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Lundahl MN, Greiner MB, Piquette MC, Gannon PM, Kaminsky W, Kovacs JA. Exploring the influence of H-bonding and ligand constraints on thiolate ligated non-heme iron mediated dioxygen activation. Chem Sci 2024; 15:12710-12720. [PMID: 39148773 PMCID: PMC11325341 DOI: 10.1039/d4sc02787f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 07/05/2024] [Indexed: 08/17/2024] Open
Abstract
Converting triplet dioxygen into a powerful oxidant is fundamentally important to life. The study reported herein quantitatively examines the formation of a well-characterized, reactive, O2-derived thiolate ligated FeIII-superoxo using low-temperature stopped-flow kinetics. Comparison of the kinetic barriers to the formation of this species via two routes, involving either the addition of (a) O2 to [FeII(S2 Me2N3(Pr,Pr))] (1) or (b) superoxide to [FeIII(S2 Me2N3(Pr,Pr))]+ (3) is shown to provide insight into the mechanism of O2 activation. Route (b) was shown to be significantly slower, and the kinetic barrier 14.9 kJ mol-1 higher than route (a), implying that dioxygen activation involves inner-sphere, as opposed to outer sphere, electron transfer from Fe(ii). H-bond donors and ligand constraints are shown to dramatically influence O2 binding kinetics and reversibility. Dioxygen binds irreversibly to [FeII(S2 Me2N3(Pr,Pr))] (1) in tetrahydrofuran, but reversibly in methanol. Hydrogen bonding decreases the ability of the thiolate sulfur to stabilize the transition state and the FeIII-superoxo, as shown by the 10 kJ mol-1 increase in the kinetic barrier to O2 binding in methanol vs. tetrahydrofuran. Dioxygen release from [FeIII(S2 Me2N3(Pr,Pr))O2] (2) is shown to be 24 kJ mol-1 higher relative to previously reported [FeIII(SMe2N4(tren))(O2)]+ (5), the latter of which contains a more flexible ligand. These kinetic results afford an experimentally determined reaction coordinate that illustrates the influence of H-bonding and ligand constraints on the kinetic barrier to dioxygen activation an essential step in biosynthetic pathways critical to life.
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Affiliation(s)
- Maike N Lundahl
- Department of Chemistry, University of Washington Campus Box 351700 Seattle WA 98195 USA
| | - Maria B Greiner
- Department of Chemistry, University of Washington Campus Box 351700 Seattle WA 98195 USA
| | - Marc C Piquette
- Department of Chemistry, Tufts University 62 Talbot Avenue Medford Massachusetts 02155 USA
| | - Paige M Gannon
- Department of Chemistry, University of Washington Campus Box 351700 Seattle WA 98195 USA
| | - Werner Kaminsky
- Department of Chemistry, University of Washington Campus Box 351700 Seattle WA 98195 USA
| | - Julie A Kovacs
- Department of Chemistry, University of Washington Campus Box 351700 Seattle WA 98195 USA
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2
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π-Helix controls activity of oxygen-sensing diguanylate cyclases. Biosci Rep 2021; 40:222070. [PMID: 32039439 PMCID: PMC7033309 DOI: 10.1042/bsr20193602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 11/18/2022] Open
Abstract
The ability of organisms to sense and adapt to oxygen levels in their environment leads to changes in cellular phenotypes, including biofilm formation and virulence. Globin coupled sensors (GCSs) are a family of heme proteins that regulate diverse functions in response to O2 levels, including modulating synthesis of cyclic dimeric guanosine monophosphate (c-di-GMP), a bacterial second messenger that regulates biofilm formation. While GCS proteins have been demonstrated to regulate O2-dependent pathways, the mechanism by which the O2 binding event is transmitted from the globin domain to the cyclase domain is unknown. Using chemical cross-linking and subsequent liquid chromatography-tandem mass spectrometry, diguanylate cyclase (DGC)-containing GCS proteins from Bordetella pertussis (BpeGReg) and Pectobacterium carotovorum (PccGCS) have been demonstrated to form direct interactions between the globin domain and a middle domain π-helix. Additionally, mutation of the π-helix caused major changes in oligomerization and loss of DGC activity. Furthermore, results from assays with isolated globin and DGC domains found that DGC activity is affected by the cognate globin domain, indicating unique interactions between output domain and cognate globin sensor. Based on these studies a compact GCS structure, which depends on the middle domain π-helix for orienting the three domains, is needed for DGC activity and allows for direct sensor domain interactions with both middle and output domains to transmit the O2 binding signal. The insights from the present study improve our understanding of DGC regulation and provide insight into GCS signaling that may lead to the ability to rationally control O2-dependent GCS activity.
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3
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Ultrafast dynamics of heme distortion in the O 2-sensor of a thermophilic anaerobe bacterium. Commun Chem 2021; 4:31. [PMID: 36697566 PMCID: PMC9814294 DOI: 10.1038/s42004-021-00471-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 02/05/2021] [Indexed: 01/28/2023] Open
Abstract
Heme-Nitric oxide and Oxygen binding protein domains (H-NOX) are found in signaling pathways of both prokaryotes and eukaryotes and share sequence homology with soluble guanylate cyclase, the mammalian NO receptor. In bacteria, H-NOX is associated with kinase or methyl accepting chemotaxis domains. In the O2-sensor of the strict anaerobe Caldanaerobacter tengcongensis (Ct H-NOX) the heme appears highly distorted after O2 binding, but the role of heme distortion in allosteric transitions was not yet evidenced. Here, we measure the dynamics of the heme distortion triggered by the dissociation of diatomics from Ct H-NOX using transient electronic absorption spectroscopy in the picosecond to millisecond time range. We obtained a spectroscopic signature of the heme flattening upon O2 dissociation. The heme distortion is immediately (<1 ps) released after O2 dissociation to produce a relaxed state. This heme conformational change occurs with different proportions depending on diatomics as follows: CO < NO < O2. Our time-resolved data demonstrate that the primary structural event of allostery is the heme distortion in the Ct H-NOX sensor, contrastingly with hemoglobin and the human NO receptor, in which the primary structural events are respectively the motion of the proximal histidine and the rupture of the iron-histidine bond.
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4
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A new paradigm for gaseous ligand selectivity of hemoproteins highlighted by soluble guanylate cyclase. J Inorg Biochem 2020; 214:111267. [PMID: 33099233 DOI: 10.1016/j.jinorgbio.2020.111267] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/23/2020] [Accepted: 09/27/2020] [Indexed: 02/06/2023]
Abstract
Nitric oxide (NO), carbon monoxide (CO), and oxygen (O2) are important physiological messengers whose concentrations vary in a remarkable range, [NO] typically from nM to several μM while [O2] reaching to hundreds of μM. One of the machineries evolved in living organisms for gas sensing is sensor hemoproteins whose conformational change upon gas binding triggers downstream response cascades. The recently proposed "sliding scale rule" hypothesis provides a general interpretation for gaseous ligand selectivity of hemoproteins, identifying five factors that govern gaseous ligand selectivity. Hemoproteins have intrinsic selectivity for the three gases due to a neutral proximal histidine ligand while proximal strain of heme and distal steric hindrance indiscriminately adjust the affinity of these three gases for heme. On the other hand, multiple-step NO binding and distal hydrogen bond donor(s) specifically enhance affinity for NO and O2, respectively. The "sliding scale rule" hypothesis provides clear interpretation for dramatic selectivity for NO over O2 in soluble guanylate cyclase (sGC) which is an important example of sensor hemoproteins and plays vital roles in a wide range of physiological functions. The "sliding scale rule" hypothesis has so far been validated by all experimental data and it may guide future designs for heme-based gas sensors.
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5
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Sanyal R, Bhagi-Damodaran A. An enzymatic method for precise oxygen affinity measurements over nanomolar-to-millimolar concentration regime. J Biol Inorg Chem 2020; 25:181-186. [PMID: 31897725 DOI: 10.1007/s00775-019-01750-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/03/2019] [Indexed: 10/25/2022]
Abstract
Oxygen affinity is an important property of metalloproteins that helps elucidate their reactivity profile and mechanism. Heretofore, oxygen affinity values were determined either using flash photolysis and polarography techniques that require expensive instrumentation, or using oxygen titration methods which are erroneous at low nanomolar and at high millimolar oxygen concentrations. Here, we describe an inexpensive, easy-to-setup, and a one-pot method for oxygen affinity measurements that uses the enzyme chlorite dismutase (Cld) as a precise in situ oxygen source. Using this method, we measure thermodynamic and kinetic oxygen affinities (Kd and KM) of different classes of heme and non-heme metalloproteins involved in oxygen transport, sensing, and catalysis. The method enables oxygen affinity measurements over a wide concentration range from 10 nM to 5 mM which is unattainable by simply diluting oxygen-saturated buffers. In turn, we were able to precisely measure oxygen affinities of a model set of eight different metalloproteins with affinities ranging from 48 ± 3 nM to 1.18 ± 0.03 mM. Overall, the Cld method is easy and inexpensive to set up, requires significantly lower quantities of protein, enables precise oxygen affinity measurements, and is applicable for proteins exhibiting nanomolar-to-millimolar affinity values.
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Affiliation(s)
- Ria Sanyal
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
| | - Ambika Bhagi-Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA.
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6
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Makrynitsa GI, Zompra AA, Argyriou AI, Spyroulias GA, Topouzis S. Therapeutic Targeting of the Soluble Guanylate Cyclase. Curr Med Chem 2019; 26:2730-2747. [PMID: 30621555 DOI: 10.2174/0929867326666190108095851] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/13/2018] [Accepted: 04/03/2018] [Indexed: 11/22/2022]
Abstract
The soluble guanylate cyclase (sGC) is the physiological sensor for nitric oxide and alterations of its function are actively implicated in a wide variety of pathophysiological conditions. Intense research efforts over the past 20 years have provided significant information on its regulation, culminating in the rational development of approved drugs or investigational lead molecules, which target and interact with sGC through novel mechanisms. However, there are numerous questions that remain unanswered. Ongoing investigations, with the critical aid of structural chemistry studies, try to further elucidate the enzyme's structural characteristics that define the association of "stimulators" or "activators" of sGC in the presence or absence of the heme moiety, respectively, as well as the precise conformational attributes that will allow the design of more innovative and effective drugs. This review relates the progress achieved, particularly in the past 10 years, in understanding the function of this enzyme, and focusses on a) the rationale and results of its therapeutic targeting in disease situations, depending on the state of enzyme (oxidized or not, heme-carrying or not) and b) the most recent structural studies, which should permit improved design of future therapeutic molecules that aim to directly upregulate the activity of sGC.
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Affiliation(s)
| | - Aikaterini A Zompra
- Department of Pharmacy, School of Health Sciences, University of Patras, Rio, 26505, Greece
| | - Aikaterini I Argyriou
- Department of Pharmacy, School of Health Sciences, University of Patras, Rio, 26505, Greece
| | - Georgios A Spyroulias
- Department of Pharmacy, School of Health Sciences, University of Patras, Rio, 26505, Greece
| | - Stavros Topouzis
- Department of Pharmacy, School of Health Sciences, University of Patras, Rio, 26505, Greece
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7
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Abstract
SIGNIFICANCE The molecule nitric oxide (NO) has been shown to regulate behaviors in bacteria, including biofilm formation. NO detection and signaling in bacteria is typically mediated by hemoproteins such as the bis-(3',5')-cyclic dimeric adenosine monophosphate-specific phosphodiesterase YybT, the transcriptional regulator dissimilative nitrate respiration regulator, or heme-NO/oxygen binding (H-NOX) domains. H-NOX domains are well-characterized primary NO sensors that are capable of detecting nanomolar NO and influencing downstream signal transduction in many bacterial species. However, many bacteria, including the human pathogen Pseudomonas aeruginosa, respond to nanomolar concentrations of NO but do not contain an annotated H-NOX domain, indicating the existence of an additional nanomolar NO-sensing protein (NosP). Recent Advances: A newly discovered bacterial hemoprotein called NosP may also act as a primary NO sensor in bacteria, in addition to, or in place of, H-NOX. NosP was first described as a regulator of a histidine kinase signal transduction pathway that is involved in biofilm formation in P. aeruginosa. CRITICAL ISSUES The molecular details of NO signaling in bacteria are still poorly understood. There are still many bacteria that are NO responsive but do encode either H-NOX or NosP domains in their genomes. Even among bacteria that encode H-NOX or NosP, many questions remain. FUTURE DIRECTIONS The molecular mechanisms of NO regulation in many bacteria remain to be established. Future studies are required to gain knowledge about the mechanism of NosP signaling. Advancements on structural and molecular understanding of heme-based sensors in bacteria could lead to strategies to alleviate or control bacterial biofilm formation or persistent biofilm-related infections.
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Affiliation(s)
| | - Lisa-Marie Nisbett
- 2 Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York
| | - Bezalel Bacon
- 2 Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York
| | - Elizabeth Boon
- 1 Department of Chemistry, Stony Brook University , Stony Brook, New York.,2 Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York.,3 Institute of Chemical Biology and Drug Design, Stony Brook University , Stony Brook, New York
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8
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Kearney C, Olenginski LT, Hirn TD, Fowler GD, Tariq D, Brewer SH, Phillips-Piro CM. Exploring local solvation environments of a heme protein using the spectroscopic reporter 4-cyano-l-phenylalanine. RSC Adv 2018; 8:13503-13512. [PMID: 29780583 PMCID: PMC5944249 DOI: 10.1039/c8ra02000k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 03/20/2018] [Indexed: 11/21/2022] Open
Abstract
The vibrational reporter unnatural amino acid (UAA) 4-cyano-l-phenylalanine (pCNF) was genetically incorporated individually at three sites (5, 36, and 78) in the heme protein Caldanaerobacter subterraneus H-NOX to probe local hydration environments. The UAA pCNF was incorporated site-specifically using an engineered, orthogonal tRNA synthetase in E. coli. The ability of all of the pCNF-containing H-NOX proteins to form the ferrous CO, NO, or O2 ligated and unligated states was confirmed with UV-Vis spectroscopy. The solvation state at each site of the three sites of pCNF incorporation was assessed using temperature-dependent infrared spectroscopy. Specifically, the frequency-temperature line slope (FTLS) method was utilized to show that the nitrile group at site 36 was fully solvated and the nitrile group at site 78 was de-solvated (buried) in the heme pocket. The nitrile group at site 5 was found to be partially solvated suggesting that the nitrile group was involved in moderate strength hydrogen bonds. These results were confirmed by the determination of the X-ray crystal structure of the H-NOX protein construct containing pCNF at site 5.
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Affiliation(s)
- Caroline Kearney
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA. ;
| | - Lukasz T Olenginski
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA. ;
| | - Trexler D Hirn
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA. ;
| | - Gwendolyn D Fowler
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA. ;
| | - Daniyal Tariq
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA. ;
| | - Scott H Brewer
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA. ;
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9
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Abstract
Low concentrations of nitric oxide (NO) modulate varied behaviours in bacteria including biofilm dispersal and quorum sensing-dependent light production. H-NOX (haem-nitric oxide/oxygen binding) is a haem-bound protein domain that has been shown to be involved in mediating these bacterial responses to NO in several organisms. However, many bacteria that respond to nanomolar concentrations of NO do not contain an annotated H-NOX domain. Nitric oxide sensing protein (NosP), a newly discovered bacterial NO-sensing haemoprotein, may fill this role. The focus of this review is to discuss structure, ligand binding, and activation of H-NOX proteins, as well as to discuss the early evidence for NO sensing and regulation by NosP domains. Further, these findings are connected to the regulation of bacterial biofilm phenotypes and symbiotic relationships.
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Affiliation(s)
- Bezalel Bacon
- Stony Brook University, Stony Brook, NY, United States
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10
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Rivera S, Burns JL, Vansuch GE, Chica B, Weinert EE. Globin domain interactions control heme pocket conformation and oligomerization of globin coupled sensors. J Inorg Biochem 2016; 164:70-76. [PMID: 27614715 DOI: 10.1016/j.jinorgbio.2016.08.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 08/24/2016] [Accepted: 08/26/2016] [Indexed: 12/24/2022]
Abstract
Globin coupled sensors (GCS) are O2-sensing proteins used by bacteria to monitor the surrounding gaseous environment. To investigate the biphasic O2 dissociation kinetics observed for full-length GCS proteins, isolated globin domains from Pectobacterium carotovorum ssp. carotovorum (PccGlobin), and Bordetella pertussis (BpeGlobin), have been characterized. PccGlobin is found to be dimeric, while BpeGlobin is monomeric, indicating key differences in the globin domain dimer interface. Through characterization of wild type globin domains and globin variants with mutations at the dimer interface and within the distal pocket, dimerization of the globin domain is demonstrated to correlate with biphasic dissociation kinetics. Furthermore, a distal pocket tyrosine is identified as the primary hydrogen bond donor, while a secondary hydrogen bond donor within the distal heme pocket is involved in conformation(s) that lead to the second O2 dissociation rate. These findings highlight the role of the globin dimer interface in controlling properties of both the heme pocket and full-length GCS proteins.
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Affiliation(s)
- Shannon Rivera
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA
| | - Justin L Burns
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA
| | - Gregory E Vansuch
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA
| | - Bryant Chica
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA
| | - Emily E Weinert
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA.
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11
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Hespen CW, Bruegger JJ, Phillips-Piro CM, Marletta MA. Structural and Functional Evidence Indicates Selective Oxygen Signaling in Caldanaerobacter subterraneus H-NOX. ACS Chem Biol 2016; 11:2337-46. [PMID: 27328180 DOI: 10.1021/acschembio.6b00431] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Acute and specific sensing of diatomic gas molecules is an essential facet of biological signaling. Heme nitric oxide/oxygen binding (H-NOX) proteins are a family of gas sensors found in diverse classes of bacteria and eukaryotes. The most commonly characterized bacterial H-NOX domains are from facultative anaerobes and are activated through a conformational change caused by formation of a 5-coordinate Fe(II)-NO complex. Members of this H-NOX subfamily do not bind O2 and therefore can selectively ligate NO even under aerobic conditions. In contrast, H-NOX domains encoded by obligate anaerobes do form stable 6-coordinate Fe(II)-O2 complexes by utilizing a conserved H-bonding network in the ligand-binding pocket. The biological function of O2-binding H-NOX domains has not been characterized. In this work, the crystal structures of an O2-binding H-NOX domain from the thermophilic obligate anaerobe Caldanaerobacter subterraneus (Cs H-NOX) in the Fe(II)-NO, Fe(II)-CO, and Fe(II)-unliganded states are reported. The Fe(II)-unliganded structure displays a conformational shift distinct from the NO-, CO-, and previously reported O2-coordinated structures. In orthogonal signaling assays using Cs H-NOX and the H-NOX signaling effector histidine kinase from Vibrio cholerae (Vc HnoK), Cs H-NOX regulates Vc HnoK in an O2-dependent manner and requires the H-bonding network to distinguish O2 from other ligands. The crystal structures of Fe(II) unliganded and NO- and CO-bound Cs H-NOX combined with functional assays herein provide the first evidence that H-NOX proteins from obligate anaerobes can serve as O2 sensors.
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Affiliation(s)
- Charles W. Hespen
- Department
of Molecular and Cell Biology, University of California—Berkeley, 356 Stanley Hall, Berkeley, California 94720-3220, United States
| | - Joel J. Bruegger
- QB3
Institute, University of California—Berkeley, 356 Stanley Hall, Berkeley, California, 94720-3220, United States
| | - Christine M. Phillips-Piro
- Department of Chemistry, HAC 416 Franklin & Marshall College, Lancaster, Pennsylvania 17604-3003, United States
| | - Michael A. Marletta
- Department
of Molecular and Cell Biology, University of California—Berkeley, 356 Stanley Hall, Berkeley, California 94720-3220, United States
- Department
of Chemistry Department of Molecular and Cell Biology QB3 Institute, University of California—Berkeley, 374B Stanley Hall, Berkeley, California 94720-3220, United States
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12
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Wu G, Liu W, Berka V, Tsai AL. H-NOX from Clostridium botulinum, like H-NOX from Thermoanaerobacter tengcongensis, Binds Oxygen but with a Less Stable Oxyferrous Heme Intermediate. Biochemistry 2015; 54:7098-109. [PMID: 26574914 DOI: 10.1021/acs.biochem.5b00994] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Heme nitric oxide/oxygen binding protein isolated from the obligate anaerobe Clostridium botulinum (Cb H-NOX) was previously reported to bind NO with a femtomolar K(D) (Nioche, P. et al. Science 2004, 306, 1550-1553). On the other hand, no oxyferrous Cb H-NOX was observed despite full conservation of the key residues that stabilize the oxyferrous complex in the H-NOX from Thermoanaerobacter tengcongensis (Tt H-NOX) (the same study). In this study, we re-measured the kinetics/affinities of Cb H-NOX for CO, NO, and O2. K(D)(CO) for the simple one-step equilibrium binding was 1.6 × 10(-7) M. The K(D)(NO) of Cb H-NOX was 8.0 × 10(-11) M for the first six-coordinate NO complex, and the previous femtomolar K(D)(NO) was actually an apparent K(D) for its multiple-step NO binding. An oxyferrous Cb H-NOX was clearly observed with a K(D)(O2) of 5.3 × 10(-5) M, which is significantly higher than Tt H-NOX's K(D)(O2) = 4.4 × 10(-8) M. The gaseous ligand binding of Cb H-NOX provides another supportive example for the "sliding scale rule" hypothesis (Tsai, A.-L. et al. Antioxid. Redox Signal. 2012, 17, 1246-1263), and the presence of hydrogen bond donor Tyr139 in Cb H-NOX selectively enhanced its affinity for oxygen.
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Affiliation(s)
- Gang Wu
- Division of Hematology, Department of Internal Medicine, The University of Texas-Medical School at Houston , 6431 Fannin Street, Houston, Texas 77030, United States
| | - Wen Liu
- Division of Hematology, Department of Internal Medicine, The University of Texas-Medical School at Houston , 6431 Fannin Street, Houston, Texas 77030, United States
| | - Vladimir Berka
- Division of Hematology, Department of Internal Medicine, The University of Texas-Medical School at Houston , 6431 Fannin Street, Houston, Texas 77030, United States
| | - Ah-Lim Tsai
- Division of Hematology, Department of Internal Medicine, The University of Texas-Medical School at Houston , 6431 Fannin Street, Houston, Texas 77030, United States
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13
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Rogers NM, Seeger F, Garcin ED, Roberts DD, Isenberg JS. Regulation of soluble guanylate cyclase by matricellular thrombospondins: implications for blood flow. Front Physiol 2014; 5:134. [PMID: 24772092 PMCID: PMC3983488 DOI: 10.3389/fphys.2014.00134] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 03/18/2014] [Indexed: 01/16/2023] Open
Abstract
Nitric oxide (NO) maintains cardiovascular health by activating soluble guanylate cyclase (sGC) to increase cellular cGMP levels. Cardiovascular disease is characterized by decreased NO-sGC-cGMP signaling. Pharmacological activators and stimulators of sGC are being actively pursued as therapies for acute heart failure and pulmonary hypertension. Here we review molecular mechanisms that modulate sGC activity while emphasizing a novel biochemical pathway in which binding of the matricellular protein thrombospondin-1 (TSP1) to the cell surface receptor CD47 causes inhibition of sGC. We discuss the therapeutic implications of this pathway for blood flow, tissue perfusion, and cell survival under physiologic and disease conditions.
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Affiliation(s)
- Natasha M Rogers
- Department of Medicine, Vascular Medicine Institute, University of Pittsburgh School of Medicine Pittsburgh, PA, USA
| | - Franziska Seeger
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County Baltimore, MD, USA
| | - Elsa D Garcin
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County Baltimore, MD, USA
| | - David D Roberts
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, NIH Bethesda, MD, USA
| | - Jeffrey S Isenberg
- Department of Medicine, Vascular Medicine Institute, University of Pittsburgh School of Medicine Pittsburgh, PA, USA ; Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh School of Medicine Pittsburgh, PA, USA
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14
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Nitric oxide-sensing H-NOX proteins govern bacterial communal behavior. Trends Biochem Sci 2013; 38:566-75. [PMID: 24113192 DOI: 10.1016/j.tibs.2013.08.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 08/26/2013] [Accepted: 08/27/2013] [Indexed: 11/22/2022]
Abstract
Heme-nitric oxide/oxygen binding (H-NOX) domains function as sensors for the gaseous signaling agent nitric oxide (NO) in eukaryotes and bacteria. Mammalian NO signaling is well characterized and involves the H-NOX domain of soluble guanylate cyclase. In bacteria, H-NOX proteins interact with bacterial signaling proteins in two-component signaling systems or in cyclic-di-GMP metabolism. Characterization of several downstream signaling processes has shown that bacterial H-NOX proteins share a common role in controlling important bacterial communal behaviors in response to NO. The H-NOX pathways regulate motility, biofilm formation, quorum sensing, and symbiosis. Here, we review the latest structural and mechanistic studies that have elucidated how H-NOX domains selectively bind NO and transduce ligand binding into conformational changes that modulate activity of signaling partners. Furthermore, we summarize the recent advances in understanding the physiological function and biochemical details of the H-NOX signaling pathways.
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15
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Weinert EE, Phillips-Piro CM, Marletta MA. Porphyrin π-stacking in a heme protein scaffold tunes gas ligand affinity. J Inorg Biochem 2013; 127:7-12. [PMID: 23831583 DOI: 10.1016/j.jinorgbio.2013.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 06/04/2013] [Accepted: 06/05/2013] [Indexed: 10/26/2022]
Abstract
The role of π-stacking in controlling redox and ligand binding properties of porphyrins has been of interest for many years. The recent discovery of H-NOX domains has provided a model system to investigate the role of porphyrin π-stacking within a heme protein scaffold. Removal of a phenylalanine-porphyrin π-stack dramatically increased O2, NO, and CO affinities and caused changes in redox potential (~40mV) without any structural changes. These results suggest that small changes in redox potential affect ligand affinity and that π-stacking may provide a novel route to engineer heme protein properties for new functions.
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Affiliation(s)
- Emily E Weinert
- Department of Chemistry, Emory University, Atlanta, GA 30322, United States
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