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Lehnert N, Kim E, Dong HT, Harland JB, Hunt AP, Manickas EC, Oakley KM, Pham J, Reed GC, Alfaro VS. The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity. Chem Rev 2021; 121:14682-14905. [PMID: 34902255 DOI: 10.1021/acs.chemrev.1c00253] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.
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Affiliation(s)
- Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Eunsuk Kim
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Jill B Harland
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Andrew P Hunt
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Elizabeth C Manickas
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Kady M Oakley
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - John Pham
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Garrett C Reed
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Victor Sosa Alfaro
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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2
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Guo Y, Marletta MA. Structural Insight into H‐NOX Gas Sensing and Cognate Signaling Protein Regulation. Chembiochem 2018; 20:7-19. [DOI: 10.1002/cbic.201800478] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Yirui Guo
- California Institute for Quantitative BiosciencesUniversity of California, Berkeley Berkeley, CA 94720 USA
| | - Michael A. Marletta
- California Institute for Quantitative BiosciencesUniversity of California, Berkeley Berkeley, CA 94720 USA
- Department of Molecular and Cell BiologyUniversity of California, Berkeley Berkeley, CA 94720 USA
- Department of ChemistryUniversity of California, Berkeley Berkeley, CA 94720 USA
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3
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Regulation of nitric oxide signaling by formation of a distal receptor-ligand complex. Nat Chem Biol 2017; 13:1216-1221. [PMID: 28967923 PMCID: PMC5698159 DOI: 10.1038/nchembio.2488] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 08/28/2017] [Indexed: 12/23/2022]
Abstract
The binding of nitric oxide (NO) to the heme cofactor of heme-nitric oxide/oxygen binding (H-NOX) proteins can lead to the dissociation of the heme-ligating histidine residue and yield a five-coordinate nitrosyl complex, which is an important step for NO-dependent signaling. In the five-coordinate nitrosyl complex, NO can reside either on the distal or proximal side of the heme, which could have a profound influence over the lifetime of the in vivo signal. To investigate this central molecular question, the Shewanella oneidensis H-NOX (So H-NOX)–NO complex was biophysically characterized under limiting and excess NO. The results show that So H-NOX preferably forms a distal NO species under both limiting and excess NO. Therefore, signal strength and complex lifetime in vivo will be dictated by the dissociation rate of NO from the distal complex and the return of the histidine ligand to the heme.
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4
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Matsumura H, Chakraborty S, Reed J, Lu Y, Moënne-Loccoz P. Effect of Outer-Sphere Side Chain Substitutions on the Fate of the trans Iron-Nitrosyl Dimer in Heme/Nonheme Engineered Myoglobins (Fe(B)Mbs): Insights into the Mechanism of Denitrifying NO Reductases. Biochemistry 2016; 55:2091-9. [PMID: 27003474 DOI: 10.1021/acs.biochem.5b01109] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Denitrifying NO reductases are transmembrane protein complexes that utilize a heme/nonheme diiron center at their active sites to reduce two NO molecules to the innocuous gas N2O. Fe(B)Mb proteins, with their nonheme iron sites engineered into the heme distal pocket of sperm whale myoglobin, are attractive models for studying the molecular details of the NO reduction reaction. Spectroscopic and structural studies of Fe(B)Mb constructs have confirmed that they reproduce the metal coordination spheres observed at the active site of the cytochrome c-dependent NO reductase from Pseudomonas aeruginosa. Exposure of Fe(B)Mb to excess NO, as examined by analytical and spectroscopic techniques, results primarily in the formation of a five-coordinate heme-nitrosyl complex without N2O production. However, substitution of the outer-sphere residue Ile107 with a glutamic acid (i.e., I107E) decreases the formation rate of the five-coordinate heme-nitrosyl complex and allows for the substoichiometric production of N2O. Here, we aim to better characterize the formation of the five-coordinate heme-nitrosyl complex and to explain why the level of N2O production increases with the I107E substitution. We follow the formation of the five-coordinate heme-nitrosyl inhibitory complex through the sequential exposure of Fe(B)Mb to different NO isotopomers using rapid-freeze-quench resonance Raman spectroscopy. The data show that the complex is formed by the displacement of the proximal histidine by a new NO molecule after the weakening of the Fe(II)-His bond in the intermediate six-coordinate low-spin (6cLS) heme-nitrosyl complex. These results lead us to explore diatomic migration within the scaffold of myoglobin and whether substitutions at residue 107 can be sufficient to control access to the proximal heme cavities. Results on a new Fe(B)Mb construct with an I107F substitution (Fe(B)Mb3) show an increased rate for the formation of the five-coordinate low-spin heme-nitrosyl complex without N2O production. Taken together, our results suggest that production of N2O from the [6cLS heme {FeNO}(7)/{Fe(B)NO}(7)] trans iron-nitrosyl dimer intermediate requires a proton transfer event facilitated by an outer-sphere residue such as E107 in Fe(B)Mb2 and E280 in P. aeruginosa cNOR.
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Affiliation(s)
- Hirotoshi Matsumura
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University , Portland, Oregon 97239, United States
| | - Saumen Chakraborty
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Julian Reed
- Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.,Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Pierre Moënne-Loccoz
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University , Portland, Oregon 97239, United States
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5
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Hough MA, Andrew CR. Cytochromes c': Structure, Reactivity and Relevance to Haem-Based Gas Sensing. Adv Microb Physiol 2015; 67:1-84. [PMID: 26616515 DOI: 10.1016/bs.ampbs.2015.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cytochromes c' are a group of class IIa cytochromes with pentacoordinate haem centres and are found in photosynthetic, denitrifying and methanotrophic bacteria. Their function remains unclear, although roles in nitric oxide (NO) trafficking during denitrification or in cellular defence against nitrosoative stress have been proposed. Cytochromes c' are typically dimeric with each c-type haem-containing monomer folding as a four-α-helix bundle. Their hydrophobic and crowded distal sites impose severe restrictions on the binding of distal ligands, including diatomic gases. By contrast, NO binds to the proximal haem face in a similar manner to that of the eukaryotic NO sensor, soluble guanylate cyclase and bacterial analogues. In this review, we focus on how structural features of cytochromes c' influence haem spectroscopy and reactivity with NO, CO and O2. We also discuss the relevance of cytochrome c' to understanding the mechanisms of gas binding to haem-based sensor proteins.
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6
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Herzik MA, Jonnalagadda R, Kuriyan J, Marletta MA. Structural insights into the role of iron-histidine bond cleavage in nitric oxide-induced activation of H-NOX gas sensor proteins. Proc Natl Acad Sci U S A 2014; 111:E4156-64. [PMID: 25253889 PMCID: PMC4210026 DOI: 10.1073/pnas.1416936111] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heme-nitric oxide/oxygen (H-NOX) binding domains are a recently discovered family of heme-based gas sensor proteins that are conserved across eukaryotes and bacteria. Nitric oxide (NO) binding to the heme cofactor of H-NOX proteins has been implicated as a regulatory mechanism for processes ranging from vasodilation in mammals to communal behavior in bacteria. A key molecular event during NO-dependent activation of H-NOX proteins is rupture of the heme-histidine bond and formation of a five-coordinate nitrosyl complex. Although extensive biochemical studies have provided insight into the NO activation mechanism, precise molecular-level details have remained elusive. In the present study, high-resolution crystal structures of the H-NOX protein from Shewanella oneidensis in the unligated, intermediate six-coordinate and activated five-coordinate, NO-bound states are reported. From these structures, it is evident that several structural features in the heme pocket of the unligated protein function to maintain the heme distorted from planarity. NO-induced scission of the iron-histidine bond triggers structural rearrangements in the heme pocket that permit the heme to relax toward planarity, yielding the signaling-competent NO-bound conformation. Here, we also provide characterization of a nonheme metal coordination site occupied by zinc in an H-NOX protein.
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Affiliation(s)
- Mark A Herzik
- Departments of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720; Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037
| | - Rohan Jonnalagadda
- Departments of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
| | - John Kuriyan
- Departments of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720; Chemistry, University of California, Berkeley, CA 94720; Howard Hughes Medical Institute, University of California, Berkeley, CA 94720; and Division of Physical Biosciences, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Michael A Marletta
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037;
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7
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Russell HJ, Hardman SJO, Heyes DJ, Hough MA, Greetham GM, Towrie M, Hay S, Scrutton NS. Modulation of ligand-heme reactivity by binding pocket residues demonstrated in cytochrome c' over the femtosecond-second temporal range. FEBS J 2013; 280:6070-82. [PMID: 24034856 PMCID: PMC4163637 DOI: 10.1111/febs.12526] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/05/2013] [Accepted: 09/10/2013] [Indexed: 12/27/2022]
Abstract
The ability of hemoproteins to discriminate between diatomic molecules, and the subsequent affinity for their chosen ligand, is fundamental to the existence of life. These processes are often controlled by precise structural arrangements in proteins, with heme pocket residues driving reactivity and specificity. One such protein is cytochrome c', which has the ability to bind nitric oxide (NO) and carbon monoxide (CO) on opposite faces of the heme, a property that is shared with soluble guanylate cycle. Like soluble guanylate cyclase, cytochrome c' also excludes O2 completely from the binding pocket. Previous studies have shown that the NO binding mechanism is regulated by a proximal arginine residue (R124) and a distal leucine residue (L16). Here, we have investigated the roles of these residues in maintaining the affinity for NO in the heme binding environment by using various time‐resolved spectroscopy techniques that span the entire femtosecond–second temporal range in the UV‐vis spectrum, and the femtosecond–nanosecond range by IR spectroscopy. Our findings indicate that the tightly regulated NO rebinding events following excitation in wild‐type cytochrome c' are affected in the R124A variant. In the R124A variant, vibrational and electronic changes extend continuously across all time scales (from fs–s), in contrast to wild‐type cytochrome c' and the L16A variant. Based on these findings, we propose a NO (re)binding mechanism for the R124A variant of cytochrome c' that is distinct from that in wild‐type cytochrome c'. In the wider context, these findings emphasize the importance of heme pocket architecture in maintaining the reactivity of hemoproteins towards their chosen ligand, and demonstrate the power of spectroscopic probes spanning a wide temporal range.
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Affiliation(s)
- Henry J Russell
- Faculty of Life Sciences, Manchester Institute of Biotechnology and Photon Science Institute, The University of Manchester, UK
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8
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Ascenzi P, Leboffe L, Polticelli F. Reactivity of the human hemoglobin “Dark side”. IUBMB Life 2013; 65:121-6. [DOI: 10.1002/iub.1121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 11/26/2012] [Indexed: 12/19/2022]
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9
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Franke A, van Eldik R. Factors That Determine the Mechanism of NO Activation by Metal Complexes of Biological and Environmental Relevance. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201201111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Garton EM, Pixton DA, Petersen CA, Eady RR, Hasnain SS, Andrew CR. A distal pocket Leu residue inhibits the binding of O2 and NO at the distal heme site of cytochrome c'. J Am Chem Soc 2012; 134:1461-3. [PMID: 22239663 DOI: 10.1021/ja209770p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytochromes c' are pentacoordinate heme proteins with sterically hindered distal sites that bind NO and CO but do not form stable complexes with O(2). Removal of distal pocket steric hindrance via a Leu→Ala mutation yields favorable O(2) binding (K(d) ~49 nM) without apparent H-bond stabilization of the Fe-O(2) moiety, as well as an extremely high distal heme-NO affinity (K(d) ~70 fM). The native Leu residue inhibits distal coordination of diatomic ligands by decreasing k(on) as well as increasing k(off). The connection between distal steric constraints, k(off) values, and distal to proximal heme-NO conversion is discussed.
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Affiliation(s)
- Elizabeth M Garton
- Department of Chemistry and Biochemistry, Eastern Oregon University, La Grande, Oregon 97850, USA
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11
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Cytochromes: Reactivity of the “dark side” of the heme. Biophys Chem 2010; 152:21-7. [DOI: 10.1016/j.bpc.2010.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 09/27/2010] [Accepted: 09/27/2010] [Indexed: 01/16/2023]
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12
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Lee B, Usov OM, Grigoryants VM, Myers WK, Shapleigh JP, Scholes CP. The role of arginine-127 at the proximal NO-binding site in determining the electronic structure and function of 5-coordinate NO-heme in cytochrome c' of Rhodobacter sphaeroides. Biochemistry 2009; 48:8985-93. [PMID: 19685879 DOI: 10.1021/bi900833f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytochrome c' is a heme protein from a denitrifying variant of Rhodobacter sphaeroides which may serve to store and transport metabolic NO while protecting against NO toxicity. Its heme site bears resemblance through its 5-coordinate NO-binding capability to the regulatory site in soluble guanylate cyclase. A conserved arginine (Arg-127) abuts the 5-coordinate NO-heme binding site, and the alanine mutant R127A provided insight into the role of the Arg-127 in establishing the electronic structure of the heme-NO complex and in modifying the heme-centered redox potential and NO-binding affinity. By comparison to R127A, the wild-type Arg-127 was determined to increase the heme redox potential, diminish the NO-binding affinity, perturb and diminish the 14NO hyperfine coupling determined by ENDOR (electron nuclear double resonance), and increase the maximal electronic g-value. The larger isotropic NO hyperfine and the smaller maximal g-value of the R127A mutant together predicted that the Fe-N-O bond angle in the mutant is larger than that of the Arg-127-containing wild-type protein. Deuterium ENDOR provided evidence for exchangeable H/D consistent with hydrogen bonding of Arg-127, but not Ala-127, to the O of the NO. Proton ENDOR features previously assigned to Phe-14 on the distal side of the heme were unperturbed by the proximal side R127A mutation, implying the localized nature of that mutational perturbation at the proximal, NO-binding side of the heme. From this work two functions of positively charged Arg-127 emerged: the first was to maintain the KD of the cytochrome c' in the 1 microM range, and the second was to provide a redox potential that enhances the stability of the ferrous heme.
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Affiliation(s)
- Byunghoon Lee
- Department of Chemistry, Center for Biochemistry and Biophysics, University at Albany, State University of New York, Albany, New York 12222, USA
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13
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Lu X, Hua Z, Du G, Ma X, Cao J, Yang Z, Chen J. Scavenging of free radicals in gas-phase mainstream cigarette smoke by immobilized catalase at filter level. Free Radic Res 2009; 42:244-52. [DOI: 10.1080/10715760801911631] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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14
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Pixton DA, Petersen CA, Franke A, van Eldik R, Garton EM, Andrew CR. Activation Parameters for Heme−NO Binding in Alcaligenes xylosoxidans Cytochrome c′: The Putative Dinitrosyl Intermediate Forms via a Dissociative Mechanism. J Am Chem Soc 2009; 131:4846-53. [PMID: 19334778 DOI: 10.1021/ja809587q] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- David A. Pixton
- Department of Chemistry and Biochemistry, Eastern Oregon University, One University Boulevard, La Grande, Oregon 97850-2899, and Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Christine A. Petersen
- Department of Chemistry and Biochemistry, Eastern Oregon University, One University Boulevard, La Grande, Oregon 97850-2899, and Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Alicja Franke
- Department of Chemistry and Biochemistry, Eastern Oregon University, One University Boulevard, La Grande, Oregon 97850-2899, and Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Rudi van Eldik
- Department of Chemistry and Biochemistry, Eastern Oregon University, One University Boulevard, La Grande, Oregon 97850-2899, and Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Elizabeth M. Garton
- Department of Chemistry and Biochemistry, Eastern Oregon University, One University Boulevard, La Grande, Oregon 97850-2899, and Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Colin R. Andrew
- Department of Chemistry and Biochemistry, Eastern Oregon University, One University Boulevard, La Grande, Oregon 97850-2899, and Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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15
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Van Doorslaer S, Desmet F. The power of using continuous-wave and pulsed electron paramagnetic resonance methods for the structure analysis of ferric forms and nitric oxide-ligated ferrous forms of globins. Methods Enzymol 2008; 437:287-310. [PMID: 18433634 DOI: 10.1016/s0076-6879(07)37015-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
Abstract
For several decades now, electron paramagnetic resonance (EPR) has been a valuable spectroscopic tool for the characterization of globin proteins. In the early years, the majority of EPR studies were performed using standard continuous-wave EPR techniques at conventional microwave frequencies. In the last years, the field of EPR has known tremendous technological developments, including the introduction of advanced pulsed EPR and high-frequency EPR techniques. After a short overview of the basics of EPR and recent advances in the field, we will illustrate how these different EPR methods can provide information about the dynamics and geometric and electronic structures of heme proteins. Although the main focus of this chapter lies on the EPR analysis of nitric oxide-ligated ferrous heme proteins and ferric heme systems, we also briefly outline the possibility of site-directed spin labeling of heme proteins. The last section highlights the future potential and challenges in using this magnetic resonance technique in globin research.
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Affiliation(s)
- Sabine Van Doorslaer
- University of Antwerp, Department of Physics, SIBAC Laboratory, Antwerp, Belgium
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16
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Cole LJ, Huston WM, Moir JWB. Delivery of nitric oxide for analysis of the function of cytochrome c'. Methods Enzymol 2008; 436:21-33. [PMID: 18237625 DOI: 10.1016/s0076-6879(08)36002-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
On delivery of nitric oxide (NO) to protein samples (e.g., cytochrome c'), for spectroscopic experiments it is important to avoid exposure to oxygen and to remove contaminants from the NO gas. We describe a number of techniques for steady-state UV/Vis spectrophotometry and pre-steady-state stopped-flow spectrophotometry analysis of cytochrome c'.
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Affiliation(s)
- Lindsay J Cole
- Department of Biology, University of York, Heslington, York, United Kingdom
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17
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Pearson AR, Elmore BO, Yang C, Ferrara JD, Hooper AB, Wilmot CM. The crystal structure of cytochrome P460 of Nitrosomonas europaea reveals a novel cytochrome fold and heme-protein cross-link. Biochemistry 2007; 46:8340-9. [PMID: 17583915 PMCID: PMC2527454 DOI: 10.1021/bi700086r] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have determined the 1.8 A X-ray crystal structure of a monoheme c-type cytochrome, cytochrome P460, from Nitrosomonas europea. The chromophore possesses unusual spectral properties analogous to those of the catalytic heme P460 of hydroxylamine oxidoreductase (HAO), the only known heme in biology to withdraw electrons from an iron-coordinated substrate. The analysis reveals a homodimeric structure and elucidates a new c-type cytochrome fold that is predominantly beta-sheet. In addition to the two cysteine thioether links to the porphyrin typical of c-type hemes, there is a third proteinaceous link involving a conserved lysine. The covalent bond is between the lysine side-chain nitrogen and the 13'-meso carbon of the heme, which, following cross-link formation, is sp3-hybridized, demonstrating the loss of conjugation at this position within the porphyrin. The structure has implications for the analogous tyrosine-heme meso carbon cross-link observed in HAO.
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Affiliation(s)
- Arwen R. Pearson
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
| | - Bradley O. Elmore
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
| | - Cheng Yang
- Rigaku Americas Corp. 9009 New Trails Drive, The Woodlands, TX, 77381, U. S. A
| | - Joseph D. Ferrara
- Rigaku Americas Corp. 9009 New Trails Drive, The Woodlands, TX, 77381, U. S. A
| | - Alan B. Hooper
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
| | - Carrie M. Wilmot
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
- Corresponding Author: Carrie M. Wilmot, e-mail: , tel: +1-612-624-2406, fax: +1-612-624-5121
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18
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Ma X, Sayed N, Beuve A, van den Akker F. NO and CO differentially activate soluble guanylyl cyclase via a heme pivot-bend mechanism. EMBO J 2007; 26:578-88. [PMID: 17215864 PMCID: PMC1783457 DOI: 10.1038/sj.emboj.7601521] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 12/01/2006] [Indexed: 11/08/2022] Open
Abstract
Diatomic ligand discrimination by soluble guanylyl cyclase (sGC) is paramount to cardiovascular homeostasis and neuronal signaling. Nitric oxide (NO) stimulates sGC activity 200-fold compared with only four-fold by carbon monoxide (CO). The molecular details of ligand discrimination and differential response to NO and CO are not well understood. These ligands are sensed by the heme domain of sGC, which belongs to the heme nitric oxide oxygen (H-NOX) domain family, also evolutionarily conserved in prokaryotes. Here we report crystal structures of the free, NO-bound, and CO-bound H-NOX domains of a cyanobacterial homolog. These structures and complementary mutational analysis in sGC reveal a molecular ruler mechanism that allows sGC to favor NO over CO while excluding oxygen, concomitant to signaling that exploits differential heme pivoting and heme bending. The heme thereby serves as a flexing wedge, allowing the N-terminal subdomain of H-NOX to shift concurrent with the transition of the six- to five-coordinated NO-bound state upon sGC activation. This transition can be modulated by mutations at sGC residues 74 and 145 and corresponding residues in the cyanobacterial H-NOX homolog.
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Affiliation(s)
- Xiaolei Ma
- Department of Biochemistry/RT500, Case Western Reserve University, Cleveland, OH, USA
| | - Nazish Sayed
- Department of Pharmacology and Physiology, New Jersey Medical School, UMDNJ, Newark, NJ, USA
| | - Annie Beuve
- Department of Pharmacology and Physiology, New Jersey Medical School, UMDNJ, Newark, NJ, USA
| | - Focco van den Akker
- Department of Biochemistry/RT500, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry/RT500, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA. Tel.: +1 216 368 8511; Fax: +1 216 368 3419; E-mail:
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19
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Soluble Guanylyl Cyclases in Invertebrates: Targets for NO and O(2). ADVANCES IN EXPERIMENTAL BIOLOGY 2007; 1:65-82. [PMID: 19122779 DOI: 10.1016/s1872-2423(07)01003-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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20
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Weiss R, Gold A, Terner J. Cytochromes c‘: Biological Models for the S = 3/2,5/2 Spin-State Admixture? Chem Rev 2006; 106:2550-79. [PMID: 16771459 DOI: 10.1021/cr040416l] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raymond Weiss
- Laboratoire de Chimie Supramoléculaires, Institut de Science et d'Ingénierie Supramoléculaires, Université Louis Pasteur de Strasbourg, 8 Allée Gaspard Monge, B.P.70028, F-67083 Strasbourg Cedex, France
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21
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Boon EM, Davis JH, Tran R, Karow DS, Huang SH, Pan D, Miazgowicz MM, Mathies RA, Marletta MA. Nitric oxide binding to prokaryotic homologs of the soluble guanylate cyclase beta1 H-NOX domain. J Biol Chem 2006; 281:21892-21902. [PMID: 16728401 DOI: 10.1074/jbc.m600557200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heme cofactor in soluble guanylate cyclase (sGC) is a selective receptor for NO, an important signaling molecule in eukaryotes. The sGC heme domain has been localized to the N-terminal 194 amino acids of the beta1 subunit of sGC and is a member of a family of conserved hemoproteins, called the H-NOX family (Heme-Nitric Oxide and/or OXygen-binding domain). Three new members of this family have now been cloned and characterized, two proteins from Legionella pneumophila (L1 H-NOX and L2 H-NOX) and one from Nostoc punctiforme (Np H-NOX). Like sGC, L1 H-NOX forms a 5-coordinate Fe(II)-NO complex. However, both L2 H-NOX and Np H-NOX form temperature-dependent mixtures of 5- and 6-coordinate Fe(II)-NO complexes; at low temperature, they are primarily 6-coordinate, and at high temperature, the equilibrium is shifted toward a 5-coordinate geometry. This equilibrium is fully reversible with temperature in the absence of free NO. This process is analyzed in terms of a thermally labile proximal Fe(II)-His bond and suggests that in both the 5- and 6-coordinate Fe(II)-NO complexes of L2 H-NOX and Np H-NOX, NO is bound in the distal heme pocket of the H-NOX fold. NO dissociation kinetics for L1 H-NOX and L2 H-NOX have been determined and support a model in which NO dissociates from the distal side of the heme in both 5- and 6-coordinate complexes.
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Affiliation(s)
- Elizabeth M Boon
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Joseph H Davis
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Rosalie Tran
- Department of Chemistry, University of California, Berkeley, California 94720
| | - David S Karow
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Shirley H Huang
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Duohai Pan
- Department of Chemistry, University of California, Berkeley, California 94720
| | | | - Richard A Mathies
- Department of Chemistry, University of California, Berkeley, California 94720; Division of Physical Biosciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Michael A Marletta
- Department of Chemistry, University of California, Berkeley, California 94720; Department of Molecular and Cell Biology, University of California, Berkeley, California 94720; Division of Physical Biosciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
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22
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Vermehren A, Langlais KK, Morton DB. Oxygen-sensitive guanylyl cyclases in insects and their potential roles in oxygen detection and in feeding behaviors. JOURNAL OF INSECT PHYSIOLOGY 2006; 52:340-8. [PMID: 16427074 DOI: 10.1016/j.jinsphys.2005.12.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 11/28/2005] [Accepted: 12/05/2005] [Indexed: 05/06/2023]
Abstract
Responses to hypoxia and hyperoxia depend critically on the ability of the animal to detect changes in O2 levels. However, it has only been recently that an O2-sensing system has been identified in invertebrates. Evidence is accumulating that this molecular O2 sensor is, surprisingly, a class of soluble guanylyl cyclase (sGC) known as atypical sGCs. It has long been known that the conventional sGC alpha and beta subunits form heterodimeric enzymes that are potently activated by NO, but do not bind O2. By contrast, the Drosophila melanogaster atypical sGC subunits, Gyc-88E, Gyc-89Da and Gyc-89Db, are only slightly sensitive to NO, but are potently activated under hypoxic conditions. Here we review evidence that suggests that the atypical sGCs can function as molecular O2 sensors mediating behavioral responses to hypoxia. Sequence comparisons of other predicted O2-sensitive sGCs suggest that most, if not all, insects express two heterodimeric sGCs; an NO-sensitive isoform and a separate O2-sensitive isoform. Expression data and recent experiments that block the function of cells that express the atypical sGCs and experiments that reduce the cGMP levels in these cells also suggest a role in behavioral responses to sweet tastants.
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Affiliation(s)
- Anke Vermehren
- Department of Integrative Biosciences, 611 SW Campus Drive, SD 715, Oregon Health & Science University, Portland, OR 97239, USA
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23
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Abstract
The five-coordinate NO-bound heme in cytochrome c' from an overexpressing variant of denitrifying R. sphaeroides 2.4.3 was investigated by proton, nitrogen, and deuterium Q-band ENDOR (electron nuclear double resonance). ENDOR was a direct probe of the unpaired electron density on the nitrogen of NO and, as measured across the EPR line shape, showed a hyperfine coupling range from 36 to 44 MHz for 14NO and 51 to 63 MHz for 15NO. The smallest NO coupling occurred at an electronic g-tensor axis perpendicular to the FeNO plane, and the largest hyperfine coupling occurred in the FeNO plane where the highest nitrogen valence spin density is located. The isotropic component of the NO hyperfine coupling indicated that the electron spin on the NO is not simply in a pi orbital having only 2p character but is in an orbital having 2s and 2p character in a 1:2 ratio. ENDOR frequencies from heme meso-protons, assigned with reference to porphyrin models, were determined to result from an anisotropic hyperfine tensor. This tensor indicated the orientation of the heme with respect to the FeNO plane and showed that the FeNO plane bisects the heme N-Fe-N 90 degrees angle. ENDOR provided additional structural information through dipolar couplings, as follows: (1) to the nearest proton of the Phe14 ring, approximately 3.1 A away from the heme iron, where Phe14 is positioned to occlude binding of NO as a 6th (distal) ligand; (2) to exchangeable deuterons assigned to Arg127 which may H-bond with the proximal NO ligand.
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Affiliation(s)
- Oleg M Usov
- Department of Chemistry, Center for Biochemistry and Biophysics, University at Albany, SUNY, Albany, New York 12222, USA
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24
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Andrew CR, Kemper LJ, Busche TL, Tiwari AM, Kecskes MC, Stafford JM, Croft LC, Lu S, Moënne-Loccoz P, Huston W, Moir JWB, Eady RR. Accessibility of the distal heme face, rather than Fe-His bond strength, determines the heme-nitrosyl coordination number of cytochromes c': evidence from spectroscopic studies. Biochemistry 2005; 44:8664-72. [PMID: 15952773 DOI: 10.1021/bi050428g] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The heme coordination chemistry and spectroscopic properties of Rhodobacter capsulatus cytochrome c' (RCCP) have been compared to data from Alcaligenes xylosoxidans (AXCP), with the aim of understanding the basis for their different reactivities with nitric oxide (NO). Whereas ferrous AXCP reacts with NO to form a predominantly five-coordinate heme-nitrosyl complex via a six-coordinate intermediate, RCCP forms an equilibrium mixture of six-coordinate and five-coordinate heme-nitrosyl species in approximately equal proportions. Ferrous RCCP and AXCP both exhibit high Fe-His stretching frequencies (227 and 231 cm(-)(1), respectively), suggesting that factors other than the Fe-His bond strength account for their differences in heme-nitrosyl coordination number. Resonance Raman spectra of ferrous-nitrosyl RCCP confirm the presence of both five-coordinate and six-coordinate heme-NO complexes. The six-coordinate heme-nitrosyl of RCCP exhibits a fairly typical Fe-NO stretching frequency (569 cm(-)(1)), in contrast to the relatively high value (579 cm(-)(1)) of the AXCP six-coordinate heme-nitrosyl intermediate. It is proposed that NO experiences greater steric hindrance in binding to the distal face of AXCP, as compared to RCCP, leading to a more distorted Fe-N-O geometry and an elevated Fe-NO stretching frequency. Evidence that RCCP has a more accessible distal coordination site than in AXCP stems from the fact that ferric RCCP readily forms a heme complex with exogenous imidazole, whereas AXCP does not. A model is proposed in which distal heme-face accessibility, rather than the proximal Fe-His bond strength, determines the heme-nitrosyl coordination number in cytochromes c'.
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Affiliation(s)
- Colin R Andrew
- Department of Chemistry & Biochemistry, Eastern Oregon University, La Grande, Oregon 97850-2899, USA.
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25
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Uchida T, Kitagawa T. Mechanism for transduction of the ligand-binding signal in heme-based gas sensory proteins revealed by resonance Raman spectroscopy. Acc Chem Res 2005; 38:662-70. [PMID: 16104689 DOI: 10.1021/ar030267d] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gene analysis has revealed a variety of new heme-containing gas sensory proteins in organisms ranging from bacteria to mammals. These proteins are composed of sensor, communication, and functional domains. The sensor domain contains a heme that binds effector molecules such as NO, O2, or CO. Ligand binding by the sensor domain modulates the physiological role of the protein, such as DNA binding in the case of transcriptional factors or the catalytic reaction rate in the case of enzymes. This Account summarizes resonance Raman (RR) studies, including static and time-resolved measurements, which have enabled elucidation of the mechanisms by which binding of specific target molecule by the sensor domain is transduced to alteration of the functional domain. These studies have shown that signals can be conveyed from the heme to the functional domain via three different pathways: (i) a distal pathway, (ii) a proximal pathway, and (iii) a heme peripheral pathway.
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Affiliation(s)
- Takeshi Uchida
- Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan
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26
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Choi PS, Grigoryants VM, Abruña HD, Scholes CP, Shapleigh JP. Regulation and function of cytochrome c' in Rhodobacter sphaeroides 2.4.3. J Bacteriol 2005; 187:4077-85. [PMID: 15937170 PMCID: PMC1151734 DOI: 10.1128/jb.187.12.4077-4085.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cytochrome c' (Cyt c') is a c-type cytochrome with a pentacoordinate heme iron. The gene encoding this protein in Rhodobacter sphaeroides 2.4.3, designated cycP, was isolated and sequenced. Northern blot analysis and beta-galactosidase assays demonstrated that cycP transcription increased as oxygen levels decreased and was not repressed under denitrifying conditions as observed in another Rhodobacter species. CO difference spectra performed with extracts of cells grown under different conditions revealed that Cyt c' levels were highest during photosynthetic denitrifying growth conditions. The increase in Cyt c' under this condition was higher than would be predicted from transcriptional studies. Electron paramagnetic resonance analysis of whole cells demonstrated that Cyt c' binds NO during denitrification. Mass spectrometric analysis of nitrogen oxides produced by cells and purified protein did not indicate that Cyt c' has NO reductase activity. Taken together, these results suggest a model where Cyt c' in R. sphaeroides 2.4.3 may shuttle NO to the membrane, where it can be reduced.
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Affiliation(s)
- Peter S Choi
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, NY 14853, USA
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27
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Usov OM, Choi PST, Shapleigh JP, Scholes CP. ENDOR Investigation of the Liganding Environment of Mixed-Spin Ferric Cytochrome c‘. J Am Chem Soc 2005; 127:9485-94. [PMID: 15984875 DOI: 10.1021/ja043994s] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The electronic structure of the 5-coordinate quantum-mechanically mixed-spin (sextet-quartet) heme center in cytochrome c' was investigated by electron nuclear double resonance (ENDOR), a technique not previously applied to this mixed-spin system. Cytochrome c' was obtained from overexpressing variants of Rhodobacter sphaeroides 2.4.3. ENDOR for this study was done at the g(//) = 2.00 extremum where single-crystal-like, well-resolved spectra prevail. The heme meso protons of cytochrome c' showed a contact interaction that implied spin delocalization arising from the heme (d(z)(2)) orbital enhanced by iron out-of-planarity. An exchangeable proton ENDOR feature appeared from the proximal His123 Ndelta hydrogen. This Ndelta hydrogen, which crystallographically has no hydrogen-bonding partner and thus belongs to a neutral imidazole, showed a larger hyperfine coupling than the corresponding hydrogen-bonded Ndelta proton from metmyoglobin. The unique residue Phe14 occludes binding of a sixth ligand in cytochrome c', and ENDOR from a proton of the functionally important Phe14 ring, approximately 3.3 A away from the heme iron, was detected. ENDOR of the nitrogen ligand hyperfine structure is a direct probe into the sigma-antibonding (d(z)(2)) and (d(x)(2)-d(y)(2)) orbitals whose energies alter the relative stability and admixture of sextet and quartet states and whose electronic details were thus elucidated. ENDOR frequencies showed for cytochrome c' larger hyperfine couplings to the histidine nitrogen and smaller hyperfine couplings to the heme nitrogens than for high-spin ferric hemes. Both of these findings followed from the mixed-spin ground state, which has less (d(x)(2)-d(y)(2)) character than have fully high-spin ferric heme systems.
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Affiliation(s)
- Oleg M Usov
- Department of Chemistry, Center for Biochemistry and Biophysics, University at Albany, SUNY, Albany, New York 12222, USA
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28
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Martí MA, Capece L, Crespo A, Doctorovich F, Estrin DA. Nitric Oxide Interaction with Cytochromec‘ and Its Relevance to Guanylate Cyclase. Why Does the Iron Histidine Bond Break? J Am Chem Soc 2005; 127:7721-8. [PMID: 15913362 DOI: 10.1021/ja042870c] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Soluble guanylate cyclase (sGC), the mammalian receptor for nitric oxide (NO), is a heme protein with a histidine as the proximal ligand. Formation of a five-coordinate heme-NO complex with the associated Fe-His bond cleavage is believed to trigger a conformational change that activates the enzyme and transduces the NO signal. Cytochrome c' (cyt c') is a protobacteria heme protein that has several similarities with sGC, including the ability to form a five-coordinate NO adduct and the fact that it does not bind oxygen. Recent crystallographic characterization of cyt c' from Alcaligenes xylosoxidans (AXCP) has yielded the discovery that exogenous ligands are able to bind to the Fe center from either side of the porphyrin plane. In this paper, we explore the molecular basis of the NO interaction with AXCP using hybrid quantum-classical simulation techniques. Our results suggest that Fe-His bond breaking depends not only on the iron-histidine bond strength but also on the existence of a local minimum conformation of the protein with the histidine away from the iron. We also show that AXCP is a useful paradigm for NO interaction with heme proteins, particularly regarding the activation/deactivation mechanism of sGC. The results presented here fully support a recently proposed model of sGC activation in which NO is not only the iron ligand but also catalyzes the activation step.
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Affiliation(s)
- Marcelo A Martí
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, Buenos Aires, Argentina
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29
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Chang FJ, Lemme S, Sun Q, Sunahara RK, Beuve A. Nitric oxide-dependent allosteric inhibitory role of a second nucleotide binding site in soluble guanylyl cyclase. J Biol Chem 2005; 280:11513-9. [PMID: 15649897 DOI: 10.1074/jbc.m412203200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism of desensitization of the nitric oxide (NO) receptor (alpha1.beta1 isoform of soluble guanylyl cyclase, sGC) is not known. Models of the structure of alpha1.beta1, based on the x-ray crystal structure of adenylyl cyclase (AC) suggest the existence of a nucleotide-like binding site, in addition to the putative catalytic site. We have previously reported that mutating residues that coordinate Mg(2+)GTP (substrate) binding in alpha1.beta1 into those present in AC fully reverts GC activity to AC activity. The wild-type form of alpha1.beta1 (GC-wt) and the mutant form (AC-mut, alpha1R592Q.beta1E473K,C541D) were purified, and their sensitivities to various nucleotides were assessed. In using the AC-mut as well as other mutants that coordinate purine binding, we were able to distinguish allosteric inhibitory effects of guanine nucleotides from competitively inhibitory effects on catalytic activity. Here we report that several nucleotide analogs drastically alter sGC and AC-mut activity by acting at a second nucleotide site, likely pseudosymmetric to the catalytic site. In particular, Mg(2+)GTP gamma S and Mg(2+)ATP gamma S inhibited cyclase activity through a mixed, non-competitive mechanism that was only observable under NO stimulation and not under basal conditions. The non-competitive pattern of inhibition was not present in mutants carrying the substitution beta1D477A, the pseudosymmetric equivalent to alpha1D529 (located in the substrate-binding site and involved in substrate binding and catalysis), or with the double mutations alpha1E525K,C594D, the pseudosymmetric equivalent to beta1E473K,C541D. Taken together these data suggest that occupation of the second site by nucleotides may underlie part of the mechanism of desensitization of sGC.
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Affiliation(s)
- Fu-Jung Chang
- Department of Pharmacology and Physiology, New Jersey Medical School-UMDNJ, Newark, New Jersey 07103, USA
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30
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Morton DB. Atypical soluble guanylyl cyclases in Drosophila can function as molecular oxygen sensors. J Biol Chem 2004; 279:50651-3. [PMID: 15485853 DOI: 10.1074/jbc.c400461200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Conventional soluble guanylyl cyclases are heterodimeric enzymes that synthesize cGMP and are activated by nitric oxide. Recently, a separate class of soluble guanylyl cyclases has been identified that are only slightly activated by or are insensitive to nitric oxide. These atypical guanylyl cyclases include the vertebrate beta2 subunit and examples from the invertebrates Manduca sexta, Caenorhabditis elegans, and Drosophila melanogaster. A member of this family, GCY-35 in C. elegans, was recently shown to be required for a behavioral response to low oxygen levels and may be directly regulated by oxygen (Gray, J. M., Karow, D. S., Lu, H., Chang, A. J., Chang, J. S., Ellis, R. E., Marletta, M. A., and Bargmann, C. I. (2004) Nature 430, 317-322). Drosophila contains three genes that code for atypical soluble guanylyl cyclases: Gyc-88E, Gyc-89Da, and Gyc-89Db. COS-7 cells co-transfected with Gyc-88E and Gyc-89Da or Gyc-89Db accumulate low levels of cGMP under normal atmospheric oxygen concentrations and are potently activated under anoxic conditions. The increase in activity is graded over oxygen concentrations of 0-21%, can be detected within 1 min of exposure to anoxic conditions and is blocked by the soluble guanylyl cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ). Gyc-88E and Gyc-89Db are co-expressed in a subset of sensory neurons where they would be ideally situated to act as oxygen sensors. This is the first demonstration of a soluble guanylyl cyclase that is activated in response to changing oxygen concentrations.
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Affiliation(s)
- David B Morton
- Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon 97239, USA.
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Russwurm M, Koesling D. NO activation of guanylyl cyclase. EMBO J 2004; 23:4443-50. [PMID: 15510222 PMCID: PMC526456 DOI: 10.1038/sj.emboj.7600422] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Accepted: 09/01/2004] [Indexed: 11/08/2022] Open
Abstract
Nitric oxide (NO)-sensitive guanylyl-cyclase (GC) is the most important receptor for the signaling molecule NO. Activation of the enzyme is brought about by binding of NO to the prosthetic heme group. By monitoring NO-binding and catalytic activity simultaneously, we show that NO activates GC only if the reaction products of the enzyme are present. NO-binding in the absence of the products did not activate the enzyme, but yielded a nonactivated species with the spectral characteristics of the active form. Conversion of the nonactivated into the activated conformation of the enzyme required the simultaneous presence of NO and the reaction products. Furthermore, the products magnesium/cGMP/pyrophosphate promoted the release of the histidine-iron bond during NO-binding, indicating reciprocal communication of the catalytic and ligand-binding domains. Based on these observations, we present a model that proposes two NO-bound states of the enzyme: an active state formed in the presence of the products and a nonactivated state. The model not only covers the data reported here but also consolidates results from previous studies on NO-binding and dissociation/deactivation of GC.
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Affiliation(s)
- Michael Russwurm
- Institute for Pharmacology und Toxicology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
| | - Doris Koesling
- Institute for Pharmacology und Toxicology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
- Institute for Pharmacology and Toxicology, Medical Faculty MA N1/39, Ruhr-University Bochum, 44780 Bochum, Germany. Tel.: +49 234 322 6827; Fax: +49 234 321 4521; E-mail:
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Koesling D, Russwurm M, Mergia E, Mullershausen F, Friebe A. Nitric oxide-sensitive guanylyl cyclase: structure and regulation. Neurochem Int 2004; 45:813-9. [PMID: 15312975 DOI: 10.1016/j.neuint.2004.03.011] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
By the formation of the second messenger cGMP, NO-sensitive guanylyl cyclase (GC) plays a key role within the NO/cGMP signaling cascade which participates in vascular regulation and neurotransmission. The enzyme contains a prosthetic heme group that acts as the acceptor site for NO. High affinity binding of NO to the heme moiety leads to an up to 200-fold activation of the enzyme. Unexpectedly, NO dissociates with a half-life of a few seconds which appears fast enough to account for the deactivation of the enzyme in biological systems. YC-1 and its analogs act as NO sensitizers and led to the discovery of a novel pharmacologically and conceivably physiologically relevant regulatory principle of the enzyme. The two isoforms of the heterodimeric enzyme (alpha1beta1, alpha2beta1) are known that are functionally indistinguishable. The alpha2beta1-isoform mainly occurs in brain whereas the alpha1beta1-enzyme shows a broader distribution and represents the predominantly expressed form of NO-sensitive GC. Until recently, the enzyme has been thought to occur in the cytosol. However, latest evidence suggests that the alpha2-subunit mediates the membrane association of the alpha2beta1-isoform via interaction with a PDZ domain of the post-synaptic scaffold protein PSD-95. Binding to PSD-95 locates this isoform in close proximity to the NO-generating synthases thereby enabling the NO sensor to respond to locally elevated NO concentrations. In sum, the two known isoforms may stand for the neuronal and vascular form of NO-sensitive GC reflecting a possible association to the neuronal and endothelial NO-synthase, respectively.
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Affiliation(s)
- Doris Koesling
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät MA N1, Ruhr-Universität Bochum, 44780 Bochum, Germany.
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Igarashi J, Sato A, Kitagawa T, Yoshimura T, Yamauchi S, Sagami I, Shimizu T. Activation of heme-regulated eukaryotic initiation factor 2alpha kinase by nitric oxide is induced by the formation of a five-coordinate NO-heme complex: optical absorption, electron spin resonance, and resonance raman spectral studies. J Biol Chem 2004; 279:15752-62. [PMID: 14752110 DOI: 10.1074/jbc.m310273200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Heme-regulated eukaryotic initiation factor 2alpha kinase (HRI) regulates the synthesis of hemoglobin in reticulocytes in response to heme availability. HRI contains a tightly bound heme at the N-terminal domain. Earlier reports show that nitric oxide (NO) regulates HRI catalysis. However, the mechanism of this process remains unclear. In the present study, we utilize in vitro kinase assays, optical absorption, electron spin resonance (ESR), and resonance Raman spectra of purified full-length HRI for the first time to elucidate the regulation mechanism of NO. HRI was activated via heme upon NO binding, and the Fe(II)-HRI(NO) complex displayed 5-fold greater eukaryotic initiation factor 2alpha kinase activity than the Fe(III)-HRI complex. The Fe(III)-HRI complex exhibited a Soret peak at 418 nm and a rhombic ESR signal with g values of 2.49, 2.28, and 1.87, suggesting coordination with Cys as an axial ligand. Interestingly, optical absorption, ESR, and resonance Raman spectra of the Fe(II)-NO complex were characteristic of five-coordinate NO-heme. Spectral findings on the coordination structure of full-length HRI were distinct from those obtained for the isolated N-terminal heme-binding domain. Specifically, six-coordinate NO-Fe(II)-His was observed but not Cys-Fe(III) coordination. It is suggested that significant conformational change(s) in the protein induced by NO binding to the heme lead to HRI activation. We discuss the role of NO and heme in catalysis by HRI, focusing on heme-based sensor proteins.
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Affiliation(s)
- Jotaro Igarashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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