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Benchoam D, Cuevasanta E, Roman JV, Banerjee R, Alvarez B. Acidity of persulfides and its modulation by the protein environments in sulfide quinone oxidoreductase and thiosulfate sulfurtransferase. J Biol Chem 2024; 300:107149. [PMID: 38479599 PMCID: PMC11039317 DOI: 10.1016/j.jbc.2024.107149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 02/12/2024] [Accepted: 02/28/2024] [Indexed: 04/23/2024] Open
Abstract
Persulfides (RSSH/RSS-) participate in sulfur metabolism and are proposed to transduce hydrogen sulfide (H2S) signaling. Their biochemical properties are poorly understood. Herein, we studied the acidity and nucleophilicity of several low molecular weight persulfides using the alkylating agent, monobromobimane. The different persulfides presented similar pKa values (4.6-6.3) and pH-independent rate constants (3.2-9.0 × 103 M-1 s-1), indicating that the substituents in persulfides affect properties to a lesser extent than in thiols because of the larger distance to the outer sulfur. The persulfides had higher reactivity with monobromobimane than analogous thiols and putative thiols with the same pKa, providing evidence for the alpha effect (enhanced nucleophilicity by the presence of a contiguous atom with high electron density). Additionally, we investigated two enzymes from the human mitochondrial H2S oxidation pathway that form catalytic persulfide intermediates, sulfide quinone oxidoreductase and thiosulfate sulfurtransferase (TST, rhodanese). The pH dependence of the activities of both enzymes was measured using sulfite and/or cyanide as sulfur acceptors. The TST half-reactions were also studied by stopped-flow fluorescence spectroscopy. Both persulfidated enzymes relied on protonated groups for reaction with the acceptors. Persulfidated sulfide quinone oxidoreductase appeared to have a pKa of 7.8 ± 0.2. Persulfidated TST presented a pKa of 9.38 ± 0.04, probably due to a critical active site residue rather than the persulfide itself. The TST thiol reacted in the anionic state with thiosulfate, with an apparent pKa of 6.5 ± 0.1. Overall, our study contributes to a fundamental understanding of persulfide properties and their modulation by protein environments.
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Affiliation(s)
- Dayana Benchoam
- Laboratorio de Enzimología, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo, Uruguay; Graduate Program in Chemistry, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Ernesto Cuevasanta
- Laboratorio de Enzimología, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo, Uruguay; Unidad de Bioquímica Analítica, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Joseph V Roman
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Beatriz Alvarez
- Laboratorio de Enzimología, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo, Uruguay.
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Buonvino S, Arciero I, Melino S. Thiosulfate-Cyanide Sulfurtransferase a Mitochondrial Essential Enzyme: From Cell Metabolism to the Biotechnological Applications. Int J Mol Sci 2022; 23:ijms23158452. [PMID: 35955583 PMCID: PMC9369223 DOI: 10.3390/ijms23158452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 07/27/2022] [Accepted: 07/27/2022] [Indexed: 11/16/2022] Open
Abstract
Thiosulfate: cyanide sulfurtransferase (TST), also named rhodanese, is an enzyme widely distributed in both prokaryotes and eukaryotes, where it plays a relevant role in mitochondrial function. TST enzyme is involved in several biochemical processes such as: cyanide detoxification, the transport of sulfur and selenium in biologically available forms, the restoration of iron–sulfur clusters, redox system maintenance and the mitochondrial import of 5S rRNA. Recently, the relevance of TST in metabolic diseases, such as diabetes, has been highlighted, opening the way for research on important aspects of sulfur metabolism in diabetes. This review underlines the structural and functional characteristics of TST, describing the physiological role and biomedical and biotechnological applications of this essential enzyme.
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Biswas A, Ghosh S, Sinha D, Dutta A, Seal S, Bagchi A, Sau S. Dimerization ability, denaturation mechanism, and the stability of a staphylococcal phage repressor and its two domains. Int J Biol Macromol 2019; 124:903-914. [DOI: 10.1016/j.ijbiomac.2018.11.263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/27/2018] [Accepted: 11/27/2018] [Indexed: 11/29/2022]
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Hydrogen Sulfide Biochemistry and Interplay with Other Gaseous Mediators in Mammalian Physiology. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:6290931. [PMID: 30050658 PMCID: PMC6040266 DOI: 10.1155/2018/6290931] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/13/2018] [Indexed: 01/06/2023]
Abstract
Hydrogen sulfide (H2S) has emerged as a relevant signaling molecule in physiology, taking its seat as a bona fide gasotransmitter akin to nitric oxide (NO) and carbon monoxide (CO). After being merely regarded as a toxic poisonous molecule, it is now recognized that mammalian cells are equipped with sophisticated enzymatic systems for H2S production and breakdown. The signaling role of H2S is mainly related to its ability to modify different protein targets, particularly by promoting persulfidation of protein cysteine residues and by interacting with metal centers, mostly hemes. H2S has been shown to regulate a myriad of cellular processes with multiple physiological consequences. As such, dysfunctional H2S metabolism is increasingly implicated in different pathologies, from cardiovascular and neurodegenerative diseases to cancer. As a highly diffusible reactive species, the intra- and extracellular levels of H2S have to be kept under tight control and, accordingly, regulation of H2S metabolism occurs at different levels. Interestingly, even though H2S, NO, and CO have similar modes of action and parallel regulatory targets or precisely because of that, there is increasing evidence of a crosstalk between the three gasotransmitters. Herein are reviewed the biochemistry, metabolism, and signaling function of hydrogen sulfide, as well as its interplay with the other gasotransmitters, NO and CO.
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Eichmann C, Tzitzilonis C, Nakamura T, Kwiatkowski W, Maslennikov I, Choe S, Lipton SA, Riek R. S-Nitrosylation Induces Structural and Dynamical Changes in a Rhodanese Family Protein. J Mol Biol 2016; 428:3737-51. [PMID: 27473602 PMCID: PMC5260856 DOI: 10.1016/j.jmb.2016.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 06/15/2016] [Accepted: 07/12/2016] [Indexed: 01/07/2023]
Abstract
S-Nitrosylation is well established as an important post-translational regulator in protein function and signaling. However, relatively little is known about its structural and dynamical consequences. We have investigated the effects of S-nitrosylation on the rhodanese domain of the Escherichia coli integral membrane protein YgaP by NMR, X-ray crystallography, and mass spectrometry. The results show that the active cysteine in the rhodanese domain of YgaP is subjected to two competing modifications: S-nitrosylation and S-sulfhydration, which are naturally occurring in vivo. It has been observed that in addition to inhibition of the sulfur transfer activity, S-nitrosylation of the active site residue Cys63 causes an increase in slow motion and a displacement of helix 5 due to a weakening of the interaction between the active site and the helix dipole. These findings provide an example of how nitrosative stress can exert action at the atomic level.
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Affiliation(s)
- Cédric Eichmann
- Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - Christos Tzitzilonis
- Structural Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Tomohiro Nakamura
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, CA 92121, USA
| | - Witek Kwiatkowski
- Structural Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Innokentiy Maslennikov
- Structural Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Senyon Choe
- Structural Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Stuart A. Lipton
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, CA 92121, USA,Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA,Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Roland Riek
- Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zürich, Switzerland,Structural Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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6
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Huang GT, Yu JSK. Enzyme Catalysis that Paves the Way for S-Sulfhydration via Sulfur Atom Transfer. J Phys Chem B 2016; 120:4608-15. [DOI: 10.1021/acs.jpcb.6b03387] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Gou-Tao Huang
- Department of Biological Science and Technology and ‡Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu City 300, Taiwan
| | - Jen-Shiang K. Yu
- Department of Biological Science and Technology and ‡Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu City 300, Taiwan
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Libiad M, Sriraman A, Banerjee R. Polymorphic Variants of Human Rhodanese Exhibit Differences in Thermal Stability and Sulfur Transfer Kinetics. J Biol Chem 2015; 290:23579-88. [PMID: 26269602 DOI: 10.1074/jbc.m115.675694] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 11/06/2022] Open
Abstract
Rhodanese is a component of the mitochondrial H2S oxidation pathway. Rhodanese catalyzes the transfer of sulfane sulfur from glutathione persulfide (GSSH) to sulfite generating thiosulfate and from thiosulfate to cyanide generating thiocyanate. Two polymorphic variations have been identified in the rhodanese coding sequence in the French Caucasian population. The first, 306A→C, has an allelic frequency of 1% and results in an E102D substitution in the encoded protein. The second polymorphism, 853C→G, has an allelic frequency of 5% and leads to a P285A substitution. In this study, we have examined differences in the stability between wild-type rhodanese and the E102D and P285A variants and in the kinetics of the sulfur transfer reactions. The Asp-102 and Ala-285 variants are more stable than wild-type rhodanese and exhibit kcat/Km,CN values that are 17- and 1.6-fold higher, respectively. All three rhodanese forms preferentially catalyze sulfur transfer from GSSH to sulfite, generating thiosulfate and glutathione. The kcat/Km,sulfite values for the variants in the sulfur transfer reaction from GSSH to sulfite were 1.6- (Asp-102) and 4-fold (Ala-285) lower than for wild-type rhodanese, whereas the kcat/Km,GSSH values were similar for all three enzymes. Thiosulfate-dependent H2S production in murine liver lysate is low, consistent with a role for rhodanese in sulfide oxidation. Our studies show that polymorphic variations that are distant from the active site differentially modulate the sulfurtransferase activity of human rhodanese to cyanide versus sulfite and might be important in differences in susceptibility to diseases where rhodanese dysfunction has been implicated, e.g. inflammatory bowel diseases.
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Affiliation(s)
- Marouane Libiad
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
| | - Anusha Sriraman
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
| | - Ruma Banerjee
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
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8
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Raghunathan G, Soundrarajan N, Sokalingam S, Yun H, Lee SG. Deletional protein engineering based on stable fold. PLoS One 2012; 7:e51510. [PMID: 23240034 PMCID: PMC3519881 DOI: 10.1371/journal.pone.0051510] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 11/01/2012] [Indexed: 12/14/2022] Open
Abstract
Diversification of protein sequence-structure space is a major concern in protein engineering. Deletion mutagenesis can generate a protein sequence-structure space different from substitution mutagenesis mediated space, but it has not been widely used in protein engineering compared to substitution mutagenesis, because it causes a relatively huge range of structural perturbations of target proteins which often inactivates the proteins. In this study, we demonstrate that, using green fluorescent protein (GFP) as a model system, the drawback of the deletional protein engineering can be overcome by employing the protein structure with high stability. The systematic dissection of N-terminal, C-terminal and internal sequences of GFPs with two different stabilities showed that GFP with high stability (s-GFP), was more tolerant to the elimination of amino acids compared to a GFP with normal stability (n-GFP). The deletion studies of s-GFP enabled us to achieve three interesting variants viz. s-DL4, s-N14, and s-C225, which could not been obtained from n-GFP. The deletion of 191–196 loop sequences led to the variant s-DL4 that was expressed predominantly as insoluble form but mostly active. The s-N14 and s-C225 are the variants without the amino acid residues involving secondary structures around N- and C-terminals of GFP fold respectively, exhibiting comparable biophysical properties of the n-GFP. Structural analysis of the variants through computational modeling study gave a few structural insights that can explain the spectral properties of the variants. Our study suggests that the protein sequence-structure space of deletion mutants can be more efficiently explored by employing the protein structure with higher stability.
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Affiliation(s)
- Govindan Raghunathan
- Department of Chemical Engineering, Pusan National University, Busan, South Korea
| | | | - Sriram Sokalingam
- Department of Chemical Engineering, Pusan National University, Busan, South Korea
| | - Hyungdon Yun
- School of Biotechnology, Yeungnam University, Gyeongsan, South Korea
| | - Sun-Gu Lee
- Department of Chemical Engineering, Pusan National University, Busan, South Korea
- * E-mail:
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9
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Mukhopadhyay A, Yang CS, Wei B, Weiner H. Precursor protein is readily degraded in mitochondrial matrix space if the leader is not processed by mitochondrial processing peptidase. J Biol Chem 2007; 282:37266-75. [PMID: 17959599 DOI: 10.1074/jbc.m706594200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It is not known why leader peptides are removed by the mitochondrial processing peptidase after import into the matrix space. The leaders of yeast aldehyde dehydrogenase (pALDH) and malate dehydrogenase were mutated so that they would not be processed after import. The recombinant nonprocessed precursor of yeast pALDH possessed a similar specific activity as the corresponding mature form but was much less stable. The nonprocessed pALDH was transformed into a yeast strain missing ALDHs. The transformed yeast grew slowly on ethanol as the sole carbon source showing that the nonprocessed precursor was functional in vivo. Western blot analysis showed that the amount of precursor was 15-20% of that found in cells transformed with the native enzyme. Pulse-chase experiments revealed that the turnover rate for the nonprocessed precursor was greater than that of the mature protein indicating that the nonprocessed precursor could have been degraded. By using carbonyl cyanide m-chlorophenylhydrazone, we showed that the nonprocessed precursor was degraded in the matrix space. The nonprocessed precursor forms of precursor yeast malate dehydrogenase and rat liver pALDH also were degraded in the matrix space of HeLa cell mitochondria faster than their corresponding mature forms. In the presence of o-phenanthroline, an inhibitor of mitochondrial processing peptidase, the wild type precursor was readily degraded in the matrix space. Collectively, this study showed that the precursor form is less stable in the matrix space than is the mature form and provides an explanation for why the leader peptide is removed from the precursors.
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Affiliation(s)
- Abhijit Mukhopadhyay
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907-2063, USA.
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Gebhard LG, Risso VA, Santos J, Ferreyra RG, Noguera ME, Ermácora MR. Mapping the Distribution of Conformational Information Throughout a Protein Sequence. J Mol Biol 2006; 358:280-8. [PMID: 16510154 DOI: 10.1016/j.jmb.2006.01.095] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 01/26/2006] [Accepted: 01/27/2006] [Indexed: 12/01/2022]
Abstract
The three-dimensional structure of protein is encoded in the sequence, but many amino acid residues carry no essential conformational information, and the identity of those that are structure-determining is elusive. By circular permutation and terminal deletion, we produced and purified 25 Bacillus licheniformis beta-lactamase (ESBL) variants that lack 5-21 contiguous residues each, and collectively have 82% of the sequence and 92% of the non-local atom-atom contacts eliminated. Circular dichroism and size-exclusion chromatography showed that most of the variants form conformationally heterogeneous mixtures, but by measuring catalytic constants, we found that all populate, to a greater or lesser extent, conformations with the essential features of the native fold. This suggests that no segment of the ESBL sequence is essential to the structure as a whole, which is congruent with the notion that local information and modular organization can impart most of the tertiary fold specificity and cooperativity.
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Affiliation(s)
- Leopoldo G Gebhard
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 180, (1876) Bernal, Buenos Aires, Argentina
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11
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Hecky J, Müller KM. Structural perturbation and compensation by directed evolution at physiological temperature leads to thermostabilization of beta-lactamase. Biochemistry 2005; 44:12640-54. [PMID: 16171379 DOI: 10.1021/bi0501885] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The choice of protein for use in technical and medical applications is limited by stability issues, making understanding and engineering of stability key. Here, enzyme destabilization by truncation was combined with directed evolution to create stable variants of TEM-1 beta-lactamase. This enzyme was chosen because of its implication in prodrug activation therapy, pathogen resistance to lactam antibiotics, and reporter enzyme bioassays. Removal of five N-terminal residues generated a mutant which did not confer antibiotic resistance at 37 degrees C. Accordingly, the half-life time in vitro was only 7 s at 40 degrees C. However, three cycles comprising random mutagenesis, DNA shuffling, and metabolic selection at 37 degrees C yielded mutants providing resistance levels significantly higher than that of the wild type. These mutants demonstrated increased thermoactivity and thermostability in time-resolved kinetics at various temperatures. Chemical denaturation revealed improved thermodynamic stabilities of a three-state unfolding pathway exceeding wild-type construct stability. Elongation of one optimized deletion mutant to full length increased its stability even further. Compared to that of the wild type, the temperature optimum was shifted from 35 to 50 degrees C, and the beginning of heat inactivation increased by 20 degrees C while full activity at low temperatures was maintained. We attribute these effects mainly to two independently acting boundary interface residue exchanges (M182T and A224V). Structural perturbation by terminal truncation, evolutionary compensation at physiological temperatures, and elongation is an efficient way to analyze and improve thermostability without the need for high-temperature selection, structural information, or homologous proteins.
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Affiliation(s)
- Jochen Hecky
- Institut für Biologie III, Albert-Ludwigs-Universität, Schänzlestrasse 1, D-79104 Freiburg, Germany
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12
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Louzada PR, Sebollela A, Scaramello ME, Ferreira ST. Predissociated dimers and molten globule monomers in the equilibrium unfolding of yeast glutathione reductase. Biophys J 2004; 85:3255-61. [PMID: 14581225 PMCID: PMC1303601 DOI: 10.1016/s0006-3495(03)74743-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The equilibrium unfolding of dimeric yeast glutathione reductase (GR) by guanidine hydrochloride (GdnHCl) was investigated. Unfolding was monitored by a variety of techniques, including intrinsic fluorescence emission, anisotropy and iodide quenching measurements, far-ultraviolet circular dichroism and thiol reactivity measurements. At 1 M GdnHCl, one thiol group of GR became accessible to modification with 5,5'-dithiobis-(2-nitrobenzoic) acid (DTNB), whereas no changes could be detected in the spectroscopic properties (fluorescence, circular dichroism) of the protein. Between 2 and 3 M GdnHCl, two partially folded intermediate states possessing flexible tertiary structures (revealed by fluorescence data) but compact secondary structures (as indicated by circular dichroism measurements) were identified. The quaternary structure of GR in the presence of GdnHCl was also investigated by size-exclusion liquid chromatography. These results indicated the presence of an expanded predissociated dimer at 2.5 M GdnHCl and partially folded monomers at 3 M GdnHCl. Taken together, these results suggest the existence of two molten-globule-like intermediate species (one dimeric and one monomeric) in the unfolding of GR. The results are discussed in terms of the mechanism of GR folding and dimerization.
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Affiliation(s)
- Paulo Roberto Louzada
- Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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13
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Williams RAM, Kelly SM, Mottram JC, Coombs GH. 3-Mercaptopyruvate sulfurtransferase of Leishmania contains an unusual C-terminal extension and is involved in thioredoxin and antioxidant metabolism. J Biol Chem 2003; 278:1480-6. [PMID: 12419809 DOI: 10.1074/jbc.m209395200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytosolic 3-mercaptopyruvate sulfurtransferases (EC ) of Leishmania major and Leishmania mexicana have been cloned, expressed as active enzymes in Escherichia coli, and characterized. The leishmanial single-copy genes predict a sulfurtransferase that is structurally peculiar in possessing a C-terminal domain of some 70 amino acids. Homologous genes of Trypanosoma cruzi and Trypanosoma brucei encode enzymes with a similar C-terminal domain, suggesting that this feature, not known in any other sulfurtransferase, is a characteristic of trypanosomatid parasites. Short truncations of the C-terminal domain resulted in misfolded inactive proteins, demonstrating that the domain plays some key role in facilitating correct folding of the enzymes. The leishmanial recombinant enzymes exhibited high activity toward 3-mercaptopyruvate and catalyzed the transfer of sulfane sulfur to cyanide to form thiocyanate. They also used thiosulfate as a substrate and reduced thioredoxin as the accepting nucleophile, the latter being oxidized. The enzymes were expressed in all life cycle stages, and the expression level was increased under peroxide or hypo-sulfur stress. The results are consistent with the enzymes having an involvement in the synthesis of sulfur amino acids per se or iron-sulfur centers of proteins and the parasite's management of oxidative stress.
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Affiliation(s)
- Roderick A M Williams
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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14
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Yoder MD, Thomas LM, Tremblay JM, Oliver RL, Yarbrough LR, Helmkamp GM. Structure of a multifunctional protein. Mammalian phosphatidylinositol transfer protein complexed with phosphatidylcholine. J Biol Chem 2001; 276:9246-52. [PMID: 11104777 DOI: 10.1074/jbc.m010131200] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic phosphatidylinositol transfer protein is a ubiquitous multifunctional protein that transports phospholipids between membrane surfaces and participates in cellular phospholipid metabolism during signal transduction and vesicular trafficking. The three-dimensional structure of the alpha-isoform of rat phosphatidylinositol transfer protein complexed with one molecule of phosphatidylcholine, one of its physiological ligands, has been determined to 2.2 A resolution by x-ray diffraction techniques. A single beta-sheet and several long alpha-helices define an enclosed internal cavity in which a single molecule of the phospholipid is accommodated with its polar head group in the center of the protein and fatty acyl chains projected toward the surface. Other structural features suggest mechanisms by which cytosolic phosphatidylinositol transfer protein interacts with membranes for lipid exchange and associates with a variety of lipid and protein kinases.
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Affiliation(s)
- M D Yoder
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110-2499 , USA.
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15
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Kramer G, Ramachandiran V, Horowitz P, Hardesty B. An Additional Serine Residue at the C Terminus of Rhodanese Destabilizes the Enzyme. Arch Biochem Biophys 2001; 385:332-7. [PMID: 11368014 DOI: 10.1006/abbi.2000.2166] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The rhodanese coding sequence was extended at its 3' end by three base pairs to generate mutants coding for a serine or arginine residue at the carboxyl terminus of the protein. Wild-type and mutant coding sequences were expressed in a cell-free Escherichia coli system by coupled transcription/translation. Predominantly full-length protein was formed in all cases. The amount of protein synthesized was quantified by incorporation of radioactive leucine into polypeptides. Enzymatic activity of in vitro synthesized rhodanese was determined at different temperatures. Specific enzymatic activity was calculated and is assumed to reflect the portion of the protein that is in its native three-dimensional conformation. It was observed that rhodanese extended by one serine at the C terminus lost enzymatic activity when incubated above 30 degrees C, in contrast to wild-type protein or variant rhodanese extended by an arginine residue. Similarly, variant rhodanese with an additional serine residue was more susceptible to urea denaturation than the other two rhodanese species. These results are surprising in light of the crystal structure of the protein.
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Affiliation(s)
- G Kramer
- Department of Chemistry and Biochemistry, University of Texas at Austin, 78712, USA.
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16
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Nakamura T, Yamaguchi Y, Sano H. Plant mercaptopyruvate sulfurtransferases: molecular cloning, subcellular localization and enzymatic activities. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:5621-30. [PMID: 10951223 DOI: 10.1046/j.1432-1327.2000.01633.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mercaptopyruvate sulfurtransferase (MST, EC 2.8.1.2) and thiosulfate sulfurtransferase (TST, rhodanese, EC 2.8.1.1) are evolutionarily related enzymes that catalyze the transfer of sulfur ions from mercaptopyruvate and thiosulfate, respectively, to cyanide ions. We have isolated and characterized two cDNAs, AtMST1 and AtMST2, that are Arabidopsis homologs of TST and MST from other organisms. Deduced amino-acid sequences showed similarity to each other, although MST1 has a N-terminal extension of 57 amino acids containing a targeting sequence. MST1 and MST2 are located in mitochondria and cytoplasm, respectively, as shown by immunoblot analysis of subcellular fractions and by green fluorescent protein (GFP) analysis. However, some regions of MST1 fused to GFP were found to target not only mitochondria, but also chloroplasts, suggesting that the regions on the targeting sequence recognized by protein import systems of mitochondria and chloroplasts are not identical. Recombinant proteins, expressed in Escherichia coli, exhibited MST/TST activity ratios determined from kcat/Km values of 11 and 26 for MST1 and MST2, respectively. This indicates that the proteins encoded by both AtMST1 and AtMST2 are MST rather than TST type. One of the hypotheses proposed so far for the physiological function of MST and TST concerns iron-sulfur cluster assembly. In order to address this possibility, a T-DNA insertion Arabidopsis mutant, in which the AtMST1 was disrupted, was isolated by PCR screening of T-DNA mutant libraries. However, the mutation had no effect on levels of iron-sulfur enzyme activities, suggesting that MST1 is not directly involved in iron-sulfur cluster assembly.
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Affiliation(s)
- T Nakamura
- Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Ikoma, Nara, Japan
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Papenbrock J, Schmidt A. Characterization of a sulfurtransferase from Arabidopsis thaliana. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:145-54. [PMID: 10601861 DOI: 10.1046/j.1432-1327.2000.00980.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A database search for similarities between sequenced parts of the Arabidopsis thaliana genome with known sulfurtransferase sequences from Escherichia coli and mammals was undertaken to obtain information about plant sulfurtransferase-like proteins. One gene and several homologous EST clones were identified. One of the EST clones was used for screening an Arabidopsis cDNA library. The isolated full-length clone consists of 1134 bp and encodes a 42.6 kDa protein that includes a putative transit peptide sequence of about 7.1 kDa. Sequence comparisons with known sulfurtransferases from different organisms confirmed high homology between them and the existence of several highly conserved regions. Results of a Southern blot performed with genomic Arabidopsis DNA showed the occurrence of at least two sulfurtransferase-like isozymes in Arabidopsis. Recombinant proteins with and without the putative transit peptide were expressed in E. coli with an N-terminal His6-tag, purified by affinity chromatography and tested for enzyme activity using different sulfur donors and acceptors. Both recombinant proteins catalyzed the formation of SCN- from thiosulfate and cyanide as a rhodanese per definition; however, both recombinant proteins preferred 3-mercaptopyruvate to thiosulfate. A monospecific antibody produced by using the mature recombinant protein as an antigen recognized a single protein band in total extracts of Arabidopsis plants equating to the full-length protein size. A single band equating to the size of the mature protein was detected from purified Arabidopsis mitochondria, but there was no antigenic reaction with any protein from chloroplasts. The function of the protein is still speculative. Now tools are available to elucidate the roles and substrates of this sulfurtransferase in higher plants.
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Affiliation(s)
- J Papenbrock
- Institute for Botany, University of Hannover, Germany.
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