1
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Singh S, Gyawali YP, Jiang T, Bukowski GS, Zheng H, Zhang H, Owopetu R, Thielges MC, Feng C. Probing calmodulin-NO synthase interactions via site-specific infrared spectroscopy: an introductory investigation. J Biol Inorg Chem 2024; 29:243-250. [PMID: 38580821 PMCID: PMC11181464 DOI: 10.1007/s00775-024-02046-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/15/2024] [Indexed: 04/07/2024]
Abstract
Calmodulin (CaM) binds to a linker between the oxygenase and reductase domains of nitric oxide synthase (NOS) to regulate the functional conformational dynamics. Specific residues on the interdomain interface guide the domain-domain docking to facilitate the electron transfer in NOS. Notably, the docking interface between CaM and the heme-containing oxygenase domain of NOS is isoform specific, which is only beginning to be investigated. Toward advancing understanding of the distinct CaM-NOS docking interactions by infrared spectroscopy, we introduced a cyano-group as frequency-resolved vibrational probe into CaM individually and when associated with full-length and a bi-domain oxygenase/FMN construct of the inducible NOS isoform (iNOS). Site-specific, selective labeling with p-cyano-L-phenylalanine (CNF) by amber suppression of CaM bound to the iNOS has been accomplished by protein coexpression due to the instability of recombinant iNOS protein alone. We introduced CNF at residue 108, which is at the putative CaM-heme (NOS) docking interface. CNF was also introduced at residue 29, which is distant from the docking interface. FT IR data show that the 108 site is sensitive to CaM-NOS complex formation, while insensitivity to its association with the iNOS protein or peptide was observed for the 29 site. Moreover, narrowing of the IR bands at residue 108 suggests the C≡N probe experiences a more limited distribution of environments, indicating side chain restriction apparent for the complex with iNOS. This initial work sets the stage for residue-specific characterizations of structural dynamics of the docked states of NOS proteins.
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Affiliation(s)
- Swapnil Singh
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Yadav Prasad Gyawali
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Ting Jiang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Gregory S Bukowski
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Huayu Zheng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Haikun Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Rebecca Owopetu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Megan C Thielges
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA.
| | - Changjian Feng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA.
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
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2
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Stewart AM, Shanmugam M, Kutta RJ, Scrutton NS, Lovett JE, Hay S. Combined Pulsed Electron Double Resonance EPR and Molecular Dynamics Investigations of Calmodulin Suggest Effects of Crowding Agents on Protein Structures. Biochemistry 2022; 61:1735-1742. [PMID: 35979922 PMCID: PMC9454100 DOI: 10.1021/acs.biochem.2c00099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Calmodulin (CaM) is a highly dynamic Ca2+-binding
protein
that exhibits large conformational changes upon binding Ca2+ and target proteins. Although it is accepted that CaM exists in
an equilibrium of conformational states in the absence of target protein,
the physiological relevance of an elongated helical linker region
in the Ca2+-replete form has been highly debated. In this
study, we use PELDOR (pulsed electron–electron double resonance)
EPR measurements of a doubly spin-labeled CaM variant to assess the
conformational states of CaM in the apo-, Ca2+-bound, and
Ca2+ plus target peptide-bound states. Our findings are
consistent with a three-state conformational model of CaM, showing
a semi-open apo-state, a highly extended Ca2+-replete state,
and a compact target protein-bound state. Molecular dynamics simulations
suggest that the presence of glycerol, and potentially other molecular
crowding agents, has a profound effect on the relative stability of
the different conformational states. Differing experimental conditions
may explain the discrepancies in the literature regarding the observed
conformational state(s) of CaM, and our PELDOR measurements show good
evidence for an extended conformation of Ca2+-replete CaM
similar to the one observed in early X-ray crystal structures.
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Affiliation(s)
- Andrew M Stewart
- The Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames 50011, Iowa, United States.,Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Muralidharan Shanmugam
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Roger J Kutta
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.,Institute of Physical and Theoretical Chemistry, University of Regensburg, Regensburg 93040, Germany
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Janet E Lovett
- SUPA School of Physics and Astronomy and BSRC, The University of St Andrews, St Andrews KY16 9SS, U.K
| | - Sam Hay
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
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3
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Lawal MM, Vaissier Welborn V. Structural dynamics support electrostatic interactions in the active site of Adenylate Kinase. Chembiochem 2022; 23:e202200097. [PMID: 35303385 DOI: 10.1002/cbic.202200097] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/17/2022] [Indexed: 11/12/2022]
Abstract
Electrostatic preorganization as well as structural and dynamic heterogeneity are often used to rationalize the remarkable catalytic efficiency of enzymes. However, they are often presented as incompatible because the generation of permanent electrostatic effects implies that the protein structure remains rigid. Here, we use a metric, electric fields, that can treat electrostatic contributions and dynamics effects on equal footing, for a unique perspective on enzymatic catalysis. We find that the residues that contribute the most to electrostatic interactions with the substrate in the active site of Adenylate Kinase (our working example) are also the most flexible residues. Further, entropy-tuning mutations raise flexibility at the picosecond timescale where more conformations can be visited on short time periods, thereby softening the sharp heterogeneity normally visible at the microsecond timescale.
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Affiliation(s)
| | - Valerie Vaissier Welborn
- Virginia Polytechnic Institute and State University, Chemistry, Davidson 421A, 1040 Drillfield Drive, 24073, Blacksburg, UNITED STATES
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4
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Lesanavičius M, Boucher JL, Čėnas N. Reactions of Recombinant Neuronal Nitric Oxide Synthase with Redox Cycling Xenobiotics: A Mechanistic Study. Int J Mol Sci 2022; 23:ijms23020980. [PMID: 35055166 PMCID: PMC8781745 DOI: 10.3390/ijms23020980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 12/16/2022] Open
Abstract
Neuronal nitric oxide synthase (nNOS) catalyzes single-electron reduction of quinones (Q), nitroaromatic compounds (ArNO2) and aromatic N-oxides (ArN → O), and is partly responsible for their oxidative stress-type cytotoxicity. In order to expand a limited knowledge on the enzymatic mechanisms of these processes, we aimed to disclose the specific features of nNOS in the reduction of such xenobiotics. In the absence or presence of calmodulin (CAM), the reactivity of Q and ArN → O increases with their single-electron reduction midpoint potential (E17). ArNO2 form a series with lower reactivity. The calculations according to an "outer-sphere" electron transfer model show that the binding of CAM decreases the electron transfer distance from FMNH2 to quinone by 1-2 Å. The effects of ionic strength point to the interaction of oxidants with a negatively charged protein domain close to FMN, and to an increase in accessibility of the active center induced by high ionic strength. The multiple turnover experiments of nNOS show that, in parallel with reduced FAD-FMN, duroquinone reoxidizes the reduced heme, in particular its Fe2+-NO form. This finding may help to design the heme-targeted bioreductively activated agents and contribute to the understanding of the role of P-450-type heme proteins in the bioreduction of quinones and other prooxidant xenobiotics.
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Affiliation(s)
- Mindaugas Lesanavičius
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania;
| | - Jean-Luc Boucher
- Laboratoire de Chimie & Biochimie Pharmacologiques et Toxicologiques, CNRS UMR 8601, Université Paris Descartes, 45 rue de Saints Pères, CEDEX 06, 75270 Paris, France;
| | - Narimantas Čėnas
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania;
- Correspondence: ; Tel.: +370-223-4392
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5
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Zheng H, Li J, Feng C. An isoform-specific pivot modulates the electron transfer between the flavin mononucleotide and heme centers in inducible nitric oxide synthase. J Biol Inorg Chem 2020; 25:1097-1105. [PMID: 33057871 PMCID: PMC7669679 DOI: 10.1007/s00775-020-01824-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 09/24/2020] [Indexed: 11/25/2022]
Abstract
Intraprotein interdomain electron transfer (IET) between the flavin mononucleotide (FMN) and heme centers is an obligatory step in nitric oxide synthase (NOS) enzymes. An isoform-specific pivotal region near Leu406 in the heme domain of human inducible NOS (iNOS) was proposed to mediate the FMN-heme domain-domain alignment (J Inorg Biochem 153:186-196, 2015). The FMN-heme IET rate is a measure of the interdomain FMN/heme complex formation. In this work, the FMN-heme IET kinetics in the wild type (wt) human iNOS oxygenase/FMN (oxyFMN) construct were directly measured by laser flash photolysis with added synthetic peptide related to the pivotal region, in comparison with the wt construct alone. The IET rates were decreased by the iNOS HKL peptide in a dose-saturable fashion, and the inhibitory effect was abolished by a single L406 → E mutation in the peptide. A similar trend in change of the NO synthesis activity of wt iNOS holoenzyme by the peptides was observed. These data, along with the kinetics and modeling results for the L406T and L406F mutant oxyFMN proteins, indicated that the Leu406 residue modulates the FMN-heme IET through hydrophobic interactions. Moreover, the IET rates were analyzed for the wt iNOS oxyFMN protein in the presence of nNOS or eNOS-derived peptide related to the equivalent pivotal heme domain site. These results together indicate that the isoform-specific pivotal region at the heme domain specifically interacts with the conserved FMN domain surface, to facilitate proper interdomain docking for the FMN-heme IET in NOS.
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Affiliation(s)
- Huayu Zheng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Jinghui Li
- College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Changjian Feng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA.
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
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6
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Hedison T, Shenoy RT, Iorgu AI, Heyes DJ, Fisher K, Wright GSA, Hay S, Eady RR, Antonyuk SV, Hasnain SS, Scrutton NS. Unexpected Roles of a Tether Harboring a Tyrosine Gatekeeper Residue in Modular Nitrite Reductase Catalysis. ACS Catal 2019; 9:6087-6099. [PMID: 32051772 PMCID: PMC7007197 DOI: 10.1021/acscatal.9b01266] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/19/2019] [Indexed: 01/26/2023]
Abstract
It is generally assumed that tethering enhances rates of electron harvesting and delivery to active sites in multidomain enzymes by proximity and sampling mechanisms. Here, we explore this idea in a tethered 3-domain, trimeric copper-containing nitrite reductase. By reverse engineering, we find that tethering does not enhance the rate of electron delivery from its pendant cytochrome c to the catalytic copper-containing core. Using a linker that harbors a gatekeeper tyrosine in a nitrite access channel, the tethered haem domain enables catalysis by other mechanisms. Tethering communicates the redox state of the haem to the distant T2Cu center that helps initiate substrate binding for catalysis. It also tunes copper reduction potentials, suppresses reductive enzyme inactivation, enhances enzyme affinity for substrate, and promotes intercopper electron transfer. Tethering has multiple unanticipated beneficial roles, the combination of which fine-tunes function beyond simplistic mechanisms expected from proximity and restrictive sampling models.
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Affiliation(s)
- Tobias
M. Hedison
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Rajesh T. Shenoy
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Andreea I. Iorgu
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Derren J. Heyes
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Karl Fisher
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Gareth S. A. Wright
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Sam Hay
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Robert R. Eady
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Svetlana V. Antonyuk
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - S. Samar Hasnain
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Nigel S. Scrutton
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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7
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Li P, Zhang N, Ping F, Gao Y, Cao L. lncRNA SCAL1 inhibits inducible nitric oxide synthase in lung cells under high-glucose conditions. Exp Ther Med 2019; 18:1831-1836. [PMID: 31410144 DOI: 10.3892/etm.2019.7729] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 04/04/2019] [Indexed: 12/12/2022] Open
Abstract
The lungs are one of the most common target organs of diabetic injury in patients with diabetes. Long non-coding RNA (lncRNA) smoke and cancer-associated lncRNA 1 (SCAL1), also known as lung cancer associated transcript 1 (LUCAT1), is known to have a pivotal role in lung cancer. The aim of the current study was to investigate the potential involvement of SCAL1 in diabetic lung disease. The expression levels of SCAL1 were determined by reverse transcription-quantitative PCR in serum samples from healthy controls (n=40), diabetic patients without lung disease (n=56) and diabetic patients with diabetic lung disease (n=44). Receiver operating characteristic analysis was used to evaluate the diagnostic value of serum SCAL1 in discriminating diabetic patients with diabetic lung disease from diabetic patients without lung disease and healthy controls. Pearson's correlation analysis was performed to examine the correlation between SCAL1 and inducible nitric oxide synthase (iNOS) mRNA expression levels in blood and lung tissue samples. Expression levels of iNOS and NO production following treatment with high (30 mM) glucose were examined by western blot analysis and NO assay, respectively. The expression levels of SCAL1 were significantly downregulated in diabetic patients with diabetic lung disease, and downregulated serum expression levels of SCAL1 effectively distinguished diabetic patients with diabetic lung disease from diabetic patients without lung disease and healthy controls. Treatment with high glucose significantly upregulated SCAL1 expression in normal lung cells. Furthermore, the overexpression of SCAL1 inhibited iNOS protein expression and reduced NO production in cells treated with high glucose. In conclusion, the current study demonstrated that lncRNA SCAL1 inhibits iNOS protein expression in lung cells under high-glucose conditions, which suggests that SCAL1 may have potential in the treatment of patients with diabetic lung disease.
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Affiliation(s)
- Ping Li
- Department of Gerontology, Hebei General Hospital, Shijiazhuang, Hebei 050051, P.R. China
| | - Ning Zhang
- Department of Gerontology, Hebei General Hospital, Shijiazhuang, Hebei 050051, P.R. China
| | - Fen Ping
- Department of Gerontology, Hebei General Hospital, Shijiazhuang, Hebei 050051, P.R. China
| | - Yanfeng Gao
- Department of Gerontology, Hebei General Hospital, Shijiazhuang, Hebei 050051, P.R. China
| | - Lei Cao
- Department of Gerontology, Hebei General Hospital, Shijiazhuang, Hebei 050051, P.R. China
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8
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Li J, Zheng H, Feng C. Effect of Macromolecular Crowding on the FMN-Heme Intraprotein Electron Transfer in Inducible NO Synthase. Biochemistry 2019; 58:3087-3096. [PMID: 31251033 DOI: 10.1021/acs.biochem.9b00193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Previous biochemical studies of nitric oxide synthase enzymes (NOSs) were conducted in diluted solutions. However, the intracellular milieu where the proteins perform their biological functions is crowded with macromolecules. The effect of crowding on the electron transfer kinetics of multidomain proteins is much less understood. Herein, we investigated the effect of macromolecular crowding on the FMN-heme intraprotein interdomain electron transfer (IET), an obligatory step in NOS catalysis. A noticeable increase in the IET rate in the bidomain oxygenase/FMN (oxyFMN) and the holoprotein of human inducible NOS (iNOS) was observed upon addition of Ficoll 70 in a nonsaturable manner. Additionally, the magnitude of IET enhancement for the holoenzyme is much higher than that that of the oxyFMN construct. The crowding effect is also evident at different ionic strengths. Importantly, the enhancing extent is similar for the iNOS oxyFMN protein with added Ficoll 70 and Dextran 70 that give the same solution viscosity, showing that specific interactions do not exist between the NOS protein and the crowder. Moreover, the population of the docked FMN-heme state is significantly increased upon addition of Ficoll 70 and the fluorescence lifetime values do not correspond to those in the absence of Ficoll 70. The steady-state cytochrome c reduction by the holoenzyme is noticeably enhanced by the crowder, while the ferricyanide reduction is unchanged. The NO production activity of the iNOS holoenzyme is stimulated by Ficoll 70. The effect of macromolecular crowding on the kinetics can be rationalized on the basis of the excluded volume effect, with an entropic origin. The intraprotein electron transfer kinetics, fluorescence lifetime, and steady-state enzymatic activity results indicate that macromolecular crowding modulates the NOS electron transfer through multiple pathways. Such a mechanism should be applicable to electron transfer in other multidomain redox proteins.
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Affiliation(s)
- Jinghui Li
- College of Pharmacy , University of New Mexico , Albuquerque , New Mexico 87131 , United States
| | - Huayu Zheng
- College of Pharmacy , University of New Mexico , Albuquerque , New Mexico 87131 , United States.,Department of Chemistry and Chemical Biology , University of New Mexico , Albuquerque , New Mexico 87131 , United States
| | - Changjian Feng
- College of Pharmacy , University of New Mexico , Albuquerque , New Mexico 87131 , United States.,Department of Chemistry and Chemical Biology , University of New Mexico , Albuquerque , New Mexico 87131 , United States
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9
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Bignon E, Rizza S, Filomeni G, Papaleo E. Use of Computational Biochemistry for Elucidating Molecular Mechanisms of Nitric Oxide Synthase. Comput Struct Biotechnol J 2019; 17:415-429. [PMID: 30996821 PMCID: PMC6451115 DOI: 10.1016/j.csbj.2019.03.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/17/2019] [Accepted: 03/21/2019] [Indexed: 12/25/2022] Open
Abstract
Nitric oxide (NO) is an essential signaling molecule in the regulation of multiple cellular processes. It is endogenously synthesized by NO synthase (NOS) as the product of L-arginine oxidation to L-citrulline, requiring NADPH, molecular oxygen, and a pterin cofactor. Two NOS isoforms are constitutively present in cells, nNOS and eNOS, and a third is inducible (iNOS). Despite their biological relevance, the details of their complex structural features and reactivity mechanisms are still unclear. In this review, we summarized the contribution of computational biochemistry to research on NOS molecular mechanisms. We described in detail its use in studying aspects of structure, dynamics and reactivity. We also focus on the numerous outstanding questions in the field that could benefit from more extensive computational investigations.
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Affiliation(s)
- Emmanuelle Bignon
- Computational Biology Laboratory, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen, Denmark
| | - Salvatore Rizza
- Redox Signaling and Oxidative Stress Group, Cell Stress and Survival Unit, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen, Denmark
| | - Giuseppe Filomeni
- Redox Signaling and Oxidative Stress Group, Cell Stress and Survival Unit, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen, Denmark.,Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Elena Papaleo
- Computational Biology Laboratory, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen, Denmark.,Translational Disease Systems Biology, Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research University of Copenhagen, Copenhagen, Denmark
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10
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Hedison TM, Scrutton NS. Tripping the light fantastic in membrane redox biology: linking dynamic structures to function in ER electron transfer chains. FEBS J 2019; 286:2004-2017. [PMID: 30657259 PMCID: PMC6563164 DOI: 10.1111/febs.14757] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 12/16/2018] [Accepted: 01/15/2019] [Indexed: 12/19/2022]
Abstract
How the dynamics of proteins assist catalysis is a contemporary issue in enzymology. In particular, this holds true for membrane‐bound enzymes, where multiple structural, spectroscopic and biochemical approaches are needed to build up a comprehensive picture of how dynamics influence enzyme reaction cycles. Of note are the recent studies of cytochrome P450 reductases (CPR)–P450 (CYP) endoplasmic reticulum redox chains, showing the relationship between dynamics and electron flow through flavin and haem redox centres and the impact this has on monooxygenation chemistry. These studies have led to deeper understanding of mechanisms of electron flow, including the timing and control of electron delivery to protein‐bound cofactors needed to facilitate CYP‐catalysed reactions. Individual and multiple component systems have been used to capture biochemical behaviour and these have led to the emergence of more integrated models of catalysis. Crucially, the effects of membrane environment and composition on reaction cycle chemistry have also been probed, including effects on coenzyme binding/release, thermodynamic control of electron transfer, conformational coupling between partner proteins and vectorial versus ‘off pathway’ electron flow. Here, we review these studies and discuss evidence for the emergence of dynamic structural models of electron flow along human microsomal CPR–P450 redox chains.
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Affiliation(s)
- Tobias M Hedison
- Manchester Institute of Biotechnology and School of Chemistry, University of Manchester, UK
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology and School of Chemistry, University of Manchester, UK
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11
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Molecular mechanism of metabolic NAD(P)H-dependent electron-transfer systems: The role of redox cofactors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1860:233-258. [PMID: 30419202 DOI: 10.1016/j.bbabio.2018.11.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 10/30/2018] [Accepted: 11/07/2018] [Indexed: 12/14/2022]
Abstract
NAD(P)H-dependent electron-transfer (ET) systems require three functional components: a flavin-containing NAD(P)H-dehydrogenase, one-electron carrier and metal-containing redox center. In principle, these ET systems consist of one-, two- and three-components, and the electron flux from pyridine nucleotide cofactors, NADPH or NADH to final electron acceptor follows a linear pathway: NAD(P)H → flavin → one-electron carrier → metal containing redox center. In each step ET is primarily controlled by one- and two-electron midpoint reduction potentials of protein-bound redox cofactors in which the redox-linked conformational changes during the catalytic cycle are required for the domain-domain interactions. These interactions play an effective ET reactions in the multi-component ET systems. The microsomal and mitochondrial cytochrome P450 (cyt P450) ET systems, nitric oxide synthase (NOS) isozymes, cytochrome b5 (cyt b5) ET systems and methionine synthase (MS) ET system include a combination of multi-domain, and their organizations display similarities as well as differences in their components. However, these ET systems are sharing of a similar mechanism. More recent structural information obtained by X-ray and cryo-electron microscopy (cryo-EM) analysis provides more detail for the mechanisms associated with multi-domain ET systems. Therefore, this review summarizes the roles of redox cofactors in the metabolic ET systems on the basis of one-electron redox potentials. In final Section, evolutionary aspects of NAD(P)H-dependent multi-domain ET systems will be discussed.
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12
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Li J, Zheng H, Wang W, Miao Y, Sheng Y, Feng C. Role of an isoform-specific residue at the calmodulin-heme (NO synthase) interface in the FMN - heme electron transfer. FEBS Lett 2018; 592:2425-2431. [PMID: 29904908 DOI: 10.1002/1873-3468.13158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/31/2018] [Accepted: 06/05/2018] [Indexed: 12/18/2022]
Abstract
The interface between calmodulin (CaM) and the NO synthase (NOS) heme domain is the least characterized interprotein interface that the NOS isoforms must traverse through during catalysis. Our previous molecular dynamics simulations predicted a salt bridge between K497 in human inducible NOS (iNOS) heme domain and D118(CaM). Herein, the FMN - heme interdomain electron transfer (IET) rate was found to be notably decreased by charge-reversal mutation, while the IET in the iNOS K497D mutant is significantly restored by the CaM D118K mutation. The results of wild-type protein with added synthetic peptides further demonstrate the critical nature of K497 relative to the rest of the peptide sequence in modulating the IET. These data provide definitive evidence supporting the regulatory role of the isoform-specific K497 residue.
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Affiliation(s)
- Jinghui Li
- College of Pharmacy, University of New Mexico, Albuquerque, NM, USA
| | - Huayu Zheng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, USA.,Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, USA
| | - Wei Wang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, USA
| | - Yubin Miao
- Department of Radiology, School of Medicine, University of Colorado Denver, Aurora, CO, USA
| | - Yinghong Sheng
- Department of Chemistry & Physics, College of Arts & Sciences, Florida Gulf Coast University, Fort Myers, FL, USA
| | - Changjian Feng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, USA.,Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, USA
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13
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Arnett DC, Bailey SK, Johnson CK. Exploring the conformations of nitric oxide synthase with fluorescence. Front Biosci (Landmark Ed) 2018; 23:2133-2145. [PMID: 29772550 DOI: 10.2741/4694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Multi-domain oxidoreductases are a family of enzymes that catalyze oxidation-reduction reactions through a series of electron transfers. Efficient electron transfer requires a sequence of protein conformations that position electron donor and acceptor domains in close proximity to each other so that electron transfer can occur efficiently. An example is mammalian nitric oxide synthase (NOS), which consists of an N-terminal oxygenase domain containing heme and a C-terminal reductase domain containing NADPH/FAD and FMN subdomains. We describe the use of time-resolved and single-molecule fluorescence to detect and characterize the conformations and conformational dynamics of the neuronal and endothelial isoforms of NOS. Fluorescence signals are provided by a fluorescent dye attached to the Ca2+-signaling protein calmodulin (CaM), which regulates NOS activity. Time-resolved fluorescence decays reveal the presence of at least four underlying conformational states that are differentiated by the extent of fluorescence quenching. Single-molecule fluorescence displays transitions between conformational states on the time scales of milliseconds to seconds. This review describes the type of information available by analysis of time-resolved and single-molecule fluorescence experiments.
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Affiliation(s)
- David C Arnett
- Department of Chemistry, Northwestern College, 101 7th Street SW, Orange City, IA 51041
| | - Sheila K Bailey
- Department of Chemistry, University of Kansas, 1251 Wescoe Drive, Lawrence, KS 66045
| | - Carey K Johnson
- Department of Chemistry, University of Kansas, 1251 Wescoe Drive, Lawrence, KS 66045,
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14
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Hedison TM, Hay S, Scrutton NS. A perspective on conformational control of electron transfer in nitric oxide synthases. Nitric Oxide 2017; 63:61-67. [PMID: 27619338 PMCID: PMC5295631 DOI: 10.1016/j.niox.2016.09.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 01/20/2023]
Abstract
This perspective reviews single molecule and ensemble fluorescence spectroscopy studies of the three tissue specific nitric oxide synthase (NOS) isoenzymes and the related diflavin oxidoreductase cytochrome P450 reductase. The focus is on the role of protein dynamics and the protein conformational landscape and we discuss how recent fluorescence-based studies have helped in illustrating how the nature of the NOS conformational landscape relates to enzyme turnover and catalysis.
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Affiliation(s)
- Tobias M Hedison
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom
| | - Sam Hay
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom.
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15
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Dai Y, Haque MM, Stuehr DJ. Restricting the conformational freedom of the neuronal nitric-oxide synthase flavoprotein domain reveals impact on electron transfer and catalysis. J Biol Chem 2017; 292:6753-6764. [PMID: 28232486 DOI: 10.1074/jbc.m117.777219] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/16/2017] [Indexed: 01/02/2023] Open
Abstract
The signaling molecule nitric oxide (NO) is synthesized in animals by structurally related NO synthases (NOSs), which contain NADPH/FAD- and FMN-binding domains. During catalysis, NADPH-derived electrons transfer into FAD and then distribute into the FMN domain for further transfer to internal or external heme groups. Conformational freedom of the FMN domain is thought to be essential for the electron transfer (ET) reactions in NOSs. To directly examine this concept, we utilized a "Cys-lite" neuronal NOS flavoprotein domain and substituted Cys for two residues (Glu-816 and Arg-1229) forming a salt bridge between the NADPH/FAD and FMN domains in the conformationally closed structure to allow cross-domain disulfide bond formation or cross-linking by bismaleimides of various lengths. The disulfide bond cross-link caused a ≥95% loss of cytochrome c reductase activity that was reversible with DTT treatment, whereas graded cross-link lengthening gradually increased activity, thus defining the conformational constraints in the catalytic process. We used spectroscopic and stopped-flow techniques to further investigate how the changes in FMN domain conformational freedom impact the following: (i) the NADPH interaction; (ii) kinetics of electron loading (flavin reduction); (iii) stabilization of open versus closed conformational forms in two different flavin redox states; (iv) reactivity of the reduced FMN domain toward cytochrome c; (v) response to calmodulin binding; and (vi) the rates of interflavin ET and the FMN domain conformational dynamics. Together, our findings help explain how the spatial and temporal behaviors of the FMN domain impact catalysis by the NOS flavoprotein domain and how these behaviors are governed to enable electron flow through the enzyme.
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Affiliation(s)
- Yue Dai
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195 and.,the Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115
| | - Mohammad Mahfuzul Haque
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195 and
| | - Dennis J Stuehr
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195 and
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16
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Piazza M, Taiakina V, Dieckmann T, Guillemette JG. Structural Consequences of Calmodulin EF Hand Mutations. Biochemistry 2017; 56:944-956. [PMID: 28121131 DOI: 10.1021/acs.biochem.6b01296] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calmodulin (CaM) is a cytosolic Ca2+-binding protein that serves as a control element for many enzymes. It consists of two globular domains, each containing two EF hand pairs capable of binding Ca2+, joined by a flexible central linker region. CaM is able to bind and activate its target proteins in the Ca2+-replete and Ca2+-deplete forms. To study the Ca2+-dependent/independent properties of binding and activation of target proteins by CaM, CaM constructs with Ca2+-binding disrupting mutations of Asp to Ala at position one of each EF hand have been used. These CaM mutant proteins are deficient in binding Ca2+ in either the N-lobe EF hands (CaM12), C-lobe EF hands (CaM34), or all four EF hands (CaM1234). To investigate potential structural changes these mutations may cause, we performed detailed NMR studies of CaM12, CaM34, and CaM1234 including determining the solution structure of CaM1234. We then investigated if these CaM mutants affected the interaction of CaM with a target protein known to interact with apoCaM by determining the solution structure of CaM34 bound to the iNOS CaM binding domain peptide. The structures provide direct structural evidence of changes that are present in these Ca2+-deficient CaM mutants and show these mutations increase the hydrophobic exposed surface and decrease the electronegative surface potential throughout each lobe of CaM. These Ca2+-deficient CaM mutants may not be a true representation of apoCaM and may not allow for native-like interactions of apoCaM with its target proteins.
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Affiliation(s)
- Michael Piazza
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Valentina Taiakina
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Thorsten Dieckmann
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - J Guy Guillemette
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
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17
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Li B, Tian X, Wang C, Zeng X, Xing Y, Ling H, Yin W, Tian L, Meng Z, Zhang J, Guo S. SWATH label-free proteomics analyses revealed the roles of oxidative stress and antioxidant defensing system in sclerotia formation of Polyporus umbellatus. Sci Rep 2017; 7:41283. [PMID: 28134344 PMCID: PMC5278369 DOI: 10.1038/srep41283] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 12/19/2016] [Indexed: 02/03/2023] Open
Abstract
Understanding the initiation and maturing mechanisms is important for rational manipulating sclerotia differentiation and growth from hypha of Polyporus umbellatus. Proteomes in P. umbellatus sclerotia and hyphae at initial, developmental and mature phases were studied. 1391 proteins were identified by nano-liquid chromatograph-mass spectrometry (LC-MS) in Data Dependant Acquisition mode, and 1234 proteins were quantified successfully by Sequential Window Acquisition of all THeoretical fragment ion spectra-MS (SWATH-MS) technology. There were 347 differentially expressed proteins (DEPs) in sclerotia at initial phase compared with those in hypha, and the DEP profiles were dynamically changing with sclerotia growth. Oxidative stress (OS) in sclerotia at initial phase was indicated by the repressed proteins of respiratory chain, tricarboxylic acid cycle and the activation of glycolysis/gluconeogenesis pathways were determined based on DEPs. The impact of glycolysis/gluconeogenesis on sclerotium induction was further verified by glycerol addition assays, in which 5% glycerol significantly increased sclerotial differentiation rate and biomass. It can be speculated that OS played essential roles in triggering sclerotia differentiation from hypha of P. umbellatus, whereas antioxidant activity associated with glycolysis is critical for sclerotia growth. These findings reveal a mechanism for sclerotial differentiation in P. umbellatus, which may also be applicable for other fungi.
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Affiliation(s)
- Bing Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
| | - Xiaofang Tian
- Pharmaceutical department of China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - Chunlan Wang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
| | - Xu Zeng
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
| | - Yongmei Xing
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
| | - Hong Ling
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
| | - Wanqiang Yin
- Tianjin University of Science & Technology, Tianjin 300457, P. R. China
| | - Lixia Tian
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
| | - Zhixia Meng
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
| | - Jihui Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Shunxing Guo
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193 P. R. China
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18
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Piazza M, Dieckmann T, Guillemette JG. Structural Studies of a Complex Between Endothelial Nitric Oxide Synthase and Calmodulin at Physiological Calcium Concentration. Biochemistry 2016; 55:5962-5971. [DOI: 10.1021/acs.biochem.6b00821] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael Piazza
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Thorsten Dieckmann
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - J. Guy Guillemette
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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19
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Haque MM, Ray SS, Stuehr DJ. Phosphorylation Controls Endothelial Nitric-oxide Synthase by Regulating Its Conformational Dynamics. J Biol Chem 2016; 291:23047-23057. [PMID: 27613870 DOI: 10.1074/jbc.m116.737361] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Indexed: 11/06/2022] Open
Abstract
The activity of endothelial NO synthase (eNOS) is triggered by calmodulin (CaM) binding and is often further regulated by phosphorylation at several positions in the enzyme. Phosphorylation at Ser1179 occurs in response to diverse physiologic stimuli and increases the NO synthesis and cytochrome c reductase activities of eNOS, thereby enhancing its participation in biological signal cascades. Despite its importance, the mechanism by which Ser1179 phosphorylation increases eNOS activity is not understood. To address this, we used stopped-flow spectroscopy and computer modeling approaches to determine how the phosphomimetic mutation (S1179D) may impact electron flux through eNOS and the conformational behaviors of its reductase domain, both in the absence and presence of bound CaM. We found that S1179D substitution in CaM-free eNOS had multiple effects; it increased the rate of flavin reduction, altered the conformational equilibrium of the reductase domain, and increased the rate of its conformational transitions. We found these changes were equivalent in degree to those caused by CaM binding to wild-type eNOS, and the S1179D substitution together with CaM binding caused even greater changes in these parameters. The modeling indicated that the changes caused by the S1179D substitution, despite being restricted to the reductase domain, are sufficient to explain the stimulation of both the cytochrome c reductase and NO synthase activities of eNOS. This helps clarify how Ser1179 phosphorylation regulates eNOS and provides a foundation to compare its regulation by other phosphorylation events.
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Affiliation(s)
- Mohammad Mahfuzul Haque
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Sougata Sinha Ray
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Dennis J Stuehr
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
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20
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Hedison TM, Leferink NGH, Hay S, Scrutton NS. Correlating Calmodulin Landscapes with Chemical Catalysis in Neuronal Nitric Oxide Synthase using Time-Resolved FRET and a 5-Deazaflavin Thermodynamic Trap. ACS Catal 2016; 6:5170-5180. [PMID: 27563493 PMCID: PMC4993522 DOI: 10.1021/acscatal.6b01280] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 06/23/2016] [Indexed: 11/28/2022]
Abstract
![]()
A major challenge in enzymology is
the need to correlate the dynamic
properties of enzymes with, and understand the impact on, their catalytic
cycles. This is especially the case with large, multicenter enzymes
such as the nitric oxide synthases (NOSs), where the importance of
dynamics has been inferred from a variety of structural, single-molecule,
and ensemble spectroscopic approaches but where motions have not been
correlated experimentally with mechanistic steps in the reaction cycle.
Here we take such an approach. Using time-resolved spectroscopy employing
absorbance and Förster resonance energy transfer (FRET) and
exploiting the properties of a flavin analogue (5-deazaflavin mononucleotide
(5-dFMN)) and isotopically labeled nicotinamide coenzymes, we correlate
the timing of CaM structural changes when bound to neuronal nitric
oxide synthase (nNOS) with the nNOS catalytic cycle. We show that
remodeling of CaM occurs early in the electron transfer sequence (FAD
reduction), not at later points in the reaction cycle (e.g., FMN reduction).
Conformational changes are tightly correlated with FAD reduction kinetics
and reflect a transient “opening” and then “closure”
of the bound CaM molecule. We infer that displacement of the C-terminal
tail on binding NADPH and subsequent FAD reduction are the likely
triggers of conformational change. By combining the use of cofactor/coenzyme
analogues and time-resolved FRET/absorbance spectrophotometry, we
show how the reaction cycles of complex enzymes can be simplified,
enabling a detailed study of the relationship between protein dynamics
and reaction cycle chemistry—an approach that can also be used
with other complex multicenter enzymes.
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Affiliation(s)
- Tobias M. Hedison
- Manchester Synthetic Biology
Research Centre for Fine and Speciality Chemicals (SYNBIOCHEM), Manchester
Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Nicole G. H. Leferink
- Manchester Synthetic Biology
Research Centre for Fine and Speciality Chemicals (SYNBIOCHEM), Manchester
Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Sam Hay
- Manchester Synthetic Biology
Research Centre for Fine and Speciality Chemicals (SYNBIOCHEM), Manchester
Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Nigel S. Scrutton
- Manchester Synthetic Biology
Research Centre for Fine and Speciality Chemicals (SYNBIOCHEM), Manchester
Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
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21
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Astashkin AV, Feng C. Solving Kinetic Equations for the Laser Flash Photolysis Experiment on Nitric Oxide Synthases: Effect of Conformational Dynamics on the Interdomain Electron Transfer. J Phys Chem A 2015; 119:11066-75. [PMID: 26477677 DOI: 10.1021/acs.jpca.5b08414] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The production of nitric oxide by the nitric oxide synthase (NOS) enzyme depends on the interdomain electron transfer (IET) between the flavin mononucleotide (FMN) and heme domains. Although the rate of this IET has been measured by laser flash photolysis (LFP) for various NOS proteins, no rigorous analysis of the relevant kinetic equations was performed so far. In this work, we provide an analytical solution of the kinetic equations underlying the LFP approach. The derived expressions reveal that the bulk IET rate is significantly affected by the conformational dynamics that determines the formation and dissociation rates of the docking complex between the FMN and heme domains. We show that in order to informatively study the electron transfer across the NOS enzyme, LFP should be used in combination with other spectroscopic methods that could directly probe the docking equilibrium and the conformational change rate constants. The implications of the obtained analytical expressions for the interpretation of the LFP results from various native and modified NOS proteins are discussed. The mathematical formulas derived in this work should also be applicable for interpreting the IET kinetics in other modular redox enzymes.
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Affiliation(s)
- Andrei V Astashkin
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Changjian Feng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico , Albuquerque, New Mexico 87131, United States
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22
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Chaiyen P, Scrutton NS. Special Issue: Flavins and Flavoproteins: Introduction. FEBS J 2015; 282:3001-2. [PMID: 26096566 DOI: 10.1111/febs.13337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 06/04/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Pimchai Chaiyen
- Department of Biochemistry and Center of Excellence in Protein Structure & Function, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, UK
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23
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Arnett DC, Persechini A, Tran QK, Black DJ, Johnson CK. Fluorescence quenching studies of structure and dynamics in calmodulin-eNOS complexes. FEBS Lett 2015; 589:1173-8. [PMID: 25871521 DOI: 10.1016/j.febslet.2015.03.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/17/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
Abstract
Activation of endothelial nitric oxide synthase (eNOS) by calmodulin (CaM) facilitates formation of a sequence of conformational states that is not well understood. Fluorescence decays of fluorescently labeled CaM bound to eNOS reveal four distinct conformational states and single-molecule fluorescence trajectories show multiple fluorescence states with transitions between states occurring on time scales of milliseconds to seconds. A model is proposed relating fluorescence quenching states to enzyme conformations. Specifically, we propose that the most highly quenched state corresponds to CaM docked to an oxygenase domain of the enzyme. In single-molecule trajectories, this state occurs with time lags consistent with the oxygenase activity of the enzyme.
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Affiliation(s)
- David C Arnett
- Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA; Department of Chemistry, Northwestern College, Orange City, IA 51041, USA
| | - Anthony Persechini
- Division of Molecular Biology and Biochemistry and Division of Cell Biology and Biophysics, University of Missouri at Kansas City, Kansas City, MO 64410, USA
| | - Quang-Kim Tran
- Division of Molecular Biology and Biochemistry and Division of Cell Biology and Biophysics, University of Missouri at Kansas City, Kansas City, MO 64410, USA
| | - D J Black
- Division of Molecular Biology and Biochemistry and Division of Cell Biology and Biophysics, University of Missouri at Kansas City, Kansas City, MO 64410, USA
| | - Carey K Johnson
- Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA.
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