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Vargas JA, Sculaccio SA, Pinto APA, Pereira HD, Mendes LFS, Flores JF, Cobos M, Castro JC, Garratt RC, Leonardo DA. Structural insights into the Smirnoff-Wheeler pathway for vitamin C production in the Amazon fruit camu-camu. J Exp Bot 2024; 75:2754-2771. [PMID: 38224521 DOI: 10.1093/jxb/erae016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 01/12/2024] [Indexed: 01/17/2024]
Abstract
l-Ascorbic acid (AsA, vitamin C) is a pivotal dietary nutrient with multifaceted importance in living organisms. In plants, the Smirnoff-Wheeler pathway is the primary route for AsA biosynthesis, and understanding the mechanistic details behind its component enzymes has implications for plant biology, nutritional science, and biotechnology. As part of an initiative to determine the structures of all six core enzymes of the pathway, the present study focuses on three of them in the model species Myrciaria dubia (camu-camu): GDP-d-mannose 3',5'-epimerase (GME), l-galactose dehydrogenase (l-GalDH), and l-galactono-1,4-lactone dehydrogenase (l-GalLDH). We provide insights into substrate and cofactor binding and the conformational changes they induce. The MdGME structure reveals a distorted substrate in the active site, pertinent to the catalytic mechanism. Mdl-GalDH shows that the way in which NAD+ association affects loop structure over the active site is not conserved when compared with its homologue in spinach. Finally, the structure of Mdl-GalLDH is described for the first time. This allows for the rationalization of previously identified residues which play important roles in the active site or in the formation of the covalent bond with FAD. In conclusion, this study enhances our understanding of AsA biosynthesis in plants, and the information provided should prove useful for biotechnological applications.
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Affiliation(s)
- Jhon A Vargas
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Susana A Sculaccio
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Andressa P A Pinto
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Humberto D'Muniz Pereira
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Luis F S Mendes
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Jhoao F Flores
- Institute of Biology, State University of Campinas, Rua Monteiro Lobato 255, Campinas, SP 13083-862, Brazil
| | - Marianela Cobos
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, 1600, Iquitos, Peru
- Departamento de Ciencias Biomédicas y Biotecnología, Facultad de Ciencias Biológicas, Universidad Nacional de la Amazonia Peruana (UNAP), Zungarococha, Ciudad Universitaria. Iquitos, Perú
| | - Juan C Castro
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, 1600, Iquitos, Peru
- Departamento de Ciencias Biomédicas y Biotecnología, Facultad de Ciencias Biológicas, Universidad Nacional de la Amazonia Peruana (UNAP), Zungarococha, Ciudad Universitaria. Iquitos, Perú
| | - Richard C Garratt
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Diego A Leonardo
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
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Pinto APA, Pereira HM, Zeraik AE, Ciol H, Ferreira FM, Brandão-Neto J, DeMarco R, Navarro MVAS, Risi C, Galkin VE, Garratt RC, Araujo APU. Filaments and fingers: Novel structural aspects of the single septin from Chlamydomonas reinhardtii. J Biol Chem 2017; 292:10899-10911. [PMID: 28476887 PMCID: PMC5491775 DOI: 10.1074/jbc.m116.762229] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [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: 10/06/2016] [Revised: 05/04/2017] [Indexed: 01/22/2023] Open
Abstract
Septins are filament-forming GTP-binding proteins involved in many essential cellular events related to cytoskeletal dynamics and maintenance. Septins can self-assemble into heterocomplexes, which polymerize into highly organized, cell membrane-interacting filaments. The number of septin genes varies among organisms, and although their structure and function have been thoroughly studied in opisthokonts (including animals and fungi), no structural studies have been reported for other organisms. This makes the single septin from Chlamydomonas (CrSEPT) a particularly attractive model for investigating whether functional homopolymeric septin filaments also exist. CrSEPT was detected at the base of the flagella in Chlamydomonas, suggesting that CrSEPT is involved in the formation of a membrane-diffusion barrier. Using transmission electron microscopy, we observed that recombinant CrSEPT forms long filaments with dimensions comparable with those of the canonical structure described for opisthokonts. The GTP-binding domain of CrSEPT purified as a nucleotide-free monomer that hydrolyzes GTP and readily binds its analog guanosine 5'-3-O-(thio)triphosphate. We also found that upon nucleotide binding, CrSEPT formed dimers that were stabilized by an interface involving the ligand (G-interface). Across this interface, one monomer supplied a catalytic arginine to the opposing subunit, greatly accelerating the rate of GTP hydrolysis. This is the first report of an arginine finger observed in a septin and suggests that CrSEPT may act as its own GTP-activating protein. The finger is conserved in all algal septin sequences, suggesting a possible correlation between the ability to form homopolymeric filaments and the accelerated rate of hydrolysis that it provides.
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Affiliation(s)
- Andressa P A Pinto
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil
- the Programa de Pós-graduação em Genética Evolutiva e Biologia Molecular, UFSCar, CEP 13565-905, São Carlos, SP, Brazil
| | - Humberto M Pereira
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil
| | - Ana E Zeraik
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil
| | - Heloisa Ciol
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil
| | | | - José Brandão-Neto
- the Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom, and
| | - Ricardo DeMarco
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil
| | - Marcos V A S Navarro
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil
| | - Cristina Risi
- the Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia 23501
| | - Vitold E Galkin
- the Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia 23501
| | - Richard C Garratt
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil,
| | - Ana P U Araujo
- From the Instituto de Física de São Carlos, Universidade de São Paulo, CEP: 13563-120, São Carlos, SP, Brazil,
- the Programa de Pós-graduação em Genética Evolutiva e Biologia Molecular, UFSCar, CEP 13565-905, São Carlos, SP, Brazil
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Dyszy F, Pinto APA, Araújo APU, Costa-Filho AJ. Probing the interaction of brain fatty acid binding protein (B-FABP) with model membranes. PLoS One 2013; 8:e60198. [PMID: 23555925 PMCID: PMC3610644 DOI: 10.1371/journal.pone.0060198] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [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: 11/13/2012] [Accepted: 02/21/2013] [Indexed: 12/11/2022] Open
Abstract
Brain fatty acid-binding protein (B-FABP) interacts with biological membranes and delivers polyunsaturated fatty acids (FAs) via a collisional mechanism. The binding of FAs in the protein and the interaction with membranes involve a motif called “portal region”, formed by two small α-helices, A1 and A2, connected by a loop. We used a combination of site-directed mutagenesis and electron spin resonance to probe the changes in the protein and in the membrane model induced by their interaction. Spin labeled B-FABP mutants and lipidic spin probes incorporated into a membrane model confirmed that B-FABP interacts with micelles through the portal region and led to structural changes in the protein as well in the micelles. These changes were greater in the presence of LPG when compared to the LPC models. ESR spectra of B-FABP labeled mutants showed the presence of two groups of residues that responded to the presence of micelles in opposite ways. In the presence of lysophospholipids, group I of residues, whose side chains point outwards from the contact region between the helices, had their mobility decreased in an environment of lower polarity when compared to the same residues in solution. The second group, composed by residues with side chains situated at the interface between the α-helices, experienced an increase in mobility in the presence of the model membranes. These modifications in the ESR spectra of B-FABP mutants are compatible with a less ordered structure of the portal region inner residues (group II) that is likely to facilitate the delivery of FAs to target membranes. On the other hand, residues in group I and micelle components have their mobilities decreased probably as a result of the formation of a collisional complex. Our results bring new insights for the understanding of the gating and delivery mechanisms of FABPs.
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Affiliation(s)
- Fábio Dyszy
- Grupo de Biofísica Molecular Sérgio Mascarenhas, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Sao Paulo, Brazil
| | - Andressa P. A. Pinto
- Grupo de Biofísica Molecular Sérgio Mascarenhas, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Sao Paulo, Brazil
| | - Ana P. U. Araújo
- Grupo de Biofísica Molecular Sérgio Mascarenhas, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Sao Paulo, Brazil
| | - Antonio J. Costa-Filho
- Grupo de Biofísica Molecular Sérgio Mascarenhas, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Sao Paulo, Brazil
- Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Sao Paulo, Brazil
- * E-mail:
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Zucolotto V, Pinto APA, Tumolo T, Moraes ML, Baptista MS, Riul A, Araújo APU, Oliveira ON. Catechol biosensing using a nanostructured layer-by-layer film containing Cl-catechol 1,2-dioxygenase. Biosens Bioelectron 2006; 21:1320-6. [PMID: 16054354 DOI: 10.1016/j.bios.2005.06.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Revised: 05/16/2005] [Accepted: 06/10/2005] [Indexed: 10/25/2022]
Abstract
The detection of aromatic compounds from pesticides and industrial wastewater has become of great interest, since these compounds withstand chemical oxidation and biological degradation, accumulating in the environment. In this work, a highly sensitive biosensor for detecting catechol was obtained with the immobilization of Cl-catechol 1,2-dioxygenase (CCD) in nanostructured films. CCD layers were alternated with poly(amidoamine) generation 4 (PAMAM G4) dendrimer using the electrostatic layer-by-layer (LbL) technique. Circular dichroism (CD) measurements indicated that the immobilized CCD preserved the same conformation as in solution. The thickness of the very first CCD layers in the LbL films was estimated at ca. 3.6 nm, as revealed by surface plasmon resonance (SPR). PAMAM/CCD 10-bilayer films were employed in detecting diluted catechol solutions using either an optical or electrical approach. Due to the mild immobilization conditions employed, especially regarding the pH and ionic strength of the dipping solutions, CCD remained active in the films for periods longer than 3 weeks. The optical detection comprised absorption experiments in which the formation of cis-cis muconic acid, resulting from the reaction between CCD and catechol, was monitored by measuring the absorbance at 260 nm after film immersion in catechol solutions. The electrical detection was carried out using LbL films deposited onto gold-interdigitated electrodes immersed in aqueous solutions at different catechol concentrations. Using impedance spectroscopy in a broad frequency range (1Hz-1kHz), we could detect catechol in solutions at concentrations as low as 10(-10) M.
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Affiliation(s)
- Valtencir Zucolotto
- Instituto de Física de São Carlos, USP, CP 369, 13560-970 So Carlos, SP, Brazil.
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Citadini APS, Pinto APA, Araújo APU, Nascimento OR, Costa-Filho AJ. EPR studies of chlorocatechol 1,2-dioxygenase: evidences of iron reduction during catalysis and of the binding of amphipatic molecules. Biophys J 2005; 88:3502-8. [PMID: 15722436 PMCID: PMC1305496 DOI: 10.1529/biophysj.104.055251] [Citation(s) in RCA: 22] [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: 11/18/2022] Open
Abstract
Chlorocatechol 1,2-dioxygenase from Pseudomonas putida (Pp 1,2-CCD) is a dioxygenase responsible for ring cleavage during the degradation of recalcitrant aromatic compounds. We determined the zero-field splitting of the Fe(III) cofactor (|D| = 1.3 +/- 0.2 cm(-1)) by electron paramagnetic resonance (EPR) experiments that along with other structural data allowed us to infer the Fe(III) coordination environment. The EPR spectrum of the ion shows a significantly decrease of the g = 4.3 resonance upon substrate binding. This result is rationalized in terms of a mechanism previously proposed, where catechol substrate is activated by Fe(III), yielding an exchange-coupled Fe(II)-semiquinone (pair). The Pp 1,2-CCD capacity of binding amphipatic molecules and the effects of such binding on protein activity are also investigated. EPR spectra of spin labels show a protein-bound component, which was characterized by means of spectral simulations. Our results indicate that Pp 1,2-CCD is able to bind amphipatic molecules in a channel with the headgroup pointing outwards into the solvent, whereas the carbon chain is held inside the tunnel. Protein assays show that the enzyme activity is significantly lowered in the presence of stearic-acid molecules. The role of the binding of those molecules as an enzyme activity modulator is discussed.
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Affiliation(s)
- Ana P S Citadini
- Instituto de Física de São Carlos, Departamento de Física e Informática, Universidade de São Paulo, São Carlos, SP, Brazil
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Pinto APA, Campana PT, Beltramini LM, Silber AM, Araújo APU. Structural characterization of a recombinant flagellar calcium-binding protein from Trypanosoma cruzi. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2003; 1652:107-14. [PMID: 14644046 DOI: 10.1016/j.bbapap.2003.08.008] [Citation(s) in RCA: 14] [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: 11/16/2022]
Abstract
Calflagin are flagellar calcium-binding proteins belonging to the EF-hand super family described in several protozoa, including Trypanosoma cruzi. Evidences have shown that Ca(2+) may play an important regulatory role in trypanosomatid flagellar mobility. In these parasites, the response of the cell to variations of Ca(2+) levels is determined by a variety of calcium-modulated proteins. Starting from T. cruzi cDNA lambdagt11 library trypomastigote, a clone encoding a 29-kDa flagellar protein designated recombinant calflagin (rC29) was selected. rC29 is a calcium-acyl switch protein modified by the addition of myristate and palmitate at its amino terminal segment. In this work, unmyristoylated rC29 was expressed in Escherichia coli as an intein fusion protein and purified by affinity chromatography. Circular dichroism (CD) and fluorescence measurements showed conformational changes of rC29 due to Ca(2+) binding. The Ca(2+) binding constants were obtained by tryptophan intrinsic fluorescence spectroscopy. Fluorescence titration exhibited two classes of Ca(2+)-binding sites in the unmyristoylated rC29, which bind calcium with apparent association constant of K(a) of 3.3+/-0.5 (10(6)) and 1.9+/-0.2 (10(4)) M(-1). Experiment using 8-anilinonaphthalene-1-sulfonic acid (ANS) as hydrophobic probe showed that the Ca(2+)-loaded form of rC29 contains exposed hydrophobic surfaces, thus suggesting that rC29 is probably functioning as a calcium sensor.
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Affiliation(s)
- Andressa P A Pinto
- Programa de Pós-graduação em Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luiz, km 235, São Carlos, São Paulo, Brazil
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