1
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van Wonderen JH, Crack JC, Edwards MJ, Clarke TA, Saalbach G, Martins C, Butt JN. Liquid-chromatography mass spectrometry describes post-translational modification of Shewanella outer membrane proteins. Biochim Biophys Acta Biomembr 2024; 1866:184221. [PMID: 37673350 DOI: 10.1016/j.bbamem.2023.184221] [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: 02/08/2023] [Revised: 08/09/2023] [Accepted: 08/30/2023] [Indexed: 09/08/2023]
Abstract
Electrogenic bacteria deliver excess respiratory electrons to externally located metal oxide particles and electrodes. The biochemical basis for this process is arguably best understood for species of Shewanella where the integral membrane complex termed MtrCAB is key to electron transfer across the bacterial outer membranes. A crystal structure was recently resolved for MtrCAB from S. baltica OS185. However, X-ray diffraction did not resolve the N-terminal residues so that the lipidation status of proteins in the mature complex was poorly described. Here we report liquid chromatography mass spectrometry revealing the intact mass values for all three proteins in the MtrCAB complexes purified from Shewanella oneidensis MR-1 and S. baltica OS185. The masses of MtrA and MtrB are consistent with both proteins being processed by Signal Peptidase I and covalent attachment of ten c-type hemes to MtrA. The mass of MtrC is most reasonably interpreted as arising from protein processed by Signal Peptidase II to produce a diacylated lipoprotein containing ten c-type hemes. Our two-step protocol for liquid-chromatography mass spectrometry used a reverse phase column to achieve on-column detergent removal prior to gradient protein resolution and elution. We envisage the method will be capable of simultaneously resolving the intact mass values for multiple proteins in other membrane protein complexes.
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Affiliation(s)
- Jessica H van Wonderen
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
| | - Jason C Crack
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Marcus J Edwards
- School of Biological Sciences, University of East Anglia, , Norwich Research Park, Norwich NR4 7TJ, UK; School of Life Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Thomas A Clarke
- School of Biological Sciences, University of East Anglia, , Norwich Research Park, Norwich NR4 7TJ, UK
| | - Gerhard Saalbach
- Proteomics Facility, The John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Carlo Martins
- Proteomics Facility, The John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Julea N Butt
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK; School of Biological Sciences, University of East Anglia, , Norwich Research Park, Norwich NR4 7TJ, UK.
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2
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Stanfill SB, Hecht SS, Joerger AC, González PJ, Maia LB, Rivas MG, Moura JJG, Gupta AK, Le Brun NE, Crack JC, Hainaut P, Sparacino-Watkins C, Tyx RE, Pillai SD, Zaatari GS, Henley SJ, Blount BC, Watson CH, Kaina B, Mehrotra R. From cultivation to cancer: formation of N-nitrosamines and other carcinogens in smokeless tobacco and their mutagenic implications. Crit Rev Toxicol 2023; 53:658-701. [PMID: 38050998 DOI: 10.1080/10408444.2023.2264327] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 04/21/2023] [Accepted: 09/20/2023] [Indexed: 12/07/2023]
Abstract
Tobacco use is a major cause of preventable morbidity and mortality globally. Tobacco products, including smokeless tobacco (ST), generally contain tobacco-specific N-nitrosamines (TSNAs), such as N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-butanone (NNK), which are potent carcinogens that cause mutations in critical genes in human DNA. This review covers the series of biochemical and chemical transformations, related to TSNAs, leading from tobacco cultivation to cancer initiation. A key aim of this review is to provide a greater understanding of TSNAs: their precursors, the microbial and chemical mechanisms that contribute to their formation in ST, their mutagenicity leading to cancer due to ST use, and potential means of lowering TSNA levels in tobacco products. TSNAs are not present in harvested tobacco but can form due to nitrosating agents reacting with tobacco alkaloids present in tobacco during certain types of curing. TSNAs can also form during or following ST production when certain microorganisms perform nitrate metabolism, with dissimilatory nitrate reductases converting nitrate to nitrite that is then released into tobacco and reacts chemically with tobacco alkaloids. When ST usage occurs, TSNAs are absorbed and metabolized to reactive compounds that form DNA adducts leading to mutations in critical target genes, including the RAS oncogenes and the p53 tumor suppressor gene. DNA repair mechanisms remove most adducts induced by carcinogens, thus preventing many but not all mutations. Lastly, because TSNAs and other agents cause cancer, previously documented strategies for lowering their levels in ST products are discussed, including using tobacco with lower nornicotine levels, pasteurization and other means of eliminating microorganisms, omitting fermentation and fire-curing, refrigerating ST products, and including nitrite scavenging chemicals as ST ingredients.
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Affiliation(s)
- Stephen B Stanfill
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Stephen S Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Andreas C Joerger
- Structural Genomics Consortium (SGC), Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Pablo J González
- Department of Physics, Universidad Nacional Litoral, and CONICET, Santa Fe, Argentina
| | - Luisa B Maia
- Department of Chemistry, LAQV, REQUIMTE, NOVA School of Science and Technology (FCT NOVA), Caparica, Portugal
| | - Maria G Rivas
- Department of Physics, Universidad Nacional Litoral, and CONICET, Santa Fe, Argentina
| | - José J G Moura
- Department of Chemistry, LAQV, REQUIMTE, NOVA School of Science and Technology (FCT NOVA), Caparica, Portugal
| | | | - Nick E Le Brun
- School of Chemistry, Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich, UK
| | - Jason C Crack
- School of Chemistry, Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich, UK
| | - Pierre Hainaut
- Institute for Advanced Biosciences, Grenoble Alpes University, Grenoble, France
| | - Courtney Sparacino-Watkins
- University of Pittsburgh, School of Medicine, Division of Pulmonary Allergy and Critical Care Medicine, Vascular Medicine Institute, PA, USA
| | - Robert E Tyx
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Suresh D Pillai
- Department of Food Science & Technology, National Center for Electron Beam Research, Texas A&M University, College Station, TX, USA
| | - Ghazi S Zaatari
- Department of Pathology and Laboratory Medicine, American University of Beirut, Beirut, Lebanon
| | - S Jane Henley
- Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Benjamin C Blount
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Clifford H Watson
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Bernd Kaina
- Institute of Toxicology, University Medical Center, Mainz, Germany
| | - Ravi Mehrotra
- Centre for Health, Innovation and Policy Foundation, Noida, India
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3
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Gray E, Stewart MYY, Hanwell L, Crack JC, Devine R, Stevenson CEM, Volbeda A, Johnston AWB, Fontecilla-Camps JC, Hutchings MI, Todd JD, Le Brun NE. Stabilisation of the RirA [4Fe-4S] cluster results in loss of iron-sensing function. Chem Sci 2023; 14:9744-9758. [PMID: 37736639 PMCID: PMC10510648 DOI: 10.1039/d3sc03020b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/21/2023] [Indexed: 09/23/2023] Open
Abstract
RirA is a global iron regulator in diverse Alphaproteobacteria that belongs to the Rrf2 superfamily of transcriptional regulators, which can contain an iron-sulfur (Fe-S) cluster. Under iron-replete conditions, RirA contains a [4Fe-4S] cluster, enabling high-affinity binding to RirA-regulated operator sequences, thereby causing the repression of cellular iron uptake. Under iron deficiency, one of the cluster irons dissociates, generating an unstable [3Fe-4S] form that subsequently degrades to a [2Fe-2S] form and then to apo RirA, resulting in loss of high-affinity DNA-binding. The cluster is coordinated by three conserved cysteine residues and an unknown fourth ligand. Considering the lability of one of the irons and the resulting cluster fragility, we hypothesized that the fourth ligand may not be an amino acid residue. To investigate this, we considered that the introduction of an amino acid residue that could coordinate the cluster might stabilize it. A structural model of RirA, based on the Rrf2 family nitrosative stress response regulator NsrR, highlighted residue 8, an Asn in the RirA sequence, as being appropriately positioned to coordinate the cluster. Substitution of Asn8 with Asp, the equivalent, cluster-coordinating residue of NsrR, or with Cys, resulted in proteins that contained a [4Fe-4S] cluster, with N8D RirA exhibiting spectroscopic properties very similar to NsrR. The variant proteins retained the ability to bind RirA-regulated DNA, and could still act as repressors of RirA-regulated genes in vivo. However, they were significantly more stable than wild-type RirA when exposed to O2 and/or low iron. Importantly, they exhibited reduced capacity to respond to cellular iron levels, even abolished in the case of the N8D version, and thus were no longer iron sensing. This work demonstrates the importance of cluster fragility for the iron-sensing function of RirA, and more broadly, how a single residue substitution can alter cluster coordination and functional properties in the Rrf2 superfamily of regulators.
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Affiliation(s)
- Elizabeth Gray
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK +44 (0)1603 592003 +44 (0)1603 592699
| | - Melissa Y Y Stewart
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK +44 (0)1603 592003 +44 (0)1603 592699
| | - Libby Hanwell
- School of Biological Sciences, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK +44 (0)1603 592003 +44 (0)1603 592699
| | - Rebecca Devine
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Clare E M Stevenson
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Anne Volbeda
- Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble-Alpes 71, Avenue des Martyrs, CS 10090 38044 Grenoble Cedex 9 France
| | - Andrew W B Johnston
- School of Biological Sciences, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Juan C Fontecilla-Camps
- Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble-Alpes 71, Avenue des Martyrs, CS 10090 38044 Grenoble Cedex 9 France
| | - Matthew I Hutchings
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Jonathan D Todd
- School of Biological Sciences, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK +44 (0)1603 592003 +44 (0)1603 592699
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4
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Bridge T, Wegmann U, Crack JC, Orman K, Shaikh SA, Farndon W, Martins C, Saalbach G, Sachdeva A. Site-specific encoding of photoactivity and photoreactivity into antibody fragments. Nat Chem Biol 2023; 19:740-749. [PMID: 36797401 DOI: 10.1038/s41589-022-01251-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 12/21/2022] [Indexed: 02/18/2023]
Abstract
Design of biomolecules that perform two or more distinct functions in response to light remains challenging. Here, we have introduced concurrent photoactivity and photoreactivity into an epidermal growth factor receptor (EGFR)-targeting antibody fragment, 7D12. This was achieved by site-specific incorporation of photocaged tyrosine (pcY) for photoactivity and p-benzoyl-ʟ-phenylalanine (Bpa) for photoreactivity into 7D12. We identified a position for installing Bpa in 7D12 that has minimal effect on 7D12-EGFR binding affinity in the absence of light. Upon exposure to 365-nm light, this Bpa-containing 7D12 mutant forms a covalent bond with EGFR in an antigen-specific manner. We then developed a method for site-specific incorporation of pcY and Bpa at two distinct sites in 7D12. Finally, we demonstrated that in the absence of light, this pcY- and Bpa-containing mutant of 7D12 does not bind to EGFR, but irradiation with 365-nm light activates (1) specific binding and (2) covalent bond formation with EGFR.
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Affiliation(s)
- Thomas Bridge
- School of Chemistry, University of East Anglia, Norwich, UK
| | - Udo Wegmann
- School of Chemistry, University of East Anglia, Norwich, UK
| | - Jason C Crack
- School of Chemistry, University of East Anglia, Norwich, UK
| | - Kate Orman
- School of Chemistry, University of East Anglia, Norwich, UK
| | - Saher A Shaikh
- School of Chemistry, University of East Anglia, Norwich, UK
| | | | - Carlo Martins
- Proteomics Facility, The John Innes Centre, Norwich, UK
| | | | - Amit Sachdeva
- School of Chemistry, University of East Anglia, Norwich, UK.
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5
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Bennett SP, Crack JC, Puglisi R, Pastore A, Le Brun NE. Native mass spectrometric studies of IscSU reveal a concerted, sulfur-initiated mechanism of iron-sulfur cluster assembly. Chem Sci 2022; 14:78-95. [PMID: 36605734 PMCID: PMC9769115 DOI: 10.1039/d2sc04169c] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/13/2022] [Indexed: 11/16/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters are cofactors essential for life. Though the proteins that function in the assembly of Fe-S clusters are well known, details of the molecular mechanism are less well established. The Isc (iron-sulfur cluster) biogenesis apparatus is widespread in bacteria and is the closest homologue to the human system. Mutations in certain components of the human system lead to disease, and so further studies of this system could be important for developing strategies for medical treatments. We have studied two core components of the Isc biogenesis system: IscS, a cysteine desulfurase; and IscU, a scaffold protein on which clusters are built before subsequent transfer onto recipient apo-proteins. Fe2+-binding, sulfur transfer, and formation of a [2Fe-2S] was followed by a range of techniques, including time-resolved mass spectrometry, and intermediate and product species were unambiguously identified through isotopic substitution experiments using 57Fe and 34S. Under cluster synthesis conditions, sulfur adducts and the [2Fe-2S] cluster product readily accumulated on IscU, but iron adducts (other than the cluster itself) were not observed at physiologically relevant Fe2+ concentrations. Our data indicate that either Fe2+ or sulfur transfer can occur first, but that the transfer of sulfane sulfur (S0) to IscU must occur first if Zn2+ is bound to IscU, suggesting that it is the key step that initiates cluster assembly. Following this, [2Fe-2S] cluster formation is a largely concerted reaction once Fe2+ is introduced.
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Affiliation(s)
- Sophie P. Bennett
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Jason C. Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Rita Puglisi
- The Wohl Institute, King's College London, Denmark Hill CampusLondon SE5 8AFUK
| | - Annalisa Pastore
- The Wohl Institute, King's College London, Denmark Hill CampusLondon SE5 8AFUK
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research ParkNorwichNR4 7TJUK
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6
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Jenner LP, Crack JC, Kurth JM, Soldánová Z, Brandt L, Sokol KP, Reisner E, Bradley JM, Dahl C, Cheesman MR, Butt JN. Reaction of Thiosulfate Dehydrogenase with a Substrate Mimic Induces Dissociation of the Cysteine Heme Ligand Giving Insights into the Mechanism of Oxidative Catalysis. J Am Chem Soc 2022; 144:18296-18304. [PMID: 36173876 PMCID: PMC9562282 DOI: 10.1021/jacs.2c06062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Thiosulfate dehydrogenases are bacterial cytochromes
that contribute
to the oxidation of inorganic sulfur. The active sites of these enzymes
contain low-spin c-type heme with Cys–/His axial ligation. However, the reduction potentials of these hemes
are several hundred mV more negative than that of the thiosulfate/tetrathionate
couple (Em, +198 mV), making it difficult
to rationalize the thiosulfate oxidizing capability. Here, we describe
the reaction of Campylobacter jejuni thiosulfate dehydrogenase (TsdA) with sulfite, an analogue of thiosulfate.
The reaction leads to stoichiometric conversion of the active site
Cys to cysteinyl sulfonate (Cα-CH2-S-SO3–) such that the protein exists in a form
closely resembling a proposed intermediate in the pathway for thiosulfate
oxidation that carries a cysteinyl thiosulfate (Cα-CH2-S-SSO3–). The active
site heme in the stable sulfonated protein displays an Em approximately 200 mV more positive than the Cys–/His-ligated state. This can explain the thiosulfate
oxidizing activity of the enzyme and allows us to propose a catalytic
mechanism for thiosulfate oxidation. Substrate-driven release of the
Cys heme ligand allows that side chain to provide the site of substrate
binding and redox transformation; the neighboring heme then simply
provides a site for electron relay to an appropriate partner. This
chemistry is distinct from that displayed by the Cys-ligated hemes
found in gas-sensing hemoproteins and in enzymes such as the cytochromes
P450. Thus, a further class of thiolate-ligated hemes is proposed,
as exemplified by the TsdA centers that have evolved to catalyze the
controlled redox transformations of inorganic oxo anions of sulfur.
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Affiliation(s)
- Leon P Jenner
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Julia M Kurth
- Institut für Mikrobiologie & Biotechnologie, Friedrich Wilhelms Universität Bonn, D-53115Bonn, Germany
| | - Zuzana Soldánová
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Linda Brandt
- Institut für Mikrobiologie & Biotechnologie, Friedrich Wilhelms Universität Bonn, D-53115Bonn, Germany
| | - Katarzyna P Sokol
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Christiane Dahl
- Institut für Mikrobiologie & Biotechnologie, Friedrich Wilhelms Universität Bonn, D-53115Bonn, Germany
| | - Myles R Cheesman
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Julea N Butt
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
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7
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Rohac R, Crack JC, de Rosny E, Gigarel O, Le Brun NE, Fontecilla-Camps JC, Volbeda A. Structural determinants of DNA recognition by the NO sensor NsrR and related Rrf2-type [FeS]-transcription factors. Commun Biol 2022; 5:769. [PMID: 35908109 PMCID: PMC9338935 DOI: 10.1038/s42003-022-03745-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/21/2022] [Indexed: 11/20/2022] Open
Abstract
Several transcription factors of the Rrf2 family use an iron-sulfur cluster to regulate DNA binding through effectors such as nitric oxide (NO), cellular redox status and iron levels. [4Fe-4S]-NsrR from Streptomyces coelicolor (ScNsrR) modulates expression of three different genes via reaction and complex formation with variable amounts of NO, which results in detoxification of this gas. Here, we report the crystal structure of ScNsrR complexed with an hmpA1 gene operator fragment and compare it with those previously reported for [2Fe-2S]-RsrR/rsrR and apo-IscR/hyA complexes. Important structural differences reside in the variation of the DNA minor and major groove widths. In addition, different DNA curvatures and different interactions with the protein sensors are observed. We also report studies of NsrR binding to four hmpA1 variants, which indicate that flexibility in the central region is not a key binding determinant. Our study explores the promotor binding specificities of three closely related transcriptional regulators. The crystal structure of the iron-sulfur protein NsrR from Streptomyces coelicolor bound to a gene operator fragment is reported and compared with other structures, giving insight into the structural determinants of DNA recognition by the NO sensor.
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Affiliation(s)
- Roman Rohac
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Eve de Rosny
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Océane Gigarel
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Juan C Fontecilla-Camps
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Anne Volbeda
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France.
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8
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Crack JC, Balasiny BK, Bennett SP, Rolfe MD, Froes A, MacMillan F, Green J, Cole JA, Le Brun NE. The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress. J Am Chem Soc 2022; 144:7129-7145. [PMID: 35416044 PMCID: PMC9052748 DOI: 10.1021/jacs.1c12407] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
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Previously characterized
nitrite reductases fall into three classes:
siroheme-containing enzymes (NirBD), cytochrome c hemoproteins (NrfA and NirS), and copper-containing enzymes (NirK).
We show here that the di-iron protein YtfE represents a physiologically
relevant new class of nitrite reductases. Several functions have been
previously proposed for YtfE, including donating iron for the repair
of iron–sulfur clusters that have been damaged by nitrosative
stress, releasing nitric oxide (NO) from nitrosylated iron, and reducing
NO to nitrous oxide (N2O). Here, in vivo reporter assays confirmed that Escherichia coli YtfE increased cytoplasmic NO production from nitrite. Spectroscopic
and mass spectrometric investigations revealed that the di-iron site
of YtfE exists in a mixture of forms, including nitrosylated and nitrite-bound,
when isolated from nitrite-supplemented, but not nitrate-supplemented,
cultures. Addition of nitrite to di-ferrous YtfE resulted in nitrosylated
YtfE and the release of NO. Kinetics of nitrite reduction were dependent
on the nature of the reductant; the lowest Km, measured for the di-ferrous form, was ∼90 μM,
well within the intracellular nitrite concentration range. The vicinal
di-cysteine motif, located in the N-terminal domain of YtfE, was shown
to function in the delivery of electrons to the di-iron center. Notably,
YtfE exhibited very low NO reductase activity and was only able to
act as an iron donor for reconstitution of apo-ferredoxin under conditions
that damaged its di-iron center. Thus, YtfE is a high-affinity, low-capacity
nitrite reductase that we propose functions to relieve nitrosative
stress by acting in combination with the co-regulated NO-consuming
enzymes Hmp and Hcp.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Basema K Balasiny
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Sophie P Bennett
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Matthew D Rolfe
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Afonso Froes
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Fraser MacMillan
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Jeffrey Green
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Jeffrey A Cole
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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9
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Crack JC, Gray E, Le Brun NE. Sensing mechanisms of iron-sulfur cluster regulatory proteins elucidated using native mass spectrometry. Dalton Trans 2021; 50:7887-7897. [PMID: 34037038 PMCID: PMC8204329 DOI: 10.1039/d1dt00993a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/17/2021] [Indexed: 12/02/2022]
Abstract
The ability to sense and respond to various key environmental cues is important for the survival and adaptability of many bacteria, including pathogens. The particular sensitivity of iron-sulfur (Fe-S) clusters is exploited in nature, such that multiple sensor-regulator proteins, which coordinate the detection of analytes with a (in many cases) global transcriptional response, are Fe-S cluster proteins. The fragility and sensitivity of these Fe-S clusters make studying such proteins difficult, and gaining insight of what they sense, and how they sense it and transduce the signal to affect transcription, is a major challenge. While mass spectrometry is very widely used in biological research, it is normally employed under denaturing conditions where non-covalently attached cofactors are lost. However, mass spectrometry under conditions where the protein retains its native structure and, thus, cofactors, is now itself a flourishing field, and the application of such 'native' mass spectrometry to study metalloproteins is now relatively widespread. Here we describe recent advances in using native MS to study Fe-S cluster proteins. Through its ability to accurately measure mass changes that reflect chemistry occurring at the cluster, this approach has yielded a remarkable richness of information that is not accessible by other, more traditional techniques.
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Affiliation(s)
- Jason C. Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research ParkNorwichNR4 7TJUK
| | - Elizabeth Gray
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research ParkNorwichNR4 7TJUK
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research ParkNorwichNR4 7TJUK
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10
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Abstract
Iron-sulfur clusters constitute a large and widely distributed group of protein cofactors that play key roles in a wide range of metabolic processes. The inherent reactivity of iron-sulfur clusters toward small molecules, for example, O2, NO, or free Fe, makes them ideal for sensing changes in the cellular environment. Nondenaturing, or native, MS is unique in its ability to preserve the noncovalent interactions of many (if not all) species, including stable intermediates, while providing accurate mass measurements in both thermodynamic and kinetic experimental regimes. Here, we provide practical guidance for the study of iron-sulfur proteins by native MS, illustrated by examples where it has been used to unambiguously determine the type of cluster coordinated to the protein framework. We also describe the use of time-resolved native MS to follow the kinetics of cluster conversion, allowing the elucidation of the precise series of molecular events for all species involved. Finally, we provide advice on a unique approach to a typical thermodynamic titration, uncovering early, quasi-stable, intermediates in the reaction of a cluster with nitric oxide, resulting in cluster nitrosylation.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, UK.
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11
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Stewart MYY, Bush MJ, Crack JC, Buttner MJ, Le Brun NE. Interaction of the Streptomyces Wbl protein WhiD with the principal sigma factor σ HrdB depends on the WhiD [4Fe-4S] cluster. J Biol Chem 2020; 295:9752-9765. [PMID: 32303639 PMCID: PMC7363131 DOI: 10.1074/jbc.ra120.012708] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/15/2020] [Indexed: 12/29/2022] Open
Abstract
The bacterial protein WhiD belongs to the Wbl family of iron-sulfur [Fe-S] proteins present only in the actinomycetes. In Streptomyces coelicolor, it is required for the late stages of sporulation, but precisely how it functions is unknown. Here, we report results from in vitro and in vivo experiments with WhiD from Streptomyces venezuelae (SvWhiD), which differs from S. coelicolor WhiD (ScWhiD) only at the C terminus. We observed that, like ScWhiD and other Wbl proteins, SvWhiD binds a [4Fe-4S] cluster that is moderately sensitive to O2 and highly sensitive to nitric oxide (NO). However, although all previous studies have reported that Wbl proteins are monomers, we found that SvWhiD exists in a monomer-dimer equilibrium associated with its unusual C-terminal extension. Several Wbl proteins of Mycobacterium tuberculosis are known to interact with its principal sigma factor SigA. Using bacterial two-hybrid, gel filtration, and MS analyses, we demonstrate that SvWhiD interacts with domain 4 of the principal sigma factor of Streptomyces, σHrdB (σHrdB 4). Using MS, we determined the dissociation constant (Kd ) for the SvWhiD-σHrdB 4 complex as ∼0.7 μm, consistent with a relatively tight binding interaction. We found that complex formation was cluster dependent and that a reaction with NO, which was complete at 8-10 NO molecules per cluster, resulted in dissociation into the separate proteins. The SvWhiD [4Fe-4S] cluster was significantly less sensitive to reaction with O2 and NO when SvWhiD was bound to σHrdB 4, consistent with protection of the cluster in the complex.
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Affiliation(s)
- Melissa Y Y Stewart
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
| | - Matthew J Bush
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
| | - Mark J Buttner
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
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12
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Crack JC, Amara P, Volbeda A, Mouesca JM, Rohac R, Pellicer Martinez MT, Huang CY, Gigarel O, Rinaldi C, Le Brun NE, Fontecilla-Camps JC. Electron and Proton Transfers Modulate DNA Binding by the Transcription Regulator RsrR. J Am Chem Soc 2020; 142:5104-5116. [PMID: 32078310 DOI: 10.1021/jacs.9b12250] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The [Fe2S2]-RsrR gene transcription regulator senses the redox status in bacteria by modulating DNA binding, while its cluster cycles between +1 and +2 states-only the latter binds DNA. We have previously shown that RsrR can undergo remarkable conformational changes involving a 100° rotation of tryptophan 9 between exposed (Out) and buried (In) states. Here, we have used the chemical modification of Trp9, site-directed mutagenesis, and crystallographic and computational chemical studies to show that (i) the Out and In states correspond to oxidized and reduced RsrR, respectively, (ii) His33 is protonated in the In state due to a change in its pKa caused by cluster reduction, and (iii) Trp9 rotation is conditioned by the response of its dipole moment to environmental electrostatic changes. Our findings illustrate a novel function of protonation resulting from electron transfer.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Patricia Amara
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38044 Grenoble, France
| | - Anne Volbeda
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38044 Grenoble, France
| | - Jean-Marie Mouesca
- Université Grenoble Alpes, CEA, CNRS, IRIG-DIESE-SyMMES-CAMPE, 38000 Grenoble, France
| | - Roman Rohac
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38044 Grenoble, France
| | - Ma Teresa Pellicer Martinez
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Chia-Ying Huang
- Macromolecular Crystallography, Swiss Light Source, Paul Scherrer Institute, 5232 Villigen, PSI, Switzerland
| | - Océane Gigarel
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38044 Grenoble, France
| | - Clara Rinaldi
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38044 Grenoble, France
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Juan C Fontecilla-Camps
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38044 Grenoble, France
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13
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Pellicer Martinez MT, Crack JC, Stewart MYY, Bradley JM, Svistunenko DA, Johnston AWB, Cheesman MR, Todd JD, Le Brun NE. Mechanisms of iron- and O 2-sensing by the [4Fe-4S] cluster of the global iron regulator RirA. eLife 2019; 8:e47804. [PMID: 31526471 PMCID: PMC6748827 DOI: 10.7554/elife.47804] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 07/29/2019] [Indexed: 01/05/2023] Open
Abstract
RirA is a global regulator of iron homeostasis in Rhizobium and related α-proteobacteria. In its [4Fe-4S] cluster-bound form it represses iron uptake by binding to IRO Box sequences upstream of RirA-regulated genes. Under low iron and/or aerobic conditions, [4Fe-4S] RirA undergoes cluster conversion/degradation to apo-RirA, which can no longer bind IRO Box sequences. Here, we apply time-resolved mass spectrometry and electron paramagnetic resonance spectroscopy to determine how the RirA cluster senses iron and O2. The data indicate that the key iron-sensing step is the O2-independent, reversible dissociation of Fe2+ from [4Fe-4S]2+ to form [3Fe-4S]0. The dissociation constant for this process was determined as Kd = ~3 µM, which is consistent with the sensing of 'free' iron in the cytoplasm. O2-sensing occurs through enhanced cluster degradation under aerobic conditions, via O2-mediated oxidation of the [3Fe-4S]0 intermediate to form [3Fe-4S]1+. This work provides a detailed mechanistic/functional view of an iron-responsive regulator.
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Affiliation(s)
- Ma Teresa Pellicer Martinez
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Melissa YY Stewart
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | | | - Andrew WB Johnston
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | - Myles R Cheesman
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Jonathan D Todd
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
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14
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Crack JC, Le Brun NE. Mass Spectrometric Identification of [4Fe–4S](NO)
x
Intermediates of Nitric Oxide Sensing by Regulatory Iron–Sulfur Cluster Proteins. Chemistry 2019; 25:3675-3684. [DOI: 10.1002/chem.201806113] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Jason C. Crack
- Centre for Molecular and Structural BiochemistrySchool of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Nick E. Le Brun
- Centre for Molecular and Structural BiochemistrySchool of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
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15
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Volbeda A, Martinez MTP, Crack JC, Amara P, Gigarel O, Munnoch JT, Hutchings MI, Darnault C, Le Brun NE, Fontecilla-Camps JC. Crystal Structure of the Transcription Regulator RsrR Reveals a [2Fe-2S] Cluster Coordinated by Cys, Glu, and His Residues. J Am Chem Soc 2019; 141:2367-2375. [PMID: 30657661 DOI: 10.1021/jacs.8b10823] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The recently discovered Rrf2 family transcriptional regulator RsrR coordinates a [2Fe-2S] cluster. Remarkably, binding of the protein to RsrR-regulated promoter DNA sequences is switched on and off through the facile cycling of the [2Fe-2S] cluster between +2 and +1 states. Here, we report high resolution crystal structures of the RsrR dimer, revealing that the [2Fe-2S] cluster is asymmetrically coordinated across the RsrR monomer-monomer interface by two Cys residues from one subunit and His and Glu residues from the other. To our knowledge, this is the first example of a protein bound [Fe-S] cluster with three different amino acid side chains as ligands, and of Glu acting as ligand to a [2Fe-2S] cluster. Analyses of RsrR structures revealed a conformational change, centered on Trp9, which results in a significant shift in the DNA-binding helix-turn-helix region.
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Affiliation(s)
- Anne Volbeda
- Université Grenoble Alpes, CEA, CNRS , IBS , Metalloproteins Unit, F-38044 Grenoble , France
| | - Ma Teresa Pellicer Martinez
- Centre for Molecular and Structural Biochemistry, School of Chemistry , University of East Anglia , Norwich Research Park, Norwich NR4 7TJ , United Kingdom
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry , University of East Anglia , Norwich Research Park, Norwich NR4 7TJ , United Kingdom
| | - Patricia Amara
- Université Grenoble Alpes, CEA, CNRS , IBS , Metalloproteins Unit, F-38044 Grenoble , France
| | - Océane Gigarel
- Université Grenoble Alpes, CEA, CNRS , IBS , Metalloproteins Unit, F-38044 Grenoble , France
| | - John T Munnoch
- School of Biological Sciences , University of East Anglia , Norwich Research Park, Norwich NR4 7TJ , United Kingdom
| | - Matthew I Hutchings
- School of Biological Sciences , University of East Anglia , Norwich Research Park, Norwich NR4 7TJ , United Kingdom
| | - Claudine Darnault
- Université Grenoble Alpes, CEA, CNRS , IBS , Metalloproteins Unit, F-38044 Grenoble , France
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry , University of East Anglia , Norwich Research Park, Norwich NR4 7TJ , United Kingdom
| | - Juan C Fontecilla-Camps
- Université Grenoble Alpes, CEA, CNRS , IBS , Metalloproteins Unit, F-38044 Grenoble , France
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16
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Crack JC, Stewart MYY, Le Brun NE. Generation of 34S-substituted protein-bound [4Fe-4S] clusters using 34S-L-cysteine. Biol Methods Protoc 2019; 4:bpy015. [PMID: 32395620 PMCID: PMC7200944 DOI: 10.1093/biomethods/bpy015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/03/2018] [Accepted: 12/10/2018] [Indexed: 01/30/2023] Open
Abstract
The ability to specifically label the sulphide ions of protein-bound iron-sulphur (FeS) clusters with 34S isotope greatly facilitates structure-function studies. In particular, it provides insight when using either spectroscopic techniques that probe cluster-associated vibrations, or non-denaturing mass spectrometry, where the ∼+2 Da average increase per sulphide enables unambiguous assignment of the FeS cluster and, where relevant, its conversion/degradation products. Here, we employ a thermostable homologue of the O-acetyl-l-serine sulfhydrylase CysK to generate 34S-substituted l-cysteine and subsequently use it as a substrate for the l-cysteine desulfurase NifS to gradually supply 34S2- for in vitro FeS cluster assembly in an otherwise standard cluster reconstitution protocol.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR47 TJ, UK
| | - Melissa Y Y Stewart
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR47 TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR47 TJ, UK
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17
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Abstract
SIGNIFICANCE Iron-sulfur cluster proteins carry out multiple functions, including as regulators of gene transcription/translation in response to environmental stimuli. In all known cases, the cluster acts as the sensory module, where the inherent reactivity/fragility of iron-sulfur clusters with small/redox-active molecules is exploited to effect conformational changes that modulate binding to DNA regulatory sequences. This promotes an often substantial reprogramming of the cellular proteome that enables the organism or cell to adapt to, or counteract, its changing circumstances. Recent Advances: Significant progress has been made recently in the structural and mechanistic characterization of iron-sulfur cluster regulators and, in particular, the O2 and NO sensor FNR, the NO sensor NsrR, and WhiB-like proteins of Actinobacteria. These are the main focus of this review. CRITICAL ISSUES Striking examples of how the local environment controls the cluster sensitivity and reactivity are now emerging, but the basis for this is not yet fully understood for any regulatory family. FUTURE DIRECTIONS Characterization of iron-sulfur cluster regulators has long been hampered by a lack of high-resolution structural data. Although this still presents a major future challenge, recent advances now provide a firm foundation for detailed understanding of how a signal is transduced to effect gene regulation. This requires the identification of often unstable intermediate species, which are difficult to detect and may be hard to distinguish using traditional techniques. Novel approaches will be required to solve these problems.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia , Norwich Research Park, Norwich, United Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia , Norwich Research Park, Norwich, United Kingdom
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18
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Crack JC, Hamilton CJ, Le Brun NE. Mass spectrometric detection of iron nitrosyls, sulfide oxidation and mycothiolation during nitrosylation of the NO sensor [4Fe-4S] NsrR. Chem Commun (Camb) 2018; 54:5992-5995. [PMID: 29790499 PMCID: PMC5994877 DOI: 10.1039/c8cc01339j] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Identification of RRE-type iron-nitrosyl species formed upon nitrosylation of [4Fe–4S] NsrR.
The bacterial nitric oxide (NO)-sensing transcriptional regulator NsrR binds a [4Fe–4S] cluster that enables DNA-binding and thus repression of the cell's NO stress response. Upon exposure to NO, the cluster undergoes a complex nitrosylation reaction resulting in a mixture of iron-nitrosyl species, which spectroscopic studies have indicated are similar to well characterized low molecular weight dinitrosyl iron complex (DNIC), Roussin's Red Ester (RRE) and Roussin's Black Salt (RBS). Here we report mass spectrometric studies that enable the unambiguous identification of NsrR-bound RRE-type species, including a persulfide bound form that results from the oxidation of cluster sulfide. In the presence of the low molecular weight thiols glutathione and mycothiol, glutathionylated and mycothiolated forms of NsrR were readily formed.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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19
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Adinolfi S, Puglisi R, Crack JC, Iannuzzi C, Dal Piaz F, Konarev PV, Svergun DI, Martin S, Le Brun NE, Pastore A. The Molecular Bases of the Dual Regulation of Bacterial Iron Sulfur Cluster Biogenesis by CyaY and IscX. Front Mol Biosci 2018; 4:97. [PMID: 29457004 PMCID: PMC5801593 DOI: 10.3389/fmolb.2017.00097] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 12/22/2017] [Indexed: 12/11/2022] Open
Abstract
IscX (or YfhJ) is a protein of unknown function which takes part in the iron-sulfur cluster assembly machinery, a highly specialized and essential metabolic pathway. IscX binds to iron with low affinity and interacts with IscS, the desulfurase central to cluster assembly. Previous studies have suggested a competition between IscX and CyaY, the bacterial ortholog of frataxin, for the same binding surface of IscS. This competition could suggest a link between the two proteins with a functional significance. Using a hybrid approach based on nuclear magnetic resonance, small angle scattering and biochemical methods, we show here that IscX is a modulator of the inhibitory properties of CyaY: by competing for the same site on IscS, the presence of IscX rescues the rates of enzymatic cluster formation which are inhibited by CyaY. The effect is stronger at low iron concentrations, whereas it becomes negligible at high iron concentrations. These results strongly suggest the mechanism of the dual regulation of iron sulfur cluster assembly under the control of iron as the effector.
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Affiliation(s)
| | - Rita Puglisi
- The Wohl Institute, King's College London, London, United Kingdom
| | - Jason C Crack
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Clara Iannuzzi
- The Wohl Institute, King's College London, London, United Kingdom.,DBBGP, Università degli Studi della Campania "L. Vanvitelli,", Naples, Italy
| | - Fabrizio Dal Piaz
- Dipartimento di Medicina, Chirurgia e Odontoiatria "Scuola Medica Salernitana"/DIPMED, Universita' di Salerno, Fisciano, Italy
| | - Petr V Konarev
- A.V. Shubnikov Institute of Crystallography of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Moscow, Russia.,National Research Centre "Kurchatov Institute, ", Moscow, Russia
| | | | | | - Nick E Le Brun
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Annalisa Pastore
- The Wohl Institute, King's College London, London, United Kingdom.,Department of Molecular Medicine, University of Pavia, Pavia, Italy
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20
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Abstract
SIGNIFICANCE Iron-sulfur cluster proteins carry out a wide range of functions, including as regulators of gene transcription/translation in response to environmental stimuli. In all known cases, the cluster acts as the sensory module, where the inherent reactivity/fragility of iron-sulfur clusters towards small/redox active molecules is exploited to effect conformational changes that modulate binding to DNA regulatory sequences. This promotes an often substantial re-programming of the cellular proteome that enables the organism or cell to adapt to, or counteract, its changing circumstances. Recent Advances. Significant progress has been made recently in the structural and mechanistic characterization of iron-sulfur cluster regulators and, in particular, the O2 and NO sensor FNR, the NO sensor NsrR, and WhiB-like proteins of Actinobacteria. These are the main focus of this review. CRITICAL ISSUES Striking examples of how the local environment controls the cluster sensitivity and reactivity are now emerging, but the basis for this is not yet fully understood for any regulatory family. FUTURE DIRECTIONS Characterization of iron-sulfur cluster regulators has long been hampered by a lack of high resolution structural data. Though this still presents a major future challenge, recent advances now provide a firm foundation for detailed understanding of how a signal is transduced to effect gene regulation. This requires the identification of often unstable intermediate species, which are difficult to detect and may be hard to distinguish using traditional techniques. Novel approaches will be required to solve these problems.
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Affiliation(s)
- Jason C Crack
- School of Chemistry , University of East Anglia , Norwich, United Kingdom of Great Britain and Northern Ireland , NR4 7TJ ;
| | - Nick E Le Brun
- University of East Anglia, School of Chemistry , University plain , Norwich, United Kingdom of Great Britain and Northern Ireland , NR4 7TJ ;
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21
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Smith LJ, Bochkareva A, Rolfe MD, Hunt DM, Kahramanoglou C, Braun Y, Rodgers A, Blockley A, Coade S, Lougheed KEA, Hafneh NA, Glenn SM, Crack JC, Le Brun NE, Saldanha JW, Makarov V, Nobeli I, Arnvig K, Mukamolova GV, Buxton RS, Green J. Cmr is a redox-responsive regulator of DosR that contributes to M. tuberculosis virulence. Nucleic Acids Res 2017; 45:6600-6612. [PMID: 28482027 PMCID: PMC5499769 DOI: 10.1093/nar/gkx406] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 04/28/2017] [Indexed: 12/05/2022] Open
Abstract
Mycobacterium tuberculosis (MTb) is the causative agent of pulmonary tuberculosis (TB). MTb colonizes the human lung, often entering a non-replicating state before progressing to life-threatening active infections. Transcriptional reprogramming is essential for TB pathogenesis. In vitro, Cmr (a member of the CRP/FNR super-family of transcription regulators) bound at a single DNA site to act as a dual regulator of cmr transcription and an activator of the divergent rv1676 gene. Transcriptional profiling and DNA-binding assays suggested that Cmr directly represses dosR expression. The DosR regulon is thought to be involved in establishing latent tuberculosis infections in response to hypoxia and nitric oxide. Accordingly, DNA-binding by Cmr was severely impaired by nitrosation. A cmr mutant was better able to survive a nitrosative stress challenge but was attenuated in a mouse aerosol infection model. The complemented mutant exhibited a ∼2-fold increase in cmr expression, which led to increased sensitivity to nitrosative stress. This, and the inability to restore wild-type behaviour in the infection model, suggests that precise regulation of the cmr locus, which is associated with Region of Difference 150 in hypervirulent Beijing strains of Mtb, is important for TB pathogenesis.
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Affiliation(s)
- Laura J Smith
- Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.,School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK
| | | | - Matthew D Rolfe
- Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Debbie M Hunt
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Christina Kahramanoglou
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Yvonne Braun
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Angela Rodgers
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Alix Blockley
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Stephen Coade
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Kathryn E A Lougheed
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Nor Azian Hafneh
- Department of Infection, Immunity and Inflammation, University of Leicester, University Road, Leicester LE1 9HN, UK
| | - Sarah M Glenn
- Department of Infection, Immunity and Inflammation, University of Leicester, University Road, Leicester LE1 9HN, UK
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
| | - José W Saldanha
- Division of Mathematical Biology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Vadim Makarov
- A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Irene Nobeli
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Kristine Arnvig
- Institute for Structural and Molecular Biology, University College London, London WC1E 6BT, UK
| | - Galina V Mukamolova
- Department of Infection, Immunity and Inflammation, University of Leicester, University Road, Leicester LE1 9HN, UK
| | - Roger S Buxton
- Division of Mycobacterial Research, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Jeffrey Green
- Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
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22
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Pellicer Martinez MT, Martinez AB, Crack JC, Holmes JD, Svistunenko DA, Johnston AWB, Cheesman MR, Todd JD, Le Brun NE. Sensing iron availability via the fragile [4Fe-4S] cluster of the bacterial transcriptional repressor RirA. Chem Sci 2017; 8:8451-8463. [PMID: 29619193 PMCID: PMC5863699 DOI: 10.1039/c7sc02801f] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/20/2017] [Indexed: 01/02/2023] Open
Abstract
The global iron regulator RirA controls transcription of iron metabolism genes via the binding of a fragile [4Fe–4S] cluster.
Rhizobial iron regulator A (RirA) is a global regulator of iron homeostasis in many nitrogen-fixing Rhizobia and related species of α-proteobacteria. It belongs to the widespread Rrf2 super-family of transcriptional regulators and features three conserved Cys residues that characterise the binding of an iron–sulfur cluster in other Rrf2 family regulators. Here we report biophysical studies demonstrating that RirA contains a [4Fe–4S] cluster, and that this form of the protein binds RirA-regulated DNA, consistent with its function as a repressor of expression of many genes involved in iron uptake. Under low iron conditions, [4Fe–4S] RirA undergoes a cluster conversion reaction resulting in a [2Fe–2S] form, which exhibits much lower affinity for DNA. Under prolonged low iron conditions, the [2Fe–2S] cluster degrades to apo-RirA, which does not bind DNA and can no longer function as a repressor of the cell's iron-uptake machinery. [4Fe–4S] RirA was also found to be sensitive to O2, suggesting that both iron and O2 are important signals for iron metabolism. Consistent with this, in vivo data showed that expression of RirA-regulated genes is also affected by O2. These data lead us to propose a novel regulatory model for iron homeostasis, in which RirA senses iron via the incorporation of a fragile iron–sulfur cluster that is sensitive to iron and O2 concentrations.
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Affiliation(s)
- Ma Teresa Pellicer Martinez
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK . ; ; Tel: +44 1603 592699
| | - Ana Bermejo Martinez
- School of Biological Sciences , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK . ; ; Tel: +44 1603 592699
| | - John D Holmes
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK . ; ; Tel: +44 1603 592699
| | - Dimitri A Svistunenko
- School of Biological Sciences , University of Essex , Wivenhoe Park , Colchester CO4 3SQ , UK
| | - Andrew W B Johnston
- School of Biological Sciences , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK
| | - Myles R Cheesman
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK . ; ; Tel: +44 1603 592699
| | - Jonathan D Todd
- School of Biological Sciences , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK . ; ; Tel: +44 1603 592699
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23
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Bastow EL, Bych K, Crack JC, Le Brun NE, Balk J. NBP35 interacts with DRE2 in the maturation of cytosolic iron-sulphur proteins in Arabidopsis thaliana. Plant J 2017; 89:590-600. [PMID: 27801963 PMCID: PMC5324674 DOI: 10.1111/tpj.13409] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [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: 08/19/2016] [Revised: 10/04/2016] [Accepted: 10/27/2016] [Indexed: 05/23/2023]
Abstract
Proteins of the cytosolic pathway for iron-sulphur (FeS) cluster assembly are conserved, except that plants lack a gene for CFD1 (Cytosolic FeS cluster Deficient 1). This poses the question of how NBP35 (Nucleotide-Binding Protein 35 kDa), the heteromeric partner of CFD1 in metazoa, functions on its own in plants. Firstly, we created viable mutant alleles of NBP35 in Arabidopsis to overcome embryo lethality of previously reported knockout mutations. RNAi knockdown lines with less than 30% NBP35 protein surprisingly showed no developmental or biochemical differences to wild-type. Substitution of Cys14 to Ala, which destabilized the N-terminal Fe4 S4 cluster in vitro, caused mild growth defects and a significant decrease in the activity of cytosolic FeS enzymes such as aconitase and aldehyde oxidases. The DNA glycosylase ROS1 was only partially decreased in activity and xanthine dehydrogenase not at all. Plants with strongly depleted NBP35 protein in combination with Cys14 to Ala substitution had distorted leaf development and decreased FeS enzyme activities. To find protein interaction partners of NBP35, a yeast-two-hybrid screen was carried out that identified NBP35 and DRE2 (Derepressed for Ribosomal protein S14 Expression). NBP35 is known to form a dimer, and DRE2 acts upstream in the cytosolic FeS protein assembly pathway. The NBP35-DRE2 interaction was not disrupted by Cys14 to Ala substitution. Our results show that NBP35 has a function in the maturation of FeS proteins that is conserved in plants, and is closely allied to the function of DRE2.
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Affiliation(s)
- Emma L. Bastow
- John Innes CentreNorwichNR4 7UHUK
- University of East AngliaNorwichNR4 7TJUK
| | - Katrine Bych
- Department of Plant SciencesUniversity of CambridgeCambridgeCB2 3EAUK
- Present address: Glycom A/SDK – 2800 Kgs.LyngbyDenmark
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24
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Serrano PN, Wang H, Crack JC, Prior C, Hutchings MI, Thomson AJ, Kamali S, Yoda Y, Zhao J, Hu MY, Alp EE, Oganesyan VS, Le Brun NE, Cramer SP. Nitrosylation of Nitric-Oxide-Sensing Regulatory Proteins Containing [4Fe-4S] Clusters Gives Rise to Multiple Iron-Nitrosyl Complexes. Angew Chem Int Ed Engl 2016; 55:14575-14579. [PMID: 27778474 PMCID: PMC5204455 DOI: 10.1002/anie.201607033] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/05/2016] [Indexed: 12/13/2022]
Abstract
The reaction of protein-bound iron-sulfur (Fe-S) clusters with nitric oxide (NO) plays key roles in NO-mediated toxicity and signaling. Elucidation of the mechanism of the reaction of NO with DNA regulatory proteins that contain Fe-S clusters has been hampered by a lack of information about the nature of the iron-nitrosyl products formed. Herein, we report nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT) calculations that identify NO reaction products in WhiD and NsrR, regulatory proteins that use a [4Fe-4S] cluster to sense NO. This work reveals that nitrosylation yields multiple products structurally related to Roussin's Red Ester (RRE, [Fe2 (NO)4 (Cys)2 ]) and Roussin's Black Salt (RBS, [Fe4 (NO)7 S3 ]. In the latter case, the absence of 32 S/34 S shifts in the Fe-S region of the NRVS spectra suggest that a new species, Roussin's Black Ester (RBE), may be formed, in which one or more of the sulfide ligands is replaced by Cys thiolates.
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Affiliation(s)
| | - Hongxin Wang
- Department of ChemistryUniversity of CaliforniaDavisCA95616USA
- Physical Biosciences DivisionLawrence Berkeley National LaboratoryBerkeleyCA94720USA
| | - Jason C. Crack
- Centre for Molecular and Structural BiochemistrySchool of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Christopher Prior
- Centre for Molecular and Structural BiochemistrySchool of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | | | - Andrew J. Thomson
- Centre for Molecular and Structural BiochemistrySchool of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Saeed Kamali
- University of Tennessee Space InstituteTullahomeTN37388-9700USA
| | - Yoshitaka Yoda
- Research and Utilization DivisionSPring-8/JASRI1-1-1 Kouto, SayoHyogo679-5198Japan
| | - Jiyong Zhao
- Advanced Photon SourceArgonne National LaboratoryArgonneIL60439USA
| | - Michael Y. Hu
- Advanced Photon SourceArgonne National LaboratoryArgonneIL60439USA
| | - Ercan E. Alp
- Advanced Photon SourceArgonne National LaboratoryArgonneIL60439USA
| | - Vasily S. Oganesyan
- Centre for Molecular and Structural BiochemistrySchool of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Nick E. Le Brun
- Centre for Molecular and Structural BiochemistrySchool of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Stephen P. Cramer
- Department of ChemistryUniversity of CaliforniaDavisCA95616USA
- Physical Biosciences DivisionLawrence Berkeley National LaboratoryBerkeleyCA94720USA
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25
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Serrano PN, Wang H, Crack JC, Prior C, Hutchings MI, Thomson AJ, Kamali S, Yoda Y, Zhao J, Hu MY, Alp EE, Oganesyan VS, Le Brun NE, Cramer SP. Nitrosylation of Nitric-Oxide-Sensing Regulatory Proteins Containing [4Fe-4S] Clusters Gives Rise to Multiple Iron-Nitrosyl Complexes. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201607033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Hongxin Wang
- Department of Chemistry; University of California; Davis CA 95616 USA
- Physical Biosciences Division; Lawrence Berkeley National Laboratory; Berkeley CA 94720 USA
| | - Jason C. Crack
- Centre for Molecular and Structural Biochemistry; School of Chemistry; University of East Anglia; Norwich Research Park Norwich NR4 7TJ UK
| | - Christopher Prior
- Centre for Molecular and Structural Biochemistry; School of Chemistry; University of East Anglia; Norwich Research Park Norwich NR4 7TJ UK
| | | | - Andrew J. Thomson
- Centre for Molecular and Structural Biochemistry; School of Chemistry; University of East Anglia; Norwich Research Park Norwich NR4 7TJ UK
| | - Saeed Kamali
- University of Tennessee Space Institute; Tullahome TN 37388-9700 USA
| | - Yoshitaka Yoda
- Research and Utilization Division; SPring-8/JASRI; 1-1-1 Kouto, Sayo Hyogo 679-5198 Japan
| | - Jiyong Zhao
- Advanced Photon Source; Argonne National Laboratory; Argonne IL 60439 USA
| | - Michael Y. Hu
- Advanced Photon Source; Argonne National Laboratory; Argonne IL 60439 USA
| | - Ercan E. Alp
- Advanced Photon Source; Argonne National Laboratory; Argonne IL 60439 USA
| | - Vasily S. Oganesyan
- Centre for Molecular and Structural Biochemistry; School of Chemistry; University of East Anglia; Norwich Research Park Norwich NR4 7TJ UK
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry; School of Chemistry; University of East Anglia; Norwich Research Park Norwich NR4 7TJ UK
| | - Stephen P. Cramer
- Department of Chemistry; University of California; Davis CA 95616 USA
- Physical Biosciences Division; Lawrence Berkeley National Laboratory; Berkeley CA 94720 USA
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26
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Crack JC, Svistunenko DA, Munnoch J, Thomson AJ, Hutchings MI, Le Brun NE. Differentiated, Promoter-specific Response of [4Fe-4S] NsrR DNA Binding to Reaction with Nitric Oxide. J Biol Chem 2016; 291:8663-72. [PMID: 26887943 PMCID: PMC4861436 DOI: 10.1074/jbc.m115.693192] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Indexed: 12/19/2022] Open
Abstract
NsrR is an iron-sulfur cluster protein that regulates the nitric oxide (NO) stress response of many bacteria. NsrR from Streptomyces coelicolor regulates its own expression and that of only two other genes, hmpA1 and hmpA2, which encode HmpA enzymes predicted to detoxify NO. NsrR binds promoter DNA with high affinity only when coordinating a [4Fe-4S] cluster. Here we show that reaction of [4Fe-4S] NsrR with NO affects DNA binding differently depending on the gene promoter. Binding to the hmpA2 promoter was abolished at ∼2 NO per cluster, although for the hmpA1 and nsrR promoters, ∼4 and ∼8 NO molecules, respectively, were required to abolish DNA binding. Spectroscopic and kinetic studies of the NO reaction revealed a rapid, multi-phase, non-concerted process involving up to 8–10 NO molecules per cluster, leading to the formation of several iron-nitrosyl species. A distinct intermediate was observed at ∼2 NO per cluster, along with two further intermediates at ∼4 and ∼6 NO. The NsrR nitrosylation reaction was not significantly affected by DNA binding. These results show that NsrR regulates different promoters in response to different concentrations of NO. Spectroscopic evidence indicates that this is achieved by different NO-FeS complexes.
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Affiliation(s)
- Jason C Crack
- From the Centre for Molecular and Structural Biochemistry, School of Chemistry, and
| | - Dimitri A Svistunenko
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - John Munnoch
- the School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ and
| | - Andrew J Thomson
- From the Centre for Molecular and Structural Biochemistry, School of Chemistry, and
| | - Matthew I Hutchings
- the School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ and
| | - Nick E Le Brun
- From the Centre for Molecular and Structural Biochemistry, School of Chemistry, and
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27
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Crack JC, Hutchings MI, Thomson AJ, Le Brun NE. Biochemical properties of Paracoccus denitrificans FnrP: reactions with molecular oxygen and nitric oxide. J Biol Inorg Chem 2016; 21:71-82. [PMID: 26790880 PMCID: PMC4771820 DOI: 10.1007/s00775-015-1326-7] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/23/2015] [Indexed: 02/04/2023]
Abstract
In Paracoccus denitrificans, three CRP/FNR family regulatory proteins, NarR, NnrR and FnrP, control the switch between aerobic and anaerobic (denitrification) respiration. FnrP is a [4Fe–4S] cluster-containing homologue of the archetypal O2 sensor FNR from E. coli and accordingly regulates genes encoding aerobic and anaerobic respiratory enzymes in response to O2, and also NO, availability. Here we show that FnrP undergoes O2-driven [4Fe–4S] to [2Fe–2S] cluster conversion that involves up to 2 O2 per cluster, with significant oxidation of released cluster sulfide to sulfane observed at higher O2 concentrations. The rate of the cluster reaction was found to be ~sixfold lower than that of E. coli FNR, suggesting that FnrP can remain transcriptionally active under microaerobic conditions. This is consistent with a role for FnrP in activating expression of the high O2 affinity cytochrome c oxidase under microaerobic conditions. Cluster conversion resulted in dissociation of the transcriptionally active FnrP dimer into monomers. Therefore, along with E. coli FNR, FnrP belongs to the subset of FNR proteins in which cluster type is correlated with association state. Interestingly, two key charged residues, Arg140 and Asp154, that have been shown to play key roles in the monomer–dimer equilibrium in E. coli FNR are not conserved in FnrP, indicating that different protomer interactions are important for this equilibrium. Finally, the FnrP [4Fe–4S] cluster is shown to undergo reaction with multiple NO molecules, resulting in iron nitrosyl species and dissociation into monomers.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Matthew I Hutchings
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Andrew J Thomson
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
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28
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Ibrahim SA, Crack JC, Rolfe MD, Borrero-de Acuña JM, Thomson AJ, Le Brun NE, Schobert M, Stapleton MR, Green J. Three Pseudomonas putida FNR Family Proteins with Different Sensitivities to O2. J Biol Chem 2015; 290:16812-23. [PMID: 25971977 PMCID: PMC4505428 DOI: 10.1074/jbc.m115.654079] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Indexed: 12/24/2022] Open
Abstract
The Escherichia coli fumarate-nitrate reduction regulator (FNR) protein is the paradigm for bacterial O2-sensing transcription factors. However, unlike E. coli, some bacterial species possess multiple FNR proteins that presumably have evolved to fulfill distinct roles. Here, three FNR proteins (ANR, PP_3233, and PP_3287) from a single bacterial species, Pseudomonas putida KT2440, have been analyzed. Under anaerobic conditions, all three proteins had spectral properties resembling those of [4Fe-4S] proteins. The reactivity of the ANR [4Fe-4S] cluster with O2 was similar to that of E. coli FNR, and during conversion to the apo-protein, via a [2Fe-2S] intermediate, cluster sulfur was retained. Like ANR, reconstituted PP_3233 and PP_3287 were converted to [2Fe-2S] forms when exposed to O2, but their [4Fe-4S] clusters reacted more slowly. Transcription from an FNR-dependent promoter with a consensus FNR-binding site in P. putida and E. coli strains expressing only one FNR protein was consistent with the in vitro responses to O2. Taken together, the experimental results suggest that the local environments of the iron-sulfur clusters in the different P. putida FNR proteins influence their reactivity with O2, such that ANR resembles E. coli FNR and is highly responsive to low concentrations of O2, whereas PP_3233 and PP_3287 have evolved to be less sensitive to O2.
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Affiliation(s)
- Susan A Ibrahim
- From the Krebs Institute, Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | - Jason C Crack
- the Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom, and
| | - Matthew D Rolfe
- From the Krebs Institute, Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | | | - Andrew J Thomson
- the Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom, and
| | - Nick E Le Brun
- the Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom, and
| | - Max Schobert
- Institut für Mikrobiologie, Technische Universität, D-38106 Braunschweig, Germany
| | - Melanie R Stapleton
- From the Krebs Institute, Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | - Jeffrey Green
- From the Krebs Institute, Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom,
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29
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Crack JC, Munnoch J, Dodd EL, Knowles F, Al Bassam MM, Kamali S, Holland AA, Cramer SP, Hamilton CJ, Johnson MK, Thomson AJ, Hutchings MI, Le Brun NE. NsrR from Streptomyces coelicolor is a nitric oxide-sensing [4Fe-4S] cluster protein with a specialized regulatory function. J Biol Chem 2015; 290:12689-704. [PMID: 25771538 PMCID: PMC4432287 DOI: 10.1074/jbc.m115.643072] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Indexed: 12/31/2022] Open
Abstract
The Rrf2 family transcription factor NsrR controls expression of genes in a wide range of bacteria in response to nitric oxide (NO). The precise form of the NO-sensing module of NsrR is the subject of controversy because NsrR proteins containing either [2Fe-2S] or [4Fe-4S] clusters have been observed previously. Optical, Mössbauer, resonance Raman spectroscopies and native mass spectrometry demonstrate that Streptomyces coelicolor NsrR (ScNsrR), previously reported to contain a [2Fe-2S] cluster, can be isolated containing a [4Fe-4S] cluster. ChIP-seq experiments indicated that the ScNsrR regulon is small, consisting of only hmpA1, hmpA2, and nsrR itself. The hmpA genes encode NO-detoxifying flavohemoglobins, indicating that ScNsrR has a specialized regulatory function focused on NO detoxification and is not a global regulator like some NsrR orthologues. EMSAs and DNase I footprinting showed that the [4Fe-4S] form of ScNsrR binds specifically and tightly to an 11-bp inverted repeat sequence in the promoter regions of the identified target genes and that DNA binding is abolished following reaction with NO. Resonance Raman data were consistent with cluster coordination by three Cys residues and one oxygen-containing residue, and analysis of ScNsrR variants suggested that highly conserved Glu-85 may be the fourth ligand. Finally, we demonstrate that some low molecular weight thiols, but importantly not physiologically relevant thiols, such as cysteine and an analogue of mycothiol, bind weakly to the [4Fe-4S] cluster, and exposure of this bound form to O2 results in cluster conversion to the [2Fe-2S] form, which does not bind to DNA. These data help to account for the observation of [2Fe-2S] forms of NsrR.
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Affiliation(s)
- Jason C Crack
- From the Centre for Molecular and Structural Biochemistry, School of Chemistry
| | | | - Erin L Dodd
- From the Centre for Molecular and Structural Biochemistry, School of Chemistry
| | | | | | - Saeed Kamali
- the Department of Chemistry, University of California, Davis, California 95616, and
| | - Ashley A Holland
- the Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602
| | - Stephen P Cramer
- the Department of Chemistry, University of California, Davis, California 95616, and
| | - Chris J Hamilton
- the School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Michael K Johnson
- the Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602
| | - Andrew J Thomson
- From the Centre for Molecular and Structural Biochemistry, School of Chemistry
| | | | - Nick E Le Brun
- From the Centre for Molecular and Structural Biochemistry, School of Chemistry,
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30
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Crack JC, Green J, Thomson AJ, Brun NEL. Iron-sulfur clusters as biological sensors: the chemistry of reactions with molecular oxygen and nitric oxide. Acc Chem Res 2014; 47:3196-205. [PMID: 25262769 DOI: 10.1021/ar5002507] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Iron-sulfur cluster proteins exhibit a range of physicochemical properties that underpin their functional diversity in biology, which includes roles in electron transfer, catalysis, and gene regulation. Transcriptional regulators that utilize iron-sulfur clusters are a growing group that exploit the redox and coordination properties of the clusters to act as sensors of environmental conditions including O2, oxidative and nitrosative stress, and metabolic nutritional status. To understand the mechanism by which a cluster detects such analytes and then generates modulation of DNA-binding affinity, we have undertaken a combined strategy of in vivo and in vitro studies of a range of regulators. In vitro studies of iron-sulfur cluster proteins are particularly challenging because of the inherent reactivity and fragility of the cluster, often necessitating strict anaerobic conditions for all manipulations. Nevertheless, and as discussed in this Account, significant progress has been made over the past decade in studies of O2-sensing by the fumarate and nitrate reduction (FNR) regulator and, more recently, nitric oxide (NO)-sensing by WhiB-like (Wbl) and FNR proteins. Escherichia coli FNR binds a [4Fe-4S] cluster under anaerobic conditions leading to a DNA-binding dimeric form. Exposure to O2 converts the cluster to a [2Fe-2S] form, leading to protein monomerization and hence loss of DNA binding ability. Spectroscopic and kinetic studies have shown that the conversion proceeds via at least two steps and involves a [3Fe-4S](1+) intermediate. The second step involves the release of two bridging sulfide ions from the cluster that, unusually, are not released into solution but rather undergo oxidation to sulfane (S(0)) subsequently forming cysteine persulfides that then coordinate the [2Fe-2S] cluster. Studies of other [4Fe-4S] cluster proteins that undergo oxidative cluster conversion indicate that persulfide formation and coordination may be more common than previously recognized. This remarkable feature suggested that the original [4Fe-4S] cluster can be restored using persulfide as the source of sulfide ion. We have demonstrated that only iron and a source of electrons are required to promote efficient conversion back from the [2Fe-2S] to the [4Fe-4S] form. We propose this as a novel in vivo repair mechanism that does not require the intervention of an iron-sulfur cluster biogenesis pathway. A number of iron-sulfur regulators have evolved to function as sensors of NO. Although it has long been known that the iron-sulfur clusters of many phylogenetically unrelated proteins are vulnerable to attack by NO, our recent studies of Wbl proteins and FNR have provided new insights into the mechanism of cluster nitrosylation, which overturn the commonly accepted view that the product is solely a mononuclear iron dinitrosyl complex (known as a DNIC). The major reaction is a rapid, multiphase process involving stepwise addition of up to eight NO molecules per [4Fe-4S] cluster. The major iron nitrosyl product is EPR silent and has optical characteristics similar to Roussin's red ester, [Fe2(NO)4(RS)2] (RRE), although a species similar to Roussin's black salt, [Fe4(NO)7(S)3](-) (RBS) cannot be ruled out. A major future challenge will be to clarify the nature of these species.
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Affiliation(s)
- Jason C. Crack
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Jeffrey Green
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
| | - Andrew J. Thomson
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Nick E. Le Brun
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
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Crack JC, Stapleton MR, Green J, Thomson AJ, Le Brun NE. Mechanism of [4Fe-4S](Cys)4 cluster nitrosylation is conserved among NO-responsive regulators. J Biol Chem 2013; 288:11492-502. [PMID: 23471974 DOI: 10.1074/jbc.m112.439901] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Fumarate nitrate reduction (FNR) regulator from Escherichia coli controls expression of >300 genes in response to O2 through reaction with its [4Fe-4S] cluster cofactor. FNR is the master switch for the transition between anaerobic and aerobic respiration. In response to physiological concentrations of nitric oxide (NO), FNR also regulates genes, including the nitrate reductase (nar) operon, a major source of endogenous cellular NO, and hmp, which encodes an NO-detoxifying enzyme. Here we show that the [4Fe-4S] cluster of FNR reacts rapidly in a multiphasic reaction with eight NO molecules. Oxidation of cluster sulfide ions (S(2-)) to sulfane (S(0)) occurs, some of which remains associated with the protein as Cys persulfide. The nitrosylation products are similar to a pair of dinuclear dinitrosyl iron complexes, [Fe(I)2(NO)4(Cys)2](0), known as Roussin's red ester. A similar reactivity with NO was reported for the Wbl family of [4Fe-4S]-containing proteins found only in actinomycetes, such as Streptomyces and Mycobacteria. These results show that NO reacts via a common mechanism with [4Fe-4S] clusters in phylogenetically unrelated regulatory proteins that, although coordinated by four Cys residues, have different cluster environments. The reactivity of E. coli FNR toward NO, in addition to its sensitivity toward O2, is part of a hierarchal network that monitors, and responds to, NO, both endogenously generated and exogenously derived.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
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Abstract
SIGNIFICANCE In recent years, bacterial iron-sulfur cluster proteins that function as regulators of gene transcription have emerged as a major new group. In all cases, the cluster acts as a sensor of the environment and enables the organism to adapt to the prevailing conditions. This can range from mounting a response to oxidative or nitrosative stress to switching between anaerobic and aerobic respiratory pathways. The sensitivity of these ancient cofactors to small molecule reactive oxygen and nitrogen species, in particular, makes them ideally suited to function as sensors. RECENT ADVANCES An important challenge is to obtain mechanistic and structural information about how these regulators function and, in particular, how the chemistry occurring at the cluster drives the subsequent regulatory response. For several regulators, including FNR, SoxR, NsrR, IscR, and Wbl proteins, major advances in understanding have been gained recently and these are reviewed here. CRITICAL ISSUES A common theme emerging from these studies is that the sensitivity and specificity of the cluster of each regulatory protein must be exquisitely controlled by the protein environment of the cluster. FUTURE DIRECTIONS A major future challenge is to determine, for a range of regulators, the key factors for achieving control of sensitivity/specificity. Such information will lead, eventually, to a system understanding of stress response, which often involves more than one regulator.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom
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Crack JC, Green J, Thomson AJ, Le Brun NE. Iron-sulfur cluster sensor-regulators. Curr Opin Chem Biol 2012; 16:35-44. [PMID: 22387135 DOI: 10.1016/j.cbpa.2012.02.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 01/13/2012] [Accepted: 02/08/2012] [Indexed: 10/28/2022]
Abstract
Regulatory proteins that contain an iron-sulfur cluster cofactor constitute a group that is growing both in number and importance, with a range of functions that include sensing of molecular oxygen, stress response, and iron regulation. In all cases, the cluster plays a central role, as a sensory module, in controlling the activity of the regulator. In some cases, the cluster is required for the protein to attain its regulatory form, while in others the active form requires loss or modification of the cluster. In this way, nature has exploited the inherent reactivity of iron-sulfur clusters. Here, we focus on recent advances that provide new insight into the remarkable chemistries exhibited by these regulators, and how they achieve the required levels of sensitivity and specificity.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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Facey PD, Sevcikova B, Novakova R, Hitchings MD, Crack JC, Kormanec J, Dyson PJ, Del Sol R. The dpsA gene of Streptomyces coelicolor: induction of expression from a single promoter in response to environmental stress or during development. PLoS One 2011; 6:e25593. [PMID: 21984935 PMCID: PMC3184153 DOI: 10.1371/journal.pone.0025593] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 09/07/2011] [Indexed: 11/24/2022] Open
Abstract
The DpsA protein plays a dual role in Streptomyces coelicolor, both as part of the stress response and contributing to nucleoid condensation during sporulation. Promoter mapping experiments indicated that dpsA is transcribed from a single, sigB-like dependent promoter. Expression studies implicate SigH and SigB as the sigma factors responsible for dpsA expression while the contribution of other SigB-like factors is indirect by means of controlling sigH expression. The promoter is massively induced in response to osmotic stress, in part due to its sensitivity to changes in DNA supercoiling. In addition, we determined that WhiB is required for dpsA expression, particularly during development. Gel retardation experiments revealed direct interaction between apoWhiB and the dpsA promoter region, providing the first evidence for a direct WhiB target in S. coelicolor.
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Affiliation(s)
- Paul D. Facey
- Institute of Life Science, College of Medicine, Swansea University, Swansea, United Kingdom
| | - Beatrica Sevcikova
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Renata Novakova
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Matthew D. Hitchings
- Institute of Life Science, College of Medicine, Swansea University, Swansea, United Kingdom
| | - Jason C. Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - Jan Kormanec
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Paul J. Dyson
- Institute of Life Science, College of Medicine, Swansea University, Swansea, United Kingdom
| | - Ricardo Del Sol
- Institute of Life Science, College of Medicine, Swansea University, Swansea, United Kingdom
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Crack JC, Smith LJ, Stapleton MR, Peck J, Watmough NJ, Buttner MJ, Buxton RS, Green J, Oganesyan VS, Thomson AJ, Le Brun NE. Mechanistic insight into the nitrosylation of the [4Fe-4S] cluster of WhiB-like proteins. J Am Chem Soc 2010; 133:1112-21. [PMID: 21182249 PMCID: PMC3117330 DOI: 10.1021/ja109581t] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
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The reactivity of protein bound iron−sulfur clusters with nitric oxide (NO) is well documented, but little is known about the actual mechanism of cluster nitrosylation. Here, we report studies of members of the Wbl family of [4Fe−4S] containing proteins, which play key roles in regulating developmental processes in actinomycetes, including Streptomyces and Mycobacteria, and have been shown to be NO responsive. Streptomyces coelicolor WhiD and Mycobacterium tuberculosis WhiB1 react extremely rapidly with NO in a multiphasic reaction involving, remarkably, 8 NO molecules per [4Fe−4S] cluster. The reaction is 104-fold faster than that observed with O2 and is by far the most rapid iron−sulfur cluster nitrosylation reaction reported to date. An overall stoichiometry of [Fe4S4(Cys)4]2− + 8NO → 2[FeI2(NO)4(Cys)2]0 + S2− + 3S0 has been established by determination of the sulfur products and their oxidation states. Kinetic analysis leads to a four-step mechanism that accounts for the observed NO dependence. DFT calculations suggest the possibility that the nitrosylation product is a novel cluster [FeI4(NO)8(Cys)4]0 derived by dimerization of a pair of Roussin’s red ester (RRE) complexes.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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Crack JC, den Hengst CD, Jakimowicz P, Subramanian S, Johnson MK, Buttner MJ, Thomson AJ, Le Brun NE. Characterization of [4Fe-4S]-containing and cluster-free forms of Streptomyces WhiD. Biochemistry 2010; 48:12252-64. [PMID: 19954209 DOI: 10.1021/bi901498v] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
WhiD, a member of the WhiB-like (Wbl) family of iron-sulfur proteins found exclusively within the actinomycetes, is required for the late stages of sporulation in Streptomyces coelicolor. Like all other Wbl proteins, WhiD has not so far been purified in a soluble form that contains a significant amount of cluster, and characterization has relied on cluster-reconstituted protein. Thus, a major goal in Wbl research is to obtain and characterize native protein containing iron-sulfur clusters. Here we report the analysis of S. coelicolor WhiD purified anaerobically from Escherichia coli as a soluble protein containing a single [4Fe-4S](2+) cluster ligated by four cysteines. Upon exposure to oxygen, spectral features associated with the [4Fe-4S] cluster were lost in a slow reaction that unusually yielded apo-WhiD directly without significant concentrations of cluster intermediates. This process was found to be highly pH dependent with an optimal stability observed between pH 7.0 and pH 8.0. Low molecular weight thiols, including a mycothiol analogue and thioredoxin, exerted a small but significant protective effect against WhiD cluster loss, an activity that could be of physiological importance. [4Fe-4S](2+) WhiD was found to react much more rapidly with superoxide than with either oxygen or hydrogen peroxide, which may also be of physiological significance. Loss of the [4Fe-4S] cluster to form apoprotein destabilized the protein fold significantly but did not lead to complete unfolding. Finally, apo-WhiD exhibited negligible activity in an insulin-based disulfide reductase assay, demonstrating that it does not function as a general protein disulfide reductase.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
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Green J, Crack JC, Thomson AJ, LeBrun NE. Bacterial sensors of oxygen. Curr Opin Microbiol 2009; 12:145-51. [DOI: 10.1016/j.mib.2009.01.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 01/19/2009] [Accepted: 01/22/2009] [Indexed: 12/23/2022]
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Tucker NP, Hicks MG, Clarke TA, Crack JC, Chandra G, Le Brun NE, Dixon R, Hutchings MI. The transcriptional repressor protein NsrR senses nitric oxide directly via a [2Fe-2S] cluster. PLoS One 2008; 3:e3623. [PMID: 18989365 PMCID: PMC2577008 DOI: 10.1371/journal.pone.0003623] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2008] [Accepted: 10/16/2008] [Indexed: 01/08/2023] Open
Abstract
The regulatory protein NsrR, a member of the Rrf2 family of transcription repressors, is specifically dedicated to sensing nitric oxide (NO) in a variety of pathogenic and non-pathogenic bacteria. It has been proposed that NO directly modulates NsrR activity by interacting with a predicted [Fe-S] cluster in the NsrR protein, but no experimental evidence has been published to support this hypothesis. Here we report the purification of NsrR from the obligate aerobe Streptomyces coelicolor. We demonstrate using UV-visible, near UV CD and EPR spectroscopy that the protein contains an NO-sensitive [2Fe-2S] cluster when purified from E. coli. Upon exposure of NsrR to NO, the cluster is nitrosylated, which results in the loss of DNA binding activity as detected by bandshift assays. Removal of the [2Fe-2S] cluster to generate apo-NsrR also resulted in loss of DNA binding activity. This is the first demonstration that NsrR contains an NO-sensitive [2Fe-2S] cluster that is required for DNA binding activity.
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Affiliation(s)
- Nicholas P. Tucker
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
- * E-mail: (NPT); (MIH)
| | - Matthew G. Hicks
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Thomas A. Clarke
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Jason C. Crack
- School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Nick E. Le Brun
- School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Matthew I. Hutchings
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
- School of Medicine, Health Policy and Practice, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
- * E-mail: (NPT); (MIH)
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Crack JC, Gaskell AA, Green J, Cheesman MR, Le Brun NE, Thomson AJ. Influence of the environment on the [4Fe-4S]2+ to [2Fe-2S]2+ cluster switch in the transcriptional regulator FNR. J Am Chem Soc 2008. [PMID: 18186637 DOI: 10.1021/ja077455] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In Escherichia coli, the switch between aerobic and anaerobic metabolism is primarily controlled by the fumarate and nitrate reduction transcriptional regulator FNR. In the absence of O2, FNR binds a [4Fe-4S]2+ cluster, generating a transcriptionally active dimeric form. Exposure to O2 results in the conversion of the cluster to a [2Fe-2S]2+ form, leading to dissociation of the protein into transcriptionally inactive monomers. The [4Fe-4S]2+ to [2Fe-2S]2+ cluster conversion proceeds in two steps. Step 1 involves the one-electron oxidation of the cluster, resulting in the release of Fe2+, generating a [3Fe-4S]1+ cluster intermediate, and a superoxide ion. In step 2, the cluster intermediate spontaneously rearranges to form the [2Fe-2S]2+ cluster, with the release of a Fe3+ ion and two sulfide ions. Here, we demonstrate that, in both native and reconstituted [4Fe-4S] FNR, the reaction environment and, in particular, the presence of Fe2+ and/or Fe3+ chelators can influence significantly the cluster conversion reaction. We demonstrate that while the rate of step 1 is largely insensitive to chelators, that of step 2 is significantly enhanced by both Fe2+ and Fe3+ chelators. We show that, for reactions in Fe3+-coordinating phosphate buffer, step 2 is enhanced to the extent that step 1 becomes the rate determining step and the [3Fe-4S]1+ intermediate is no longer detectable. Furthermore, Fe3+ released during this step is susceptible to reduction in the presence of Fe2+ chelators. This work, which may have significance for the in vivo FNR cluster conversion reaction in the cell cytoplasm, provides an explanation for apparently contradictory results reported from different laboratories.
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Affiliation(s)
- Jason C Crack
- Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, NR4 7TJ, UK
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Crack JC, Le Brun NE, Thomson AJ, Green J, Jervis AJ. Reactions of nitric oxide and oxygen with the regulator of fumarate and nitrate reduction, a global transcriptional regulator, during anaerobic growth of Escherichia coli. Methods Enzymol 2008; 437:191-209. [PMID: 18433630 DOI: 10.1016/s0076-6879(07)37011-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The Escherichia coli fumarate and nitrate reductase (FNR) regulator protein is an important transcriptional regulator that controls the expression of a large regulon of more than 100 genes in response to changes in oxygen availability. FNR is active when it acquires a [4Fe-4S](2+) cluster under anaerobic conditions. The presence of the [4Fe-4S](2+) cluster promotes protein dimerization and site-specific DNA binding, facilitating activation or repression of target promoters. Oxygen is sensed by the controlled disassembly of the [4Fe-4S](2+) cluster, ultimately resulting in inactive, monomeric, apo-FNR. The FNR [4Fe-4S](2+) cluster is also sensitive to nitric oxide, such that under anaerobic conditions the protein is inactivated by nitrosylation of the iron-sulfur cluster, yielding a mixture of monomeric and dimeric dinitrosyl-iron cysteine species. This chapter describes some of the methods used to produce active [4Fe-4S] FNR protein and investigates the reaction of the [4Fe-4S](2+) cluster with nitric oxide and oxygen in vitro.
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Affiliation(s)
- Jason C Crack
- Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, United Kingdom
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Gaskell AA, Crack JC, Kelemen GH, Hutchings MI, Le Brun NE. RsmA is an anti-sigma factor that modulates its activity through a [2Fe-2S] cluster cofactor. J Biol Chem 2007; 282:31812-20. [PMID: 17766240 DOI: 10.1074/jbc.m705160200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [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: 11/06/2022] Open
Abstract
The rsmA gene of Streptomyces coelicolor lies directly upstream of the gene encoding the group 3 sigma factor sigma(M). The RsmA protein is a putative member of the HATPase_c family of anti-sigma factors but is unusual in that it contains seven cysteine residues. Bacterial two-hybrid studies demonstrate that it interacts specifically with sigma(M), and in vitro studies of the purified proteins by native PAGE and transcription assays confirmed that they form a complex. Characterization of RsmA revealed that it binds ATP and that, as isolated, it contains significant quantities of iron and inorganic sulfide, in equal proportion, with spectroscopic properties characteristic of a [2Fe-2S] cluster-containing protein. Importantly, the interaction between RsmA and sigma(M) is dependent on the presence of the iron-sulfur cluster. We propose a model in which RsmA regulates the activity of sigma(M). Loss of the cluster, in response to an as yet unidentified signal, activates sigma(M) by abolishing its interaction with the anti-sigma factor. This represents a major extension of the functional diversity of iron-sulfur cluster proteins.
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Affiliation(s)
- Alisa A Gaskell
- Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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Crack JC, Green J, Cheesman MR, Le Brun NE, Thomson AJ. Superoxide-mediated amplification of the oxygen-induced switch from [4Fe-4S] to [2Fe-2S] clusters in the transcriptional regulator FNR. Proc Natl Acad Sci U S A 2007; 104:2092-7. [PMID: 17267605 PMCID: PMC1892919 DOI: 10.1073/pnas.0609514104] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [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: 11/18/2022] Open
Abstract
In Escherichia coli, the switch between aerobic and anaerobic metabolism is controlled primarily by FNR (regulator of fumarate and nitrate reduction), the protein that regulates the transcription of >100 genes in response to oxygen. Under oxygen-limiting conditions, FNR binds a [4Fe-4S]2+ cluster, generating a transcriptionally active dimeric form. Upon exposure to oxygen the cluster converts to a [2Fe-2S]2+ form, leading to dissociation of the protein into monomers, which are incapable of binding DNA with high affinity. The mechanism of cluster conversion together with the nature of the products of conversion is of considerable current interest. Here, we demonstrate that [4Fe-4S]2+ to [2Fe-2S]2+ cluster conversion, in both native and reconstituted [4Fe-4S] FNR, proceeds via a one electron oxidation of the cluster, to give a [3Fe-4S]1+ cluster intermediate, with the release of one Fe2+ ion and a superoxide ion. The cluster intermediate subsequently rearranges spontaneously to form the [2Fe-2S]2+ cluster, with the release of a Fe3+ ion and, as previously shown, two sulfide ions. Superoxide ion undergoes dismutation to hydrogen peroxide and oxygen. This mechanism, a one electron activation of the cluster, coupled to catalytic recycling of the resulting superoxide ion back to oxygen, provides a means of amplifying the sensitivity of [4Fe-4S] FNR to its signal molecule.
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Affiliation(s)
- Jason C. Crack
- *Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, United Kingdom; and
| | - Jeffrey Green
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Myles R. Cheesman
- *Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, United Kingdom; and
| | - Nick E. Le Brun
- *Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, United Kingdom; and
- To whom correspondence may be addressed. E-mail:
or
| | - Andrew J. Thomson
- *Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, United Kingdom; and
- To whom correspondence may be addressed. E-mail:
or
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Abstract
The Escherichia coli FNR protein regulates the transcription of >100 genes in response to environmental O2, thereby coordinating the response to anoxia. Under O2-limiting conditions, FNR binds a [4Fe-4S]2+ cluster through four cysteine residues (Cys20, Cys23, Cys29, Cys122). The acquisition of the [4Fe-4S]2+ cluster converts FNR into the transcriptionally active dimeric form. Upon exposure to O2, the cluster converts to a [2Fe-2S]2+ form, generating FNR monomers that no longer bind DNA with high affinity. The mechanism of the cluster conversion reaction and the nature of the released iron and sulfur are of considerable current interest. Here, we report the application of a novel in vitro method, involving 5,5'-dithiobis-(2-nitrobenzoic acid), for determining the oxidation state of the sulfur atoms released during FNR cluster conversion following the addition of O2. Conversion of [4Fe-4S]2+ to [2Fe-2S]2+ clusters by O2 for both native and reconstituted FNR results in the release of approximately 2 sulfide ions per [4Fe-4S]2+ cluster. This demonstrates that the reaction between O2 and the [4Fe-4S]2+ cluster does not require sulfide oxidation and hence must entail iron oxidation.
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Affiliation(s)
- Jason C Crack
- Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
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Hutchings MI, Crack JC, Shearer N, Thompson BJ, Thomson AJ, Spiro S. Transcription factor FnrP from Paracoccus denitrificans contains an iron-sulfur cluster and is activated by anoxia: identification of essential cysteine residues. J Bacteriol 2002; 184:503-8. [PMID: 11751828 PMCID: PMC139558 DOI: 10.1128/jb.184.2.503-508.2002] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Paracoccus denitrificans transcription factor FnrP has been characterized using artificial FNR-dependent promoter-lacZ fusion plasmids in Escherichia coli. FnrP can activate both class I and class II FNR-dependent promoters in response to anoxia but shows a marked preference for the class II promoter, where the FNR binding site is centered at -41.5 with respect to the transcription start site. FnrP was found to be inactive in an iscS mutant in vivo, demonstrating a requirement for cysteine desulfurase activity to assemble an iron-sulfur cluster in FnrP. Accordingly, an iron-sulfur cluster could be reconstituted into the purified protein in vitro using cysteine desulfurase, ferrous ions, and cysteine. Thus, FnrP is a true orthologue of FNR from E. coli and switches on target genes in response to anoxia. Inactivation of FnrP by oxygen very likely involves the oxidative disassembly of an iron-sulfur cluster. Possible ligands for the iron-sulfur cluster were identified by substituting each of the seven cysteine residues with serine and characterizing the altered proteins in vivo. Four substituted proteins showed activities less than 5% of the wild type, and so identify the four cysteines (Cys-14, Cys-17, Cys-25, and Cys-113) that are most likely to be involved in cluster ligation. The effects of N-oxides, NO-releasing compounds and a nitrosating agent on FNR and FnrP activity were investigated in vivo using the reporter system. Both proteins are very sensitive to the inclusion of sodium nitroprusside (a source of NO(+)) in defined growth media but are only moderately sensitive to those sources of NO that were tested.
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Affiliation(s)
- Matthew I Hutchings
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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