of superoxide dismutase I were g1 = 2.304, g2 = 2.248, and g3 = 2.012 and the resonance centered at g3 = 2.012 was split into triplet, indicating nickel-containing superoxide dismutase. Superoxide dismutase I contained 0.89 g-atom of nickel per mole of 13.0-kDa subunit. Superoxide dismutase II was composed of four identical subunits of 22.0 kDa. The absorption spectrum of superoxide dismutase II showed the featureless absorption band in the range of 300-500 nm. The g values of electron paramagnetic resonance spectrum of superoxide dismutase II were gz = 4.762, gx = 4.072, and gy = 3.742, indicating iron-containing superoxide dismutase. Superoxide dismutase II uniquely contains 0.40 g-atom of iron per mole of monomer as well as 0.43 g-atom of zinc per mole of monomer. The immunological cross-reactivity between two isozymes was not found. Nickel-containing superoxide dismutase was widely distributed within the genus Streptomyces; however, iron- and zinc-containing superoxide dismutase was not found in S. albus and S. longisporoflavus, on the basis of the immunological cross-reactivity.
Collapse
Affiliation(s)
- H D Youn
- Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea
| | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
After developing a rapid gel filtration method to prepare pure and stable apoenzyme forms of D-amino acid oxidase from the yeast Rhodotorula gracilis, we carried out comparative kinetic studies on the reconstitution to holoenzyme (with FAD) of the intact (40 kDa) and proteolyzed (38.3 kDa) apoenzyme forms of this oxidase. Changes in catalytic activity and flavin and protein fluorescence revealed that in both cases reconstitution was biphasic. The proteolyzed enzyme was catalytically competent, but unlike the intact form was unable to dimerize following formation of the apoprotein-FAD complex. We present evidence that reconstitution of holoenzyme from apoenzyme plus FAD does not involve dimerization, and that dimerization is not necessary for expression of DAAO activity. We propose that both apoenzyme forms share a common reconstitution mechanism, which includes a step of conformational interconversion of an enzymatically active intermediate to the final holoenzyme.
Collapse
|
42
|
Raibekas AA, Massey V. Glycerol-induced development of catalytically active conformation of Crotalus adamanteus L-amino acid oxidase in vitro. Proc Natl Acad Sci U S A 1996; 93:7546-51. [PMID: 8755511 PMCID: PMC38782 DOI: 10.1073/pnas.93.15.7546] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The reconstitutable apoprotein of Crotalus adamanteus L-amino acid oxidase was prepared using hydrophobic interaction chromatography. After reconstitution with flavin adenine dinucleotide, the resulting protein was inactive, with a perturbed conformation of the flavin binding site. Subsequently, a series of cosolvent-dependent compact intermediates was identified. The nearly complete activation of the reconstituted apoprotein and the restoration of its native flavin binding site was achieved in the presence of 50% glycerol. We provide evidence that in addition to a merely stabilizing effect of glycerol on native proteins, glycerol can also have a restorative effect on their compact equilibrium intermediates, and we suggest the hydrophobic effect as a dominating force in this in vitro-assisted restorative process.
Collapse
Affiliation(s)
- A A Raibekas
- Department of Biological Chemistry, The University of Michigan Medical School, Ann Arbor 48109-0606, USA
| | | |
Collapse
|
43
|
Dalton DA, Diaz del Castillo L, Kahn ML, Joyner SL, Chatfield JM. Heterologous expression and characterization of soybean cytosolic ascorbate peroxidase. Arch Biochem Biophys 1996; 328:1-8. [PMID: 8638916 DOI: 10.1006/abbi.1996.0135] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Ascorbate peroxidase is a widespread plant enzyme that catalyzes the removal of potentially harmful H2O2. This enzyme is particularly important in legume root nodules due to their high potential for generating activated forms of oxygen. A cDNA clone of soybean nodule ascorbate peroxidase was used to construct an expression system in Escherichia coli. The recombinant protein had an N-terminal tag of six consecutive histidine residues to allow for purification by Ni(2+)-agarose affinity chromatography. Large amounts of recombinant peroxidase (about 27% of total soluble protein) were produced but most of the peroxidase was present in the apo-form (without heme). Addition of delta-aminolevulinic acid to the growth media resulted in an increase in production of holoprotein. Apoprotein was easily converted to the holo-form by in vitro reconstitution with hemin. The reconstituted protein was catalytically, spectrally, and immunologically indistinguishable from native ascorbate peroxidase.
Collapse
Affiliation(s)
- D A Dalton
- Biology Department, Reed College, Portland, Oregon 97202, USA
| | | | | | | | | |
Collapse
|
44
|
Pollegioni L, Ceciliani F, Curti B, Ronchi S, Pilone MS. Studies on the structural and functional aspects of Rhodotorula gracilis D-amino acid oxidase by limited trypsinolysis. Biochem J 1995; 310 ( Pt 2):577-83. [PMID: 7654197 PMCID: PMC1135934 DOI: 10.1042/bj3100577] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The structure-function relationships of purified Rhodotorula gracilis D-amino acid oxidase (in its holo-, apo- and holo-enzyme-benzoate complex forms) was analysed by digestion with trypsin. In all cases trypsin cleaves this 80 kDa dimeric enzyme at the C-terminal region, since the peptide bonds sensitive to proteinase attack are clustered in this region. Digestion of native enzyme with trypsin produced a nicked and truncated form of 38.3 kDa containing two polypeptides of 34 and 5 kDa starting from Met1 and Ala319 respectively, and with detachment of the Thr306-Arg318 and Glu365-Leu368 peptides. Our results show that this 'core', folded into a compact structure, is catalytically competent. The acquisition of this nicked form was marked by a shift from a dimeric to a monomeric active enzyme, a result never previously obtained. The deleted sequences, Thr306-Arg318 and Glu365-Leu368, are essential for the monomer-monomer interaction, and, in particular, the region encompassing Thr306-Arg318 should play an essential role in the dimerization process. interestingly, the Ser308-Lys321 sequence present in the lost peptide corresponds to a sequence not present in other known D-amino acid oxidases [Faotto, Pollegioni, Ceciliani, Ronchi and Pilone (1995) Biotechnol. Lett. 17, 193-198]. A role of the cleaved-off region for the thermostabilization of the enzyme is also discussed.
Collapse
Affiliation(s)
- L Pollegioni
- Centro Interuniversitario per lo Studio delle Macromolecole Informazionali, University of Milano, Italy
| | | | | | | | | |
Collapse
|
45
|
Michaud-Soret I, Andersson KK, Que L, Haavik J. Resonance Raman studies of catecholate and phenolate complexes of recombinant human tyrosine hydroxylase. Biochemistry 1995; 34:5504-10. [PMID: 7727409 DOI: 10.1021/bi00016a022] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Human tyrosine hydroxylase isoform 1 (hTH1) was expressed in Escherichia coli, purified as the apoenzyme, and reconstituted with iron. The resonance Raman spectra of hTH1 complexed with dopamine, noradrenaline, tyramine, and catechol have been studied and compared to those obtained for TH isolated from bovine adrenal glands or rat phaeochromocytoma tissue. A TH-phenolate complex is reported for the first time. Using dopamine selectively 18O-labeled in the 3-position or both 3- and 4-hydroxy positions, we have been able to assign unambiguously the origin of the low-frequency vibration bands: the band at 631 cm-1 involves the oxygen in the 4-position; the band at 592 cm-1 involves the oxygen in the 3-position, and the band around 528 cm-1 is shifted by both, suggesting a chelated mode vibration. A small shift of the 1275 cm-1 band and no shift of the 1320 cm-1 band were observed, showing that those two bands involve essentially ring vibrations of the catecholate moiety, rather than the C--O stretching vibration as previously suggested. The spectrum of the catechol-d6-hTH1 complex confirms this assignment. The resonance Raman spectra of the 54Fe, 56Fe, or 57Fe isotope-containing enzymes complexed with dopamine are virtually identical, showing that the component of the iron in the approximately 600 cm-1 vibrations is too small to be observed. These results provide a better understanding of the Raman properties of iron-catecholate complexes in this enzyme, as well as in other metalloproteins and model compounds.
Collapse
Affiliation(s)
- I Michaud-Soret
- Department of Chemistry, University of Minnesota, Minneapolis 55455, USA
| | | | | | | |
Collapse
|
46
|
Hawkes TR, Thomas PG, Edwards LS, Rayner SJ, Wilkinson KW, Rice DW. Purification and characterization of the imidazoleglycerol-phosphate dehydratase of Saccharomyces cerevisiae from recombinant Escherichia coli. Biochem J 1995; 306 ( Pt 2):385-97. [PMID: 7887893 PMCID: PMC1136533 DOI: 10.1042/bj3060385] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The HIS3+ gene of Saccharomyces cerevisiae was overexpressed in Escherichia coli and the recombinant imidazoleglycerol-phosphate dehydratase (IGPD) purified to homogeneity. Laser-desorption and electrospray m.s. indicated a molecular ion within 2 units of that expected (23833.3) on the basis of the protein sequence, with about half of the polypeptide lacking the N-terminal formylmethionine residue. IGPD initially purified as an apoprotein was catalytically inactive and mainly a trimer of M(r) 70,000. Addition of Mn2+ (but not Mg2+) caused this to assemble to an active (40 units/mg) enzyme (Mn-IGPD) comprising of 24 subunits (M(r) 573,000) and containing 1.35 +/- 0.1 Mn atoms/polypeptide subunit. An enzyme with an identical activity and metal content was also obtained when the fermenter growth medium of recombinant Escherichia coli was supplemented with MnCl2, and IGPD was purified through as Mn-IGPD rather than as the apoenzyme and assembled in vitro. Inhibition by EDTA indicated that the intrinsic Mn2+ was essential for activity. The retention of activity over time after dilution to very low concentrations of enzyme (< 20 nM) indicated that the metal remained in tight association with the protein. A novel continuous assay method was developed to facilitate the kinetic characterization of Mn-IGPD. At pH 7.0, the Km for IGP was 0.10 +/- 0.02 mM and the Ki value for inhibition by 1,2,4-triazole, 0.12 +/- 0.02 mM. In contrast with other reports, thiols had no influence on catalytic activity. The activity of Mn-IGPD varied with enzyme concentration in such a way as to suggest that it dissociates to a less active form at very low concentrations. Significant inhibition by the product, imidazole acetol phosphate, was inferred from the shape of the progress curve. Titration with, the potent competitive inhibitor, 2-hydroxy-3-(1,2,4-triazol-1-yl)propyl phosphonate indicated that Mn-IGPD contained 0.9 +/- 0.1 catalytic sites/protomer. The activity nearly doubled in the presence of high concentrations of Mn2+; the apparent Ks for stimulation was 20 microM. The basis of this effect was obscure, since there was no corresponding increase in the titre of active sites. Neither was there a discernable shift in the values of Km or Ki (above), although exogenous Mn2+ did reduce the optimum pH for kcat, from 7.2 to 6.8. On the basis of a single site/subunit, the maximum rate of catalytic turnover at 30 degrees C was 32 s-1.
Collapse
Affiliation(s)
- T R Hawkes
- Department of Exploratory Plant Sciences, Zeneca Agrochemicals, Bracknell, Berkshire, U.K
| | | | | | | | | | | |
Collapse
|
47
|
Affiliation(s)
- S T Kim
- Department of Biochemistry, University of North Carolina at Chapel Hill 27599, USA
| | | | | |
Collapse
|
48
|
Nishimura K, Ito J, Yoshimura T, Esaki N, Soda K. A simple method for determination of stereospecificity of aminotransferases for C-4' hydrogen transfer of the coenzyme. Bioorg Med Chem 1994; 2:605-7. [PMID: 7858965 DOI: 10.1016/0968-0896(94)85007-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A simple method was established for determination of the stereospecificity of C-4' hydrogen transfer of the coenzymes (pyridoxal and pyridoxamine). The method is based on the findings that aspartate aminotransferase of pig heart and D-amino acid aminotransferase of Bacillus sp. YM-1 catalyze the abstraction of the pro-S and pro-R proton at C-4' of pyridoxamine, respectively. Pyridoxal is a poor coenzyme, but readily released from the enzyme. It reacts in 3H2O with a substrate amino acid and an apo-aminotransferase whose stereospecificity for C-4' hydrogen transfer is to be determined. The resultant pyridoxamine which is tritiated at C-4' is incubated with an apo form of aspartate aminotransferase or D-amino acid aminotransferase and a substrate, alpha-keto acid. The stereospecificity for the C-4' hydrogen transfer examined is determined by measurement of radioactivity retained in the pyridoxal formed. We showed by means of this method that C-4' hydrogen transfer of coenzyme occurs on the si face of the external Schiff base in the transamination reactions of two aspartate aminotransferases of Bacillus sp. YM-2 and Escherichia coli, and aromatic amino acid aminotransferase of E. coli.
Collapse
Affiliation(s)
- K Nishimura
- Department of Applied Chemistry and Biotechnology, Yamanashi University, Japan
| | | | | | | | | |
Collapse
|
49
|
Madigan RA, Mayhew SG. Preparation of the apoenzyme of the FMN-dependent Clostridium kluyveri diaphorase by extraction with apoflavodoxin. Biochem Soc Trans 1994; 22:57S. [PMID: 8206286 DOI: 10.1042/bst022057s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- R A Madigan
- Department of Biochemistry, University College Dublin, Belfield, Ireland
| | | |
Collapse
|
50
|
Martínez A, Abeygunawardana C, Haavik J, Flatmark T, Mildvan AS. Conformation and interaction of phenylalanine with the divalent cation at the active site of human recombinant tyrosine hydroxylase as determined by proton NMR. Biochemistry 1993; 32:6381-90. [PMID: 8100148 DOI: 10.1021/bi00076a011] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recombinant human tyrosine hydroxylase has been purified as a metal-free apoenzyme (apo-hTH1) which tightly binds one Fe2+, Co2+, or Zn2+ per subunit with activation only by Fe2+ and competitive inhibition by the other cations. L-tyrosine and L-phenylalanine are alternative substrates for this enzyme, giving similar Vmax values, although the KM value for phenylalanine is about 8-fold greater than for tyrosine. Apo-hTH1 enhances the paramagnetic effects of Co2+ on 1/T1 and 1/T2 values of the protons of enzyme-bound phenylalanine both in the presence and in the absence of the oxidized form of the cofactor L-erythro-7,8-dihydrobiopterin (BH2), which was used as an inactive analog of the natural cofactor (6R)-1-erythro-tetrahydrobiopterin (BH4). No effects of hTH1-Zn2+ on 1/T1 or 1/T2 are found. From paramagnetic effects of hTH1-Co2+ on 1/T1 of phenylalanine protons at 250 and 600 MHz, in the presence of BH2, a correlation time (tau c) of 1.8 +/- 0.1 ps was found. Using this tau c value, and assuming that only one proton of the pairs H3,H5, and H2,H6 is experiencing the total paramagnetic effect (asymmetric limiting case), distances from enzyme-bound Co2+ to phenylalanine (+/- 1.2 A) of 6.1 A (H3 or H5), 6.3 A (H2 or H6), 7.0 A (H4), 7.3 A (H alpha), > or = 7.4 A (H beta-pro-S), and > or = 7.6 A (H beta-pro-R) were calculated. The distances to H3 or H5 and to H2 or H6 are slightly increased to 6.8 and 7.0 A, respectively, if each proton of both degenerate pairs equally experiences the paramagnetic effect of Co2+ (symmetric limiting case). These distances place the aromatic ring of phenylalanine in the second coordination sphere of the metal, which would permit an Fe-bound oxy or peroxy species to approach molecular contact with C3/C4, suggesting a direct role of Fe2+ in the hydroxylation reaction. The same correlation time and similar distances were found in the absence of BH2 with H4 of phenylalanine slightly closer to the metal. In the ternary hTH1-Zn(2+).BH2.phenylalanine complex, eight interproton distances in the enzyme-bound phenylalanine were determined by NOESY spectra at 600 MHz at 35-, 50-, and 75-ms mixing times. The conformation of enzyme-bound phenylalanine, consistent with the six Co(2+)-proton distances and the eight interproton distances, is partially extended with torsional angles chi 1 = 97 degrees +/- 3 degrees and chi 2 = -78 degrees +/- 2 degrees.
Collapse
Affiliation(s)
- A Martínez
- Department of Biochemistry, University of Bergen, Norway
| | | | | | | | | |
Collapse
|