1
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Zhang Z, Cai Y, Zheng N, Deng Y, Gao L, Wang Q, Xia X. Diverse models of cavity engineering in enzyme modification: Creation, filling, and reshaping. Biotechnol Adv 2024; 72:108346. [PMID: 38518963 DOI: 10.1016/j.biotechadv.2024.108346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 03/07/2024] [Accepted: 03/19/2024] [Indexed: 03/24/2024]
Abstract
Most enzyme modification strategies focus on designing the active sites or their surrounding structures. Interestingly, a large portion of the enzymes (60%) feature active sites located within spacious cavities. Despite recent discoveries, cavity-mediated enzyme engineering remains crucial for enhancing enzyme properties and unraveling folding-unfolding mechanisms. Cavity engineering influences enzyme stability, catalytic activity, specificity, substrate recognition, and docking. This article provides a comprehensive review of various cavity engineering models for enzyme modification, including cavity creation, filling, and reshaping. Additionally, it also discusses feasible tools for geometric analysis, functional assessment, and modification of cavities, and explores potential future research directions in this field. Furthermore, a promising universal modification strategy for cavity engineering that leverages state-of-the-art technologies and methodologies to tailor cavities according to the specific requirements of industrial production conditions is proposed.
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Affiliation(s)
- Zehua Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
| | - Yongchao Cai
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
| | - Nan Zheng
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
| | - Yu Deng
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
| | - Ling Gao
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
| | - Qiong Wang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
| | - Xiaole Xia
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China; College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, PR China.
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2
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Abdullin D, Rauh Corro P, Hett T, Schiemann O. PDSFit: PDS data analysis in the presence of orientation selectivity, g-anisotropy, and exchange coupling. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:37-60. [PMID: 38130168 DOI: 10.1002/mrc.5415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/24/2023] [Accepted: 11/01/2023] [Indexed: 12/23/2023]
Abstract
Pulsed dipolar electron paramagnetic resonance spectroscopy (PDS), encompassing techniques such as pulsed electron-electron double resonance (PELDOR or DEER) and relaxation-induced dipolar modulation enhancement (RIDME), is a valuable method in structural biology and materials science for obtaining nanometer-scale distance distributions between electron spin centers. An important aspect of PDS is the extraction of distance distributions from the measured time traces. Most software used for this PDS data analysis relies on simplifying assumptions, such as assuming isotropic g-factors of ~2 and neglecting orientation selectivity and exchange coupling. Here, the program PDSFit is introduced, which enables the analysis of PELDOR and RIDME time traces with or without orientation selectivity. It can be applied to spin systems consisting of up to two spin centers with anisotropic g-factors and to spin systems with exchange coupling. It employs a model-based fitting of the time traces using parametrized distance and angular distributions, and parametrized PDS background functions. The fitting procedure is followed by an error analysis for the optimized parameters of the distributions and backgrounds. Using five different experimental data sets published previously, the performance of PDSFit is tested and found to provide reliable solutions.
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Affiliation(s)
- Dinar Abdullin
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Pablo Rauh Corro
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Tobias Hett
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Olav Schiemann
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
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3
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He J, Dmochowski IJ. Local Xenon-Protein Interaction Produces Global Conformational Change and Allosteric Inhibition in Lysozyme. Biochemistry 2023; 62:1659-1669. [PMID: 37192381 PMCID: PMC10821772 DOI: 10.1021/acs.biochem.3c00046] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Noble gases have well-established biological effects, yet their molecular mechanisms remain poorly understood. Here, we investigated, both experimentally and computationally, the molecular modes of xenon (Xe) action in bacteriophage T4 lysozyme (T4L). By combining indirect gassing methods with a colorimetric lysozyme activity assay, a reversible, Xe-specific (20 ± 3)% inhibition effect was observed. Accelerated molecular dynamic simulations revealed that Xe exerts allosteric inhibition on the protein by expanding a C-terminal hydrophobic cavity. Xe-induced cavity expansion results in global conformational changes, with long-range transduction distorting the active site where peptidoglycan binds. Interestingly, the peptide substrate binding site that enables lysozyme specificity does not change conformation. Two T4L mutants designed to reshape the C-terminal Xe cavity established a correlation between cavity expansion and enzyme inhibition. This work also highlights the use of Xe flooding simulations to identify new cryptic binding pockets. These results enrich our understanding of Xe-protein interactions at the molecular level and inspire further biochemical investigations with noble gases.
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Affiliation(s)
- Jiayi He
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Ivan J Dmochowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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4
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Pillai AS, Hochberg GK, Thornton JW. Simple mechanisms for the evolution of protein complexity. Protein Sci 2022; 31:e4449. [PMID: 36107026 PMCID: PMC9601886 DOI: 10.1002/pro.4449] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/01/2022] [Accepted: 09/10/2022] [Indexed: 01/26/2023]
Abstract
Proteins are tiny models of biological complexity: specific interactions among their many amino acids cause proteins to fold into elaborate structures, assemble with other proteins into higher-order complexes, and change their functions and structures upon binding other molecules. These complex features are classically thought to evolve via long and gradual trajectories driven by persistent natural selection. But a growing body of evidence from biochemistry, protein engineering, and molecular evolution shows that naturally occurring proteins often exist at or near the genetic edge of multimerization, allostery, and even new folds, so just one or a few mutations can trigger acquisition of these properties. These sudden transitions can occur because many of the physical properties that underlie these features are present in simpler proteins as fortuitous by-products of their architecture. Moreover, complex features of proteins can be encoded by huge arrays of sequences, so they are accessible from many different starting points via many possible paths. Because the bridges to these features are both short and numerous, random chance can join selection as a key factor in explaining the evolution of molecular complexity.
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Affiliation(s)
- Arvind S. Pillai
- Department of Ecology and EvolutionUniversity of ChicagoChicagoIllinoisUSA
- Institute for Protein DesignUniversity of WashingtonSeattleWAUSA
| | - Georg K.A. Hochberg
- Max Planck Institute for Terrestrial MicrobiologyMarburgGermany
- Department of Chemistry, Center for Synthetic MicrobiologyPhilipps University MarburgMarburgGermany
| | - Joseph W. Thornton
- Department of Ecology and EvolutionUniversity of ChicagoChicagoIllinoisUSA
- Departments of Human Genetics and Ecology and EvolutionUniversity of ChicagoChicagoIllinoisUSA
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5
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Golla H, Kannan A, Gopi S, Murugan S, Perumalsamy LR, Naganathan AN. Structural-Energetic Basis for Coupling between Equilibrium Fluctuations and Phosphorylation in a Protein Native Ensemble. ACS CENTRAL SCIENCE 2022; 8:282-293. [PMID: 35233459 PMCID: PMC8880421 DOI: 10.1021/acscentsci.1c01548] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Indexed: 06/14/2023]
Abstract
The functioning of proteins is intimately tied to their fluctuations in the native ensemble. The structural-energetic features that determine fluctuation amplitudes and hence the shape of the underlying landscape, which in turn determine the magnitude of the functional output, are often confounded by multiple variables. Here, we employ the FF1 domain from human p190A RhoGAP protein as a model system to uncover the molecular basis for phosphorylation of a buried tyrosine, which is crucial to the transcriptional activity associated with transcription factor TFII-I. Combining spectroscopy, calorimetry, statistical-mechanical modeling, molecular simulations, and in vitro phosphorylation assays, we show that the FF1 domain samples a diverse array of conformations in its native ensemble, some of which are phosphorylation-competent. Upon eliminating unfavorable charge-charge interactions through a single charge-reversal (K53E) or charge-neutralizing (K53Q) mutation, we observe proportionately lower phosphorylation extents due to the altered structural coupling, damped equilibrium fluctuations, and a more compact native ensemble. We thus establish a conformational selection mechanism for phosphorylation in the FF1 domain with K53 acting as a "gatekeeper", modulating the solvent exposure of the buried tyrosine. Our work demonstrates the role of unfavorable charge-charge interactions in governing functional events through the modulation of native ensemble characteristics, a feature that could be prevalent in ordered protein domains.
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Affiliation(s)
- Hemashree Golla
- Department
of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Adithi Kannan
- Department
of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Soundhararajan Gopi
- Department
of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sowmiya Murugan
- Department
of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Lakshmi R Perumalsamy
- Department
of Biomedical Sciences, Sri Ramachandra
Institute of Higher Education and Research, Chennai 600116, India
| | - Athi N. Naganathan
- Department
of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
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6
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Barletta GP, Barletta M, Saldaño TE, Fernandez-Alberti S. Analysis of changes of cavity volumes in predefined directions of protein motions and cavity flexibility. J Comput Chem 2021; 43:391-401. [PMID: 34962296 DOI: 10.1002/jcc.26799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 12/13/2021] [Indexed: 11/12/2022]
Abstract
Dynamics of protein cavities associated with protein fluctuations and conformational plasticity is essential for their biological function. NMR ensembles, molecular dynamics (MD) simulations, and normal mode analysis (NMA) provide appropriate frameworks to explore functionally relevant protein dynamics and cavity changes relationships. Within this context, we have recently developed analysis of null areas (ANA), an efficient method to calculate cavity volumes. ANA is based on a combination of algorithms that guarantees its robustness against numerical differentiations. This is a unique feature with respect to other methods. Herein, we present an updated and improved version that expands it use to quantify changes in cavity features, like volume and flexibility, due to protein structural distortions performed on predefined biologically relevant directions, for example, directions of largest contribution to protein fluctuations (principal component analysis [PCA modes]) obtained by MD simulations or ensembles of NMR structures, collective NMA modes or any other direction of motion associated with specific conformational changes. A web page has been developed where its facilities are explained in detail. First, we show that ANA can be useful to explore gradual changes of cavity volume and flexibility associated with protein ligand binding. Secondly, we perform a comparison study of the extent of variability between protein backbone structural distortions, and changes in cavity volumes and flexibilities evaluated for an ensemble of NMR active and inactive conformers of the epidermal growth factor receptor structures. Finally, we compare changes in size and flexibility between sets of NMR structures for different homologous chains of dynein.
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Affiliation(s)
- German P Barletta
- Unidad de Fisicoquímica, Universidad Nacional de Quilmes/CONICET, Bernal, Argentina
| | | | - Tadeo E Saldaño
- Unidad de Fisicoquímica, Universidad Nacional de Quilmes/CONICET, Bernal, Argentina
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7
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Bradford SYC, El Khoury L, Ge Y, Osato M, Mobley DL, Fischer M. Temperature artifacts in protein structures bias ligand-binding predictions. Chem Sci 2021; 12:11275-11293. [PMID: 34667539 PMCID: PMC8447925 DOI: 10.1039/d1sc02751d] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/09/2021] [Indexed: 12/14/2022] Open
Abstract
X-ray crystallography is the gold standard to resolve conformational ensembles that are significant for protein function, ligand discovery, and computational methods development. However, relevant conformational states may be missed at common cryogenic (cryo) data-collection temperatures but can be populated at room temperature. To assess the impact of temperature on making structural and computational discoveries, we systematically investigated protein conformational changes in response to temperature and ligand binding in a structural and computational workhorse, the T4 lysozyme L99A cavity. Despite decades of work on this protein, shifting to RT reveals new global and local structural changes. These include uncovering an apo helix conformation that is hidden at cryo but relevant for ligand binding, and altered side chain and ligand conformations. To evaluate the impact of temperature-induced protein and ligand changes on the utility of structural information in computation, we evaluated how temperature can mislead computational methods that employ cryo structures for validation. We find that when comparing simulated structures just to experimental cryo structures, hidden successes and failures often go unnoticed. When using structural information in ligand binding predictions, both coarse docking and rigorous binding free energy calculations are influenced by temperature effects. The trend that cryo artifacts limit the utility of structures for computation holds across five distinct protein classes. Our results suggest caution when consulting cryogenic structural data alone, as temperature artifacts can conceal errors and prevent successful computational predictions, which can mislead the development and application of computational methods in discovering bioactive molecules.
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Affiliation(s)
- Shanshan Y C Bradford
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital Memphis TN 38105 USA
| | - Léa El Khoury
- Department of Pharmaceutical Sciences, University of California Irvine CA 92697 USA
| | - Yunhui Ge
- Department of Pharmaceutical Sciences, University of California Irvine CA 92697 USA
| | - Meghan Osato
- Department of Pharmaceutical Sciences, University of California Irvine CA 92697 USA
| | - David L Mobley
- Department of Pharmaceutical Sciences, University of California Irvine CA 92697 USA
- Department of Chemistry, University of California Irvine CA 92697 USA
| | - Marcus Fischer
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital Memphis TN 38105 USA
- Department of Structural Biology, St. Jude Children's Research Hospital Memphis TN 38105 USA
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8
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Xi K, Hu Z, Wu Q, Wei M, Qian R, Zhu L. Assessing the Performance of Traveling-salesman based Automated Path Searching (TAPS) on Complex Biomolecular Systems. J Chem Theory Comput 2021; 17:5301-5311. [PMID: 34270241 DOI: 10.1021/acs.jctc.1c00182] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Though crucial for understanding the function of large biomolecular systems, locating the minimum free energy paths (MFEPs) between their key conformational states is far from trivial due to their high-dimensional nature. Most existing path-searching methods require a static collective variable space as input, encoding intuition or prior knowledge of the transition mechanism. Such information is, however, hardly available a priori and expensive to validate. To alleviate this issue, we have previously introduced a Traveling-salesman based Automated Path Searching method (TAPS) and demonstrated its efficiency on simple peptide systems. Having implemented a parallel version of this method, here we assess the performance of TAPS on three realistic systems (tens to hundreds of residues) in explicit solvents. We show that TAPS successfully located the MFEP for the ground/excited state transition of the T4 lysozyme L99A variant, consistent with previous findings. TAPS also helped identifying the important role of the two polar contacts in directing the loop-in/loop-out transition of the mitogen-activated protein kinase kinase (MEK1), which explained previous mutant experiments. Remarkably, at a minimal cost of 126 ns sampling, TAPS revealed that the Ltn40/Ltn10 transition of lymphotactin needs no complete unfolding/refolding of its β-sheets and that five polar contacts are sufficient to stabilize the various partially unfolded intermediates along the MFEP. These results present TAPS as a general and promising tool for studying the functional dynamics of complex biomolecular systems.
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Affiliation(s)
- Kun Xi
- Warshel Institute for Computational Biology, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, Guangdong 518172, P. R. China.,School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Zhenquan Hu
- Warshel Institute for Computational Biology, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, Guangdong 518172, P. R. China.,School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Qiang Wu
- School of Science and Engineering, The Chinese University of Hong Kong (Shenzhen), Shenzhen, Guangdong 518172, P. R. China
| | - Meihan Wei
- Warshel Institute for Computational Biology, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, Guangdong 518172, P. R. China
| | - Runtong Qian
- Warshel Institute for Computational Biology, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, Guangdong 518172, P. R. China
| | - Lizhe Zhu
- Warshel Institute for Computational Biology, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, Guangdong 518172, P. R. China
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9
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Abdullin D, Schiemann O. Localization of metal ions in biomolecules by means of pulsed dipolar EPR spectroscopy. Dalton Trans 2021; 50:808-815. [PMID: 33416053 DOI: 10.1039/d0dt03596c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Metal ions are important for the folding, structure, and function of biomolecules. Thus, knowing where their binding sites are located in proteins or oligonucleotides is a critical objective. X-ray crystallography and nuclear magnetic resonance are powerful methods in this respect, but both have their limitations. Here, a complementary method is highlighted in which paramagnetic metal ions are localized by means of trilateration using a combination of site-directed spin labeling and pulsed dipolar electron paramagnetic resonance spectroscopy. The working principle, the requirements, and the limitations of the method are critically discussed. Several applications of the method are outlined and compared with each other.
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Affiliation(s)
- Dinar Abdullin
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany.
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10
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Lai Y, Kuo Y, Chiang Y. Identifying Protein Conformational Dynamics Using Spin‐label ESR. Chem Asian J 2019; 14:3981-3991. [DOI: 10.1002/asia.201900855] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/02/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Yei‐Chen Lai
- Department of Chemistry National Tsing Hua University Hsinchu 30013 Taiwan
- Department of Chemistry&Biochemistry University of California Santa Barbara CA 93106-9510 USA
| | - Yun‐Hsuan Kuo
- Department of Chemistry National Tsing Hua University Hsinchu 30013 Taiwan
| | - Yun‐Wei Chiang
- Department of Chemistry National Tsing Hua University Hsinchu 30013 Taiwan
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11
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Niitsu A, Re S, Oshima H, Kamiya M, Sugita Y. De Novo Prediction of Binders and Nonbinders for T4 Lysozyme by gREST Simulations. J Chem Inf Model 2019; 59:3879-3888. [DOI: 10.1021/acs.jcim.9b00416] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Ai Niitsu
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, Hirosawa 2-1, Wako, Saitama 351-0198, Japan
| | - Suyong Re
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, 6-7-1 Minatojima-minamimachi,
Chuo-ku, Kobe 650-0047, Japan
| | - Hiraku Oshima
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, 6-7-1 Minatojima-minamimachi,
Chuo-ku, Kobe 650-0047, Japan
| | - Motoshi Kamiya
- Computational Biophysics Research Team, RIKEN Center for Computational Science, 6-7-1 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Yuji Sugita
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, Hirosawa 2-1, Wako, Saitama 351-0198, Japan
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, 6-7-1 Minatojima-minamimachi,
Chuo-ku, Kobe 650-0047, Japan
- Computational Biophysics Research Team, RIKEN Center for Computational Science, 6-7-1 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
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12
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Gamble Jarvi A, Cunningham TF, Saxena S. Efficient localization of a native metal ion within a protein by Cu2+-based EPR distance measurements. Phys Chem Chem Phys 2019; 21:10238-10243. [DOI: 10.1039/c8cp07143h] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A native paramagnetic metal binding site in a protein is located with less than 2 Å resolution by a combination of double histidine (dHis) based Cu2+ labeling and long range distance measurements by EPR.
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Affiliation(s)
| | | | - Sunil Saxena
- Department of Chemistry
- University of Pittsburgh
- Pittsburgh
- USA
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13
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Bester SM, Guelta MA, Cheung J, Winemiller MD, Bae SY, Myslinski J, Pegan SD, Height JJ. Structural Insights of Stereospecific Inhibition of Human Acetylcholinesterase by VX and Subsequent Reactivation by HI-6. Chem Res Toxicol 2018; 31:1405-1417. [PMID: 30462502 DOI: 10.1021/acs.chemrestox.8b00294] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Over 50 years ago, the toxicity of irreversible organophosphate inhibitors targeting human acetylcholinesterase (hAChE) was observed to be stereospecific. The therapeutic reversal of hAChE inhibition by reactivators has also been shown to depend on the stereochemistry of the inhibitor. To gain clarity on the mechanism of stereospecific inhibition, the X-ray crystallographic structures of hAChE inhibited by a racemic mixture of VX (P R/S) and its enantiomers were obtained. Beyond identifying hAChE structural features that lend themselves to stereospecific inhibition, structures of the reactivator HI-6 bound to hAChE inhibited by VX enantiomers of varying toxicity, or in its uninhibited state, were obtained. Comparison of hAChE in these pre-reactivation and post-reactivation states along with enzymatic data reveals the potential influence of unproductive reactivator poses on the efficacy of these types of therapeutics. The recognition of structural features related to hAChE's stereospecificity toward VX shed light on the molecular influences of toxicity and their effect on reactivators. In addition to providing a better understanding of the innate issues with current reactivators, an avenue for improvement of reactivators is envisioned.
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Affiliation(s)
- Stephanie M Bester
- Department of Pharmaceutical and Biomedical Sciences , University of Georgia , Athens , Georgia 30602 , United States
| | - Mark A Guelta
- Edgewood Chemical Biological Center, United States Army , Aberdeen Proving Ground, Aberdeen , Maryland 21010 , United States
| | - Jonah Cheung
- New York Structural Biology Center , New York , New York 10027 , United States
| | - Mark D Winemiller
- Edgewood Chemical Biological Center, United States Army , Aberdeen Proving Ground, Aberdeen , Maryland 21010 , United States
| | - Su Y Bae
- Edgewood Chemical Biological Center, United States Army , Aberdeen Proving Ground, Aberdeen , Maryland 21010 , United States
| | - James Myslinski
- Edgewood Chemical Biological Center, United States Army , Aberdeen Proving Ground, Aberdeen , Maryland 21010 , United States
| | - Scott D Pegan
- Department of Pharmaceutical and Biomedical Sciences , University of Georgia , Athens , Georgia 30602 , United States.,Edgewood Chemical Biological Center, United States Army , Aberdeen Proving Ground, Aberdeen , Maryland 21010 , United States
| | - Jude J Height
- Edgewood Chemical Biological Center, United States Army , Aberdeen Proving Ground, Aberdeen , Maryland 21010 , United States
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14
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Allosteric Modulation of Binding Specificity by Alternative Packing of Protein Cores. J Mol Biol 2018; 431:336-350. [PMID: 30471255 DOI: 10.1016/j.jmb.2018.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 11/04/2018] [Accepted: 11/14/2018] [Indexed: 11/21/2022]
Abstract
Hydrophobic cores are often viewed as tightly packed and rigid, but they do show some plasticity and could thus be attractive targets for protein design. Here we explored the role of different functional pressures on the core packing and ligand recognition of the SH3 domain from human Fyn tyrosine kinase. We randomized the hydrophobic core and used phage display to select variants that bound to each of three distinct ligands. The three evolved groups showed remarkable differences in core composition, illustrating the effect of different selective pressures on the core. Changes in the core did not significantly alter protein stability, but were linked closely to changes in binding affinity and specificity. Structural analysis and molecular dynamics simulations revealed the structural basis for altered specificity. The evolved domains had significantly reduced core volumes, which in turn induced increased backbone flexibility. These motions were propagated from the core to the binding surface and induced significant conformational changes. These results show that alternative core packing and consequent allosteric modulation of binding interfaces could be used to engineer proteins with novel functions.
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15
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Edwards TH, Stoll S. Optimal Tikhonov regularization for DEER spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 288:58-68. [PMID: 29414064 PMCID: PMC5840305 DOI: 10.1016/j.jmr.2018.01.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 01/27/2018] [Accepted: 01/29/2018] [Indexed: 05/05/2023]
Abstract
Tikhonov regularization is the most commonly used method for extracting distance distributions from experimental double electron-electron resonance (DEER) spectroscopy data. This method requires the selection of a regularization parameter, α, and a regularization operator, L. We analyze the performance of a large set of α selection methods and several regularization operators, using a test set of over half a million synthetic noisy DEER traces. These are generated from distance distributions obtained from in silico double labeling of a protein crystal structure of T4 lysozyme with the spin label MTSSL. We compare the methods and operators based on their ability to recover the model distance distributions from the noisy time traces. The results indicate that several α selection methods perform quite well, among them the Akaike information criterion and the generalized cross validation method with either the first- or second-derivative operator. They perform significantly better than currently utilized L-curve methods.
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Affiliation(s)
- Thomas H Edwards
- Department of Chemistry, University of Washington, Seattle, WA 98103, United States.
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98103, United States.
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16
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Colloc'h N, Carpentier P, Montemiglio LC, Vallone B, Prangé T. Mapping Hydrophobic Tunnels and Cavities in Neuroglobin with Noble Gas under Pressure. Biophys J 2017; 113:2199-2206. [PMID: 29108649 DOI: 10.1016/j.bpj.2017.10.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/12/2017] [Accepted: 10/06/2017] [Indexed: 01/27/2023] Open
Abstract
Internal cavities are crucial for conformational flexibility of proteins and can be mapped through noble gas diffusion and docking. Here we investigate the hydrophobic cavities and tunnel network in neuroglobin (Ngb), a hexacoordinated heme protein likely to be involved in neuroprotection, using crystallography under noble gas pressure, mostly at room temperature. In murine Ngb, a large internal cavity is involved in the heme sliding mechanism to achieve binding of gaseous ligands through coordination to the heme iron. In this study, we report that noble gases are hosted by two major sites within the internal cavity. We propose that these cavities could store oxygen and allow its relay in the heme proximity, which could correspond to NO location in the nitrite-reductase function of Ngb. Thanks to a recently designed pressurization cell using krypton at high pressure, a new gas binding site has been characterized that reveals an alternate pathway for gaseous ligands. A new gas binding site on the proximal side of the heme has also been characterized, using xenon pressure on a Ngb mutant (V140W) that binds CO with a similar rate and affinity to the wild-type, despite a reshaping of the internal cavity. Moreover, this study, to our knowledge, provides new insights into the determinants of the heme sliding mechanism, suggesting that the shift at the beginning of helix G precedes and drives this process.
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Affiliation(s)
- Nathalie Colloc'h
- ISTCT CNRS UNICAEN CEA Normandie University, CERVOxy Team, Centre Cyceron, Caen, France.
| | - Philippe Carpentier
- CEA/DRF/BIG/CBM/BioCat LCBM CNRS UMR 5249, Université Grenoble Alpes, Grenoble, France; European Synchrotron Radiation Facility, Grenoble, France
| | - Laura C Montemiglio
- Instituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Sapienza Università di Roma, Roma, Italy
| | - Beatrice Vallone
- Instituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Sapienza Università di Roma, Roma, Italy
| | - Thierry Prangé
- LCRB, UMR 8015 CNRS Université Paris Descartes, Paris, France
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17
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Wang Y, Martins JM, Lindorff-Larsen K. Biomolecular conformational changes and ligand binding: from kinetics to thermodynamics. Chem Sci 2017; 8:6466-6473. [PMID: 29619200 PMCID: PMC5859887 DOI: 10.1039/c7sc01627a] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 07/10/2017] [Indexed: 12/15/2022] Open
Abstract
The behaviour of biomolecular systems is governed by their thermodynamic and kinetic properties. It is thus important to be able to calculate, for example, both the affinity and rate of binding and dissociation of a protein-ligand complex, or the populations and exchange rates between distinct conformational states. Because these are typically rare events, calculating these properties from long molecular dynamics simulations remains extremely difficult. Instead, one often adopts a divide-and-conquer strategy in which equilibrium free-energy differences and the fastest state-to-state transition (e.g. ligand association or minor-to-major state conversion) are combined to estimate the slow rate (e.g. ligand dissociation) using a two-state assumption. Here we instead address these problems by using a previously developed method to calculate both the forward and backward rates directly from simulations. We then estimate the thermodynamics from the rates, and validate these values by independent means. We applied the approach to three systems of increasing complexity, including the association and dissociation of benzene to a fully buried cavity inside the L99A mutant variant of T4 lysozyme. In particular, we were able to determine both millisecond association and dissociation rates, and the affinity, of the protein-ligand system by directly observing dozens of rare events in atomic detail. Our approach both sheds light on the precision of methods for calculating kinetics and further provides a generally useful test for the internal consistency of kinetics and thermodynamics. We also expect our route to be useful for obtaining both the kinetics and thermodynamics at the same time in more challenging cases.
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Affiliation(s)
- Yong Wang
- Structural Biology and NMR Laboratory , Linderstrøm-Lang Centre for Protein Science , Department of Biology , University of Copenhagen , Ole Maaløes Vej 5 , DK-2200 Copenhagen N , Denmark .
| | - João Miguel Martins
- Structural Biology and NMR Laboratory , Linderstrøm-Lang Centre for Protein Science , Department of Biology , University of Copenhagen , Ole Maaløes Vej 5 , DK-2200 Copenhagen N , Denmark .
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory , Linderstrøm-Lang Centre for Protein Science , Department of Biology , University of Copenhagen , Ole Maaløes Vej 5 , DK-2200 Copenhagen N , Denmark .
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18
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Colloc'h N, Sacquin-Mora S, Avella G, Dhaussy AC, Prangé T, Vallone B, Girard E. Determinants of neuroglobin plasticity highlighted by joint coarse-grained simulations and high pressure crystallography. Sci Rep 2017; 7:1858. [PMID: 28500341 PMCID: PMC5431840 DOI: 10.1038/s41598-017-02097-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/20/2017] [Indexed: 11/09/2022] Open
Abstract
Investigating the effect of pressure sheds light on the dynamics and plasticity of proteins, intrinsically correlated to functional efficiency. Here we detail the structural response to pressure of neuroglobin (Ngb), a hexacoordinate globin likely to be involved in neuroprotection. In murine Ngb, reversible coordination is achieved by repositioning the heme more deeply into a large internal cavity, the “heme sliding mechanism”. Combining high pressure crystallography and coarse-grain simulations on wild type Ngb as well as two mutants, one (V101F) with unaffected and another (F106W) with decreased affinity for CO, we show that Ngb hinges around a rigid mechanical nucleus of five hydrophobic residues (V68, I72, V109, L113, Y137) during its conformational transition induced by gaseous ligand, that the intrinsic flexibility of the F-G loop appears essential to drive the heme sliding mechanism, and that residue Val 101 may act as a sensor of the interaction disruption between the heme and the distal histidine.
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Affiliation(s)
- Nathalie Colloc'h
- ISTCT CNRS UNICAEN CEA Normandie Univ., CERVOxy team, centre Cyceron, 14000, Caen, France.
| | - Sophie Sacquin-Mora
- Laboratoire de Biochimie Théorique, CNRS UPR9080, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - Giovanna Avella
- Instituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, 5 piazzale Aldo Moro, 00185, Roma, Italy.,BIOGEM Research Institute, Ariano Irpino, Italy
| | - Anne-Claire Dhaussy
- CRISTMAT UMR 6508 CNRS ENSICAEN UNICAEN Normandie Univ., 6 bd du Maréchal Juin, 14050, Caen, France
| | - Thierry Prangé
- LCRB, UMR 8015 CNRS Université Paris Descartes, 4 avenue de l'Observatoire, 75270, Paris, France
| | - Beatrice Vallone
- Instituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, 5 piazzale Aldo Moro, 00185, Roma, Italy
| | - Eric Girard
- Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, 38044, Grenoble, France.
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19
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Pan Y, Neupane S, Farmakes J, Bridges M, Froberg J, Rao J, Qian SY, Liu G, Choi Y, Yang Z. Probing the structural basis and adsorption mechanism of an enzyme on nano-sized protein carriers. NANOSCALE 2017; 9:3512-3523. [PMID: 28244542 DOI: 10.1039/c7nr00276a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Silica nanoparticles (SiNPs) are important nano-sized, solid-state carriers/hosts to load, store, and deliver biological or pharmaceutical cargoes. They are also good potential solid supports to immobilize proteins for fundamental protein structure and dynamics studies. However, precaution is necessary when using SiNPs in these areas because adsorption might alter the activity of the cargoes, especially when enzymes are loaded. Therefore, it becomes important to understand the structural basis of the cargo enzyme activity changes, if there is any. The high complexity and dynamics of the nano-bio interface present many challenges. Reported here is a comprehensive study of the structure, dynamics, and activity of a model enzyme, T4 lysozyme, upon adsorption to a few surface-modified SiNPs using several experimental techniques. Not surprisingly, a significant activity loss on each studied SiNP was found. The structural basis of the activity loss was identified based on results from a unique technique, the Electron Paramagnetic Resonance (EPR) spectroscopy, which probes structural information regardless of the complexity. Several docking models of the enzyme on SiNPs with different surfaces, at different enzyme-to-SiNP ratios are proposed. Interestingly, we found that the adsorbed enzyme can be desorbed via pH adjustment, which highlighted the potential to use SiNPs for enzyme/protein delivery or storage due to the high capacity. In order to use SiNPs as enzyme hosts, minimizing the enzymatic activity loss upon adsorption is needed. Lastly, the work outlined here demonstrate the use of EPR in probing structural information on the complex (inorganic)nano-bio interface.
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Affiliation(s)
- Yanxiong Pan
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Sunanda Neupane
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Jasmin Farmakes
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Michael Bridges
- Jules Stein Eye Institute, University of California, Los Angeles, CA 90025, USA
| | - James Froberg
- Department of Physics, North Dakota State University, Fargo, ND 58108, USA
| | - Jiajia Rao
- Department of Plant Sciences, North Dakota State University, Fargo, ND 58108, USA
| | - Steven Y Qian
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58108, USA
| | - Guodong Liu
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Yongki Choi
- Department of Physics, North Dakota State University, Fargo, ND 58108, USA
| | - Zhongyu Yang
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
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20
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Consentius P, Gohlke U, Loll B, Alings C, Müller R, Heinemann U, Kaupp M, Wahl M, Risse T. Tracking Transient Conformational States of T4 Lysozyme at Room Temperature Combining X-ray Crystallography and Site-Directed Spin Labeling. J Am Chem Soc 2016; 138:12868-12875. [DOI: 10.1021/jacs.6b05507] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Philipp Consentius
- Institute
of Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Ulrich Gohlke
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Bernhard Loll
- Institute
of Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Claudia Alings
- Institute
of Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Robert Müller
- Institute
of Chemistry, Sekr. C7, Technische Universität Berlin, Straße des
17. Juni 135, 10623 Berlin, Germany
| | - Udo Heinemann
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Str. 10, 13125 Berlin, Germany
- Institute
of Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Martin Kaupp
- Institute
of Chemistry, Sekr. C7, Technische Universität Berlin, Straße des
17. Juni 135, 10623 Berlin, Germany
| | - Markus Wahl
- Institute
of Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Thomas Risse
- Institute
of Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
- Berlin
Joint EPR Laboratory, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
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21
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Edwards TH, Stoll S. A Bayesian approach to quantifying uncertainty from experimental noise in DEER spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 270:87-97. [PMID: 27414762 PMCID: PMC4996738 DOI: 10.1016/j.jmr.2016.06.021] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 06/29/2016] [Accepted: 06/30/2016] [Indexed: 05/05/2023]
Abstract
Double Electron-Electron Resonance (DEER) spectroscopy is a solid-state pulse Electron Paramagnetic Resonance (EPR) experiment that measures distances between unpaired electrons, most commonly between protein-bound spin labels separated by 1.5-8nm. From the experimental data, a distance distribution P(r) is extracted using Tikhonov regularization. The disadvantage of this method is that it does not directly provide error bars for the resulting P(r), rendering correct interpretation difficult. Here we introduce a Bayesian statistical approach that quantifies uncertainty in P(r) arising from noise and numerical regularization. This method provides credible intervals (error bars) of P(r) at each r. This allows practitioners to answer whether or not small features are significant, whether or not apparent shoulders are significant, and whether or not two distance distributions are significantly different from each other. In addition, the method quantifies uncertainty in the regularization parameter.
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Affiliation(s)
- Thomas H Edwards
- Department of Chemistry, University of Washington, Seattle, WA 98103, United States.
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98103, United States.
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22
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Wang Y, Papaleo E, Lindorff-Larsen K. Mapping transiently formed and sparsely populated conformations on a complex energy landscape. eLife 2016; 5. [PMID: 27552057 PMCID: PMC5050026 DOI: 10.7554/elife.17505] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/22/2016] [Indexed: 12/11/2022] Open
Abstract
Determining the structures, kinetics, thermodynamics and mechanisms that underlie conformational exchange processes in proteins remains extremely difficult. Only in favourable cases is it possible to provide atomic-level descriptions of sparsely populated and transiently formed alternative conformations. Here we benchmark the ability of enhanced-sampling molecular dynamics simulations to determine the free energy landscape of the L99A cavity mutant of T4 lysozyme. We find that the simulations capture key properties previously measured by NMR relaxation dispersion methods including the structure of a minor conformation, the kinetics and thermodynamics of conformational exchange, and the effect of mutations. We discover a new tunnel that involves the transient exposure towards the solvent of an internal cavity, and show it to be relevant for ligand escape. Together, our results provide a comprehensive view of the structural landscape of a protein, and point forward to studies of conformational exchange in systems that are less characterized experimentally. DOI:http://dx.doi.org/10.7554/eLife.17505.001 Proteins are the workhorses of cells, where they perform a wide range of roles. To do so, they adopt specific three-dimensional structures that enable them to interact with other molecules as necessary. Often a protein needs to be able to shift between different states with distinct structures as it goes about its job. To fully understand how a protein works, it is important to be able to characterize these different structures and how the protein changes between them. Many of the experimental techniques used to study protein structure rely on isolating the individual structural forms of a protein. Since many structures only exist briefly, this can be very difficult. To complement experimental results, computer simulations allow researchers to model how atoms behave within a molecule. However, a number of factors limit how well these models represent what happens experimentally, such as the accuracy of the physical description used for the modeling. Wang et al. set out to test and benchmark how well computer simulations could model changes in structure for a protein called T4 lysozyme, which has been studied extensively using experimental techniques. T4 lysozyme exists in two different states that have distinct structures. By comparing existing detailed experimental measurements with the results of their simulations, Wang et al. found that the simulations could capture key aspects of how T4 lysozyme changes its shape. The simulations described the structure of the protein in both states and accurately determined the relative proportion of molecules that are found in each state. They could also determine how long it takes for a molecule to change its shape from one state to the other. The findings allowed Wang et al. to describe in fine detail – down to the level of individual atoms – how the protein changes its shape and how mutations in the protein affect its ability to do so. A key question for future studies is whether these insights can be extended to other proteins that are less well characterized experimentally than T4 lysozyme. DOI:http://dx.doi.org/10.7554/eLife.17505.002
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Affiliation(s)
- Yong Wang
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Elena Papaleo
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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23
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Kerzhner M, Abdullin D, Więcek J, Matsuoka H, Hagelueken G, Schiemann O, Famulok M. Post-synthetic Spin-Labeling of RNA through Click Chemistry for PELDOR Measurements. Chemistry 2016; 22:12113-21. [PMID: 27412453 DOI: 10.1002/chem.201601897] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 01/24/2023]
Abstract
Site-directed spin labeling of RNA based on click chemistry is used in combination with pulsed electron-electron double resonance (PELDOR) to benchmark a nitroxide spin label, called here dŲ. We compare this approach with another established method that employs the rigid spin label Çm for RNA labeling. By using CD spectroscopy, thermal denaturation measurements, CW-EPR as well as PELDOR we analyzed and compared the influence of dŲ and Çm on a self-complementary RNA duplex. Our results demonstrate that the conformational diversity of dŲ is significantly reduced near the freezing temperature of a phosphate buffer, resulting in strongly orientation-selective PELDOR time traces of the dŲ-labeled RNA duplex.
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Affiliation(s)
- Mark Kerzhner
- Life & Medical Sciences Institute, Chemical Biology & Medicinal Chemistry Unit c/o Kekulé-Institut für Organische Chemie und Biochemie, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Dinar Abdullin
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Jennifer Więcek
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Hideto Matsuoka
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Gregor Hagelueken
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Olav Schiemann
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany.
| | - Michael Famulok
- Life & Medical Sciences Institute, Chemical Biology & Medicinal Chemistry Unit c/o Kekulé-Institut für Organische Chemie und Biochemie, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany. .,Max-Planck Fellow Group Chemical Biology, Center of Advanced European Studies and Research, Ludwig-Erhard-Allee 2, 53175, Bonn, Germany.
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24
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Wei G, Xi W, Nussinov R, Ma B. Protein Ensembles: How Does Nature Harness Thermodynamic Fluctuations for Life? The Diverse Functional Roles of Conformational Ensembles in the Cell. Chem Rev 2016; 116:6516-51. [PMID: 26807783 PMCID: PMC6407618 DOI: 10.1021/acs.chemrev.5b00562] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
All soluble proteins populate conformational ensembles that together constitute the native state. Their fluctuations in water are intrinsic thermodynamic phenomena, and the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are optimized to perform their biological functions. In this review we briefly describe advances in free energy landscape studies of protein conformational ensembles. Experimental (nuclear magnetic resonance, small-angle X-ray scattering, single-molecule spectroscopy, and cryo-electron microscopy) and computational (replica-exchange molecular dynamics, metadynamics, and Markov state models) approaches have made great progress in recent years. These address the challenging characterization of the highly flexible and heterogeneous protein ensembles. We focus on structural aspects of protein conformational distributions, from collective motions of single- and multi-domain proteins, intrinsically disordered proteins, to multiprotein complexes. Importantly, we highlight recent studies that illustrate functional adjustment of protein conformational ensembles in the crowded cellular environment. We center on the role of the ensemble in recognition of small- and macro-molecules (protein and RNA/DNA) and emphasize emerging concepts of protein dynamics in enzyme catalysis. Overall, protein ensembles link fundamental physicochemical principles and protein behavior and the cellular network and its regulation.
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Affiliation(s)
- Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Wenhui Xi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
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25
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Mei Y, Ramanathan A, Glover K, Stanley C, Sanishvili R, Chakravarthy S, Yang Z, Colbert CL, Sinha SC. Conformational Flexibility Enables the Function of a BECN1 Region Essential for Starvation-Mediated Autophagy. Biochemistry 2016; 55:1945-58. [PMID: 26937551 DOI: 10.1021/acs.biochem.5b01264] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BECN1 is essential for autophagy, a critical eukaryotic cellular homeostasis pathway. Here we delineate a highly conserved BECN1 domain located between previously characterized BH3 and coiled-coil domains and elucidate its structure and role in autophagy. The 2.0 Å sulfur-single-wavelength anomalous dispersion X-ray crystal structure of this domain demonstrates that its N-terminal half is unstructured while its C-terminal half is helical; hence, we name it the flexible helical domain (FHD). Circular dichroism spectroscopy, double electron-electron resonance-electron paramagnetic resonance, and small-angle X-ray scattering (SAXS) analyses confirm that the FHD is partially disordered, even in the context of adjacent BECN1 domains. Molecular dynamic simulations fitted to SAXS data indicate that the FHD transiently samples more helical conformations. FHD helicity increases in 2,2,2-trifluoroethanol, suggesting it may become more helical upon binding. Lastly, cellular studies show that conserved FHD residues are required for starvation-induced autophagy. Thus, the FHD likely undergoes a binding-associated disorder-to-helix transition, and conserved residues critical for this interaction are essential for starvation-induced autophagy.
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Affiliation(s)
- Yang Mei
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58108-6050, United States
| | - Arvind Ramanathan
- Health Data Sciences Institute, Computational Science and Engineering Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37830, United States
| | - Karen Glover
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58108-6050, United States
| | - Christopher Stanley
- Biology and Soft Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Ruslan Sanishvili
- GMCA@APS, X-ray Science Division, Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Srinivas Chakravarthy
- Bio-CAT, Advanced Photon Source , 9700 South Cass Avenue, Building 435B, Argonne, Illinois 60439, United States
| | - Zhongyu Yang
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58108-6050, United States
| | - Christopher L Colbert
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58108-6050, United States
| | - Sangita C Sinha
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58108-6050, United States
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26
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Stadtmueller BM, Huey-Tubman KE, López CJ, Yang Z, Hubbell WL, Bjorkman PJ. The structure and dynamics of secretory component and its interactions with polymeric immunoglobulins. eLife 2016; 5. [PMID: 26943617 PMCID: PMC4786434 DOI: 10.7554/elife.10640] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 01/21/2016] [Indexed: 02/06/2023] Open
Abstract
As a first-line vertebrate immune defense, the polymeric immunoglobulin receptor (pIgR) transports polymeric IgA and IgM across epithelia to mucosal secretions, where the cleaved ectodomain (secretory component; SC) becomes a component of secretory antibodies, or when unliganded, binds and excludes bacteria. Here we report the 2.6Å crystal structure of unliganded human SC (hSC) and comparisons with a 1.7Å structure of teleost fish SC (tSC), an early pIgR ancestor. The hSC structure comprises five immunoglobulin-like domains (D1-D5) arranged as a triangle, with an interface between ligand-binding domains D1 and D5. Electron paramagnetic resonance measurements confirmed the D1-D5 interface in solution and revealed that it breaks upon ligand binding. Together with binding studies of mutant and chimeric SCs, which revealed domain contributions to secretory antibody formation, these results provide detailed models for SC structure, address pIgR evolution, and demonstrate that SC uses multiple conformations to protect mammals from pathogens. DOI:http://dx.doi.org/10.7554/eLife.10640.001 A sticky substance called mucus lines our airways and gut, where it acts as a physical barrier to prevent bacteria and other microbes from entering the body. Mucus also contains proteins called antibodies that can bind to and neutralize molecules from microbes (known as antigens). The primary antibody found in mucus is called Immunoglobulin A. This antibody is produced by immune cells within the body and must pass through the “epithelial” cells that line the airway or gut to reach the layer of mucus. These epithelial cells have a receptor protein called the polymeric immunoglobulin receptor (plgR) that binds to Immunoglobulin A molecules, transports them across the cell, and then releases them into the mucus layer. The pIgR also releases Immunoglobulin A into breast milk, which protects nursing infants until their own immune system has developed. When released into the mucus layer, the Immunoglobulin A antibodies remain attached to a portion of pIgR known as the secretory component. This part of the receptor serves to stabilize and protect the antibodies from being degraded and helps the antibodies to bind to other host and bacterial proteins. Researchers have noted that the secretory component can be released into the mucus even when it is not attached to an antibody. These “free” secretory components have been shown to help prevent bacteria and the toxins they produce from entering the body. Despite the importance of secretory component in immune responses, the three-dimensional structure of the secretory component and how it interacts with antibodies and bacteria remained unknown. Here, Stadtmueller et al. use a technique called X-ray crystallography to determine a three-dimensional model of the free form of a secretory component from humans, and compare it to an ancestral secretory component protein found in fish. Further experiments on the human protein revealed how the structure of the secretory component changes when antibodies bind to it. Stadtmueller et al. propose a model for how both forms of the secretory component can protect the body from microbes and other external agents. The next challenge is to develop a three-dimensional model of the secretory component when it is bound to Immunoglobulin A. DOI:http://dx.doi.org/10.7554/eLife.10640.002
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Affiliation(s)
- Beth M Stadtmueller
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Kathryn E Huey-Tubman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Carlos J López
- Jules Stein Eye Institute, University of California, Los Angeles, United States.,Department of Chemistry and Biochemistry, University of California, Los Angeles, United States
| | - Zhongyu Yang
- Jules Stein Eye Institute, University of California, Los Angeles, United States.,Department of Chemistry and Biochemistry, University of California, Los Angeles, United States
| | - Wayne L Hubbell
- Jules Stein Eye Institute, University of California, Los Angeles, United States.,Department of Chemistry and Biochemistry, University of California, Los Angeles, United States
| | - Pamela J Bjorkman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
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27
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Aitha M, Moller AJ, Sahu ID, Horitani M, Tierney DL, Crowder MW. Investigating the position of the hairpin loop in New Delhi metallo-β-lactamase, NDM-1, during catalysis and inhibitor binding. J Inorg Biochem 2016; 156:35-9. [PMID: 26717260 PMCID: PMC4843777 DOI: 10.1016/j.jinorgbio.2015.10.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/07/2015] [Accepted: 10/19/2015] [Indexed: 12/29/2022]
Abstract
In an effort to examine the relative position of a hairpin loop in New Delhi metallo-β-lactamase, NDM-1, during catalysis, rapid freeze quench double electron electron resonance (RFQ-DEER) spectroscopy was used. A doubly-labeled mutant of NDM-1, which had one spin label on the invariant loop at position 69 and another label at position 235, was prepared and characterized. The reaction of the doubly spin labeled mutant with chromacef was freeze quenched at 500μs and 10ms. DEER results showed that the average distance between labels decreased by 4Å in the 500μs quenched sample and by 2Å in the 10ms quenched sample, as compared to the distance in the unreacted enzyme, although the peaks corresponding to distance distributions were very broad. DEER spectra with the doubly spin labeled enzyme with two inhibitors showed that the distance between the loop residue at position 69 and the spin label at position 235 does not change upon inhibitor binding. This study suggests that the hairpin loop in NDM-1 moves over the metal ion during the catalysis and then moves back to its original position after hydrolysis, which is consistent with a previous hypothesis based on NMR solution studies on a related metallo-β-lactamase. This study also demonstrates that this loop motion occurs in the millisecond time domain.
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Affiliation(s)
- Mahesh Aitha
- Department of Chemistry and Biochemistry, Miami University, 650 East High Street, Oxford, OH 45056, USA
| | - Abraham J Moller
- Department of Chemistry and Biochemistry, Miami University, 650 East High Street, Oxford, OH 45056, USA
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, 650 East High Street, Oxford, OH 45056, USA
| | - Masaki Horitani
- Department of Chemistry, Northwestern University, Evanston, IL 60208-3113, USA
| | - David L Tierney
- Department of Chemistry and Biochemistry, Miami University, 650 East High Street, Oxford, OH 45056, USA
| | - Michael W Crowder
- Department of Chemistry and Biochemistry, Miami University, 650 East High Street, Oxford, OH 45056, USA.
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28
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Zhang C, Wang Y, Sun H, Ren H. Multiple-site mutations of phage Bp7 endolysin improves its activities against target bacteria. Virol Sin 2015; 30:386-95. [PMID: 26490045 DOI: 10.1007/s12250-015-3618-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/02/2015] [Indexed: 11/30/2022] Open
Abstract
The widespread use of antibiotics has caused serious drug resistance. Bacteria that were once easily treatable are now extremely difficult to treat. Endolysin can be used as an alternative to antibiotics for the treatment of drug-resistant bacteria. To analyze the antibacterial activity of the endolysin of phage Bp7 (Bp7e), a 489-bp DNA fragment of endolysin Bp7e was PCR-amplified from a phage Bp7 genome and cloned, and then a pET28a-Bp7e prokaryotic expression vector was constructed. Two amino acids were mutated (L99A, M102E) to construct pET28a-Bp7Δe, with pET28a-Bp7e as a template. Phylogenetic analysis suggested that BP7e belongs to a T4-like phage endolysin group. Bp7e and its mutant Bp7Δe were expressed in Escherichia coli BL21(DE3) as soluble proteins. They were purified by affinity chromatography, and then their antibacterial activities were analyzed. The results demonstrated that the recombinant proteins Bp7e and Bp7Δe showed obvious antibacterial activity against Micrococcus lysodeikticus but no activity against Staphylococcus aureus. In the presence of malic acid, Bp7e and Bp7Δe exhibited an effect on most E. coli strains which could be lysed by phage Bp7, but no effect on Salmonella paratyphi or Pseudomonas aeruginosa. Moreover, Bp7Δe with double-site mutations showed stronger antibacterial activity and a broader lysis range than Bp7e.
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Affiliation(s)
- Can Zhang
- College of Animal Husbandry and Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Yuanchao Wang
- College of Animal Husbandry and Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Huzhi Sun
- College of Animal Husbandry and Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Huiying Ren
- College of Animal Husbandry and Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
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29
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High-Pressure EPR and Site-Directed Spin Labeling for Mapping Molecular Flexibility in Proteins. Methods Enzymol 2015; 564:29-57. [PMID: 26477247 DOI: 10.1016/bs.mie.2015.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
High hydrostatic pressure is a powerful probe of protein conformational flexibility. Pressurization reveals regions of elevated compressibility, and thus flexibility, within individual conformational states, but also shifts conformational equilibria such that "invisible" excited states become accessible for spectroscopic characterization. The central aim of this chapter is to describe recently developed instrumentation and methodologies that enable high-pressure site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) experiments on proteins and to demonstrate the information content of these experiments by highlighting specific recent applications. A brief introduction to the thermodynamics of proteins under pressure is presented first, followed by a discussion of the principles underlying SDSL-EPR detection of pressure effects in proteins, and the suitability of SDSL-EPR for this purpose in terms of timescale and ability to characterize conformational heterogeneity. Instrumentation and practical considerations for variable-pressure continuous wave EPR and pressure-resolved double electron-electron resonance (PR DEER) experiments are reviewed, and finally illustrations of data analysis using recent applications are presented. Although high-pressure SDSL-EPR is in its infancy, the recent applications presented highlight the considerable potential of the method to (1) identify compressible (flexible) regions in a folded protein; (2) determine thermodynamic parameters that relate conformational states in equilibrium; (3) populate and characterize excited states of proteins undetected at atmospheric pressure; (4) reveal the structural heterogeneity of conformational ensembles and provide distance constraints on the global structure of pressure-populated states with PR DEER.
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30
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Maeno A, Sindhikara D, Hirata F, Otten R, Dahlquist FW, Yokoyama S, Akasaka K, Mulder FAA, Kitahara R. Cavity as a source of conformational fluctuation and high-energy state: high-pressure NMR study of a cavity-enlarged mutant of T4 lysozyme. Biophys J 2015; 108:133-45. [PMID: 25564860 DOI: 10.1016/j.bpj.2014.11.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 11/02/2014] [Accepted: 11/07/2014] [Indexed: 10/24/2022] Open
Abstract
Although the structure, function, conformational dynamics, and controlled thermodynamics of proteins are manifested by their corresponding amino acid sequences, the natural rules for molecular design and their corresponding interplay remain obscure. In this study, we focused on the role of internal cavities of proteins in conformational dynamics. We investigated the pressure-induced responses from the cavity-enlarged L99A mutant of T4 lysozyme, using high-pressure NMR spectroscopy. The signal intensities of the methyl groups in the (1)H/(13)C heteronuclear single quantum correlation spectra, particularly those around the enlarged cavity, decreased with the increasing pressure, and disappeared at 200 MPa, without the appearance of new resonances, thus indicating the presence of heterogeneous conformations around the cavity within the ground state ensemble. Above 200 MPa, the signal intensities of >20 methyl groups gradually decreased with the increasing pressure, without the appearance of new resonances. Interestingly, these residues closely matched those sensing a large conformational change between the ground- and high-energy states, at atmospheric pressure. (13)C and (1)H NMR line-shape simulations showed that the pressure-induced loss in the peak intensity could be explained by the increase in the high-energy state population. In this high-energy state, the aromatic side chain of F114 gets flipped into the enlarged cavity. The accommodation of the phenylalanine ring into the efficiently packed cavity may decrease the partial molar volume of the high-energy state, relative to the ground state. We suggest that the enlarged cavity is involved in the conformational transition to high-energy states and in the volume fluctuation of the ground state.
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Affiliation(s)
- Akihiro Maeno
- High Pressure Protein Research Center, Institute of Advanced Technology, Kinki University, Kinokawa, Wakayama, Japan; RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Daniel Sindhikara
- College of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Fumio Hirata
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Renee Otten
- Department of Biochemistry, Brandeis University, Waltham, Massachusetts
| | - Frederick W Dahlquist
- Department of Chemistry and Biochemistry and Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara California
| | - Shigeyuki Yokoyama
- RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama, Japan; Department of Biophysics and Biochemistry and Laboratory of Structural Biology, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kazuyuki Akasaka
- High Pressure Protein Research Center, Institute of Advanced Technology, Kinki University, Kinokawa, Wakayama, Japan; RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Frans A A Mulder
- Department of Chemistry and Interdisciplinary Nanoscience Center iNANO, University of Aarhus, Aarhus C, Denmark
| | - Ryo Kitahara
- RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan; College of Pharmaceutical Sciences, Ritsumeikan University, Shiga, Japan.
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31
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Altenbach C, López CJ, Hideg K, Hubbell WL. Exploring Structure, Dynamics, and Topology of Nitroxide Spin-Labeled Proteins Using Continuous-Wave Electron Paramagnetic Resonance Spectroscopy. Methods Enzymol 2015; 564:59-100. [PMID: 26477248 DOI: 10.1016/bs.mie.2015.08.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Structural and dynamical characterization of proteins is of central importance in understanding the mechanisms underlying their biological functions. Site-directed spin labeling (SDSL) combined with continuous-wave electron paramagnetic resonance (CW EPR) spectroscopy has shown the capability of providing this information with site-specific resolution under physiological conditions for proteins of any degree of complexity, including those associated with membranes. This chapter introduces methods commonly employed for SDSL and describes selected CW EPR-based methods that can be applied to (1) map secondary and tertiary protein structure, (2) determine membrane protein topology, (3) measure protein backbone flexibility, and (4) reveal the existence of conformational exchange at equilibrium.
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Affiliation(s)
- Christian Altenbach
- Department of Chemistry and Biochemistry, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Carlos J López
- Department of Chemistry and Biochemistry, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Kálmán Hideg
- Institute of Organic and Medicinal Chemistry, University of Pécs, Pécs, Hungary
| | - Wayne L Hubbell
- Department of Chemistry and Biochemistry, Jules Stein Eye Institute, University of California, Los Angeles, California, USA.
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32
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Sung TC, Li CY, Lai YC, Hung CL, Shih O, Yeh YQ, Jeng US, Chiang YW. Solution Structure of Apoptotic BAX Oligomer: Oligomerization Likely Precedes Membrane Insertion. Structure 2015; 23:1878-1888. [PMID: 26299946 DOI: 10.1016/j.str.2015.07.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 07/06/2015] [Accepted: 07/28/2015] [Indexed: 12/23/2022]
Abstract
Proapoptotic BAX protein is largely cytosolic in healthy cells, but it oligomerizes and translocates to mitochondria upon receiving apoptotic stimuli. A long-standing challenge has been the inability to capture any structural information beyond the onset of activation. Here, we present solution structures of an activated BAX oligomer by means of spectroscopic and scattering methods, providing details about the monomer-monomer interfaces in the oligomer and how the oligomer is assembled from homodimers. We show that this soluble oligomer undergoes a direct conversion into membrane-inserted oligomer, which has the ability of inducing apoptosis and structurally resembles a membrane-embedded oligomer formed from BAX monomers in lipid environment. Structural differences between the soluble and the membrane-inserted oligomers are manifested in the C-terminal helices. Our data suggest an alternative pathway of apoptosis in which BAX oligomer formation occurs prior to membrane insertion.
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Affiliation(s)
- Tai-Ching Sung
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Ching-Yu Li
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yei-Chen Lai
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chien-Lun Hung
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Orion Shih
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yi-Qi Yeh
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - U-Ser Jeng
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
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33
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Guzzi R, Bartucci R. Electron spin resonance of spin-labeled lipid assemblies and proteins. Arch Biochem Biophys 2015; 580:102-11. [PMID: 26116378 DOI: 10.1016/j.abb.2015.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/18/2015] [Accepted: 06/22/2015] [Indexed: 01/29/2023]
Abstract
Spin-label electron spin resonance (ESR) spectroscopy is a valuable means to study molecular mobility and interactions in biological systems. This paper deals with conventional, continuous wave ESR of nitroxide spin-labels at 9-GHz providing an introduction to the basic principles of the technique and applications to self-assembled lipid aggregates and proteins. Emphasis is given to segmental lipid chain order and rotational dynamics of lipid structures, environmental polarity of membranes and proteins, structure and conformational dynamics of proteins.
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Affiliation(s)
- Rita Guzzi
- Department of Physics, University of Calabria, 87036 Rende (CS), Italy
| | - Rosa Bartucci
- Department of Physics, University of Calabria, 87036 Rende (CS), Italy.
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34
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Structure-relaxation mechanism for the response of T4 lysozyme cavity mutants to hydrostatic pressure. Proc Natl Acad Sci U S A 2015; 112:E2437-46. [PMID: 25918400 DOI: 10.1073/pnas.1506505112] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Application of hydrostatic pressure shifts protein conformational equilibria in a direction to reduce the volume of the system. A current view is that the volume reduction is dominated by elimination of voids or cavities in the protein interior via cavity hydration, although an alternative mechanism wherein cavities are filled with protein side chains resulting from a structure relaxation has been suggested [López CJ, Yang Z, Altenbach C, Hubbell WL (2013) Proc Natl Acad Sci USA 110(46):E4306-E4315]. In the present study, mechanisms for elimination of cavities under high pressure are investigated in the L99A cavity mutant of T4 lysozyme and derivatives thereof using site-directed spin labeling, pressure-resolved double electron-electron resonance, and high-pressure circular dichroism spectroscopy. In the L99A mutant, the ground state is in equilibrium with an excited state of only ∼ 3% of the population in which the cavity is filled by a protein side chain [Bouvignies et al. (2011) Nature 477(7362):111-114]. The results of the present study show that in L99A the native ground state is the dominant conformation to pressures of 3 kbar, with cavity hydration apparently taking place in the range of 2-3 kbar. However, in the presence of additional mutations that lower the free energy of the excited state, pressure strongly populates the excited state, thereby eliminating the cavity with a native side chain rather than solvent. Thus, both cavity hydration and structure relaxation are mechanisms for cavity elimination under pressure, and which is dominant is determined by details of the energy landscape.
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35
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36
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Abdullin D, Florin N, Hagelueken G, Schiemann O. EPR-based approach for the localization of paramagnetic metal ions in biomolecules. Angew Chem Int Ed Engl 2014; 54:1827-31. [PMID: 25522037 DOI: 10.1002/anie.201410396] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Indexed: 11/10/2022]
Abstract
Metal ions play an important role in the catalysis and folding of proteins and oligonucleotides. Their localization within the three-dimensional fold of such biomolecules is therefore an important goal in understanding structure-function relationships. A trilateration approach for the localization of metal ions by means of long-range distance measurements based on electron paramagnetic resonance (EPR) is introduced. The approach is tested on the Cu(2+) center of azurin, and factors affecting the precision of the method are discussed.
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Affiliation(s)
- Dinar Abdullin
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstrasse 12, 53115 Bonn (Germany) http://www.schiemann.uni-bonn.de
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37
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Abdullin D, Florin N, Hagelueken G, Schiemann O. EPR-Based Approach for the Localization of Paramagnetic Metal Ions in Biomolecules. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201410396] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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38
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López CJ, Fleissner MR, Brooks EK, Hubbell WL. Stationary-phase EPR for exploring protein structure, conformation, and dynamics in spin-labeled proteins. Biochemistry 2014; 53:7067-75. [PMID: 25333901 PMCID: PMC4238802 DOI: 10.1021/bi5011128] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
![]()
Proteins tethered to solid supports
are of increasing interest
in bioanalytical chemistry and protein science in general. However,
the extent to which tethering modifies the energy landscape and dynamics
of the protein is most often unknown because there are few biophysical
methods that can determine secondary and tertiary structures and explore
conformational equilibria and dynamics of a tethered protein with
site-specific resolution. Site-directed spin labeling (SDSL) combined
with electron paramagnetic resonance (EPR) offers a unique opportunity
for this purpose. Here, we employ a general strategy using unnatural
amino acids that enables efficient and site-specific tethering of
a spin-labeled protein to a Sepharose solid support. Remarkably, EPR
spectra of spin-labeled T4 lysozyme (T4L) reveal that a single site-specific
attachment suppresses rotational motion of the protein sufficiently
to allow interpretation of the spectral line shape in terms of protein
internal dynamics. Importantly, line shape analysis and distance mapping
using double electron–electron resonance reveal that internal
dynamics, the tertiary fold, conformational equilibria, and ligand
binding of the tethered proteins were similar to those in solution,
in contrast to random attachment via native lysine residues. The results
of this study set the stage for the development of an EPR-based flow
system that will house soluble and membrane proteins immobilized site-specifically,
thereby enabling facile screening of structural and dynamical effects
of binding partners.
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Affiliation(s)
- Carlos J López
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States
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39
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Yang Z, Jiménez-Osés G, López CJ, Bridges MD, Houk KN, Hubbell WL. Long-range distance measurements in proteins at physiological temperatures using saturation recovery EPR spectroscopy. J Am Chem Soc 2014; 136:15356-65. [PMID: 25290172 PMCID: PMC4227719 DOI: 10.1021/ja5083206] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Indexed: 11/28/2022]
Abstract
Site-directed spin labeling in combination with EPR is a powerful method for providing distances on the nm scale in biological systems. The most popular strategy, double electron-electron resonance (DEER), is carried out at cryogenic temperatures (50-80 K) to increase the short spin-spin relaxation time (T2) upon which the technique relies. A challenge is to measure long-range distances (20-60 Å) in proteins near physiological temperatures. Toward this goal we are investigating an alternative approach based on the distance-dependent enhancement of spin-lattice relaxation rate (T1(-1)) of a nitroxide spin label by a paramagnetic metal. With a commonly used nitroxide side chain (R1) and Cu(2+), it has been found that interspin distances ≤25 Å can be determined in this way (Jun et al. Biochemistry 2006, 45, 11666). Here, the upper limit of the accessible distance is extended to ≈40 Å using spin labels with long T1, a high-affinity 5-residue Cu(2+) binding loop inserted into the protein sequence, and pulsed saturation recovery to measure relaxation enhancement. Time-domain Cu(2+) electron paramagnetic resonance, quantum mechanical calculations, and molecular dynamics simulations provide information on the structure and geometry of the Cu(2+) loop and indicate that the metal ion is well-localized in the protein. An important aspect of these studies is that both Cu(2+)/nitroxide DEER at cryogenic temperatures and T1 relaxation measurements at room temperature can be carried out on the same sample, allowing both validation of the relaxation method and assessment of the effect of freezing on protein structure.
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Affiliation(s)
- Zhongyu Yang
- Jules Stein Eye Institute and Department of
Chemistry and Biochemistry, University of
California, Los Angeles, California 90095, United States
| | - Gonzalo Jiménez-Osés
- Jules Stein Eye Institute and Department of
Chemistry and Biochemistry, University of
California, Los Angeles, California 90095, United States
| | - Carlos J. López
- Jules Stein Eye Institute and Department of
Chemistry and Biochemistry, University of
California, Los Angeles, California 90095, United States
| | | | - K. N. Houk
- Jules Stein Eye Institute and Department of
Chemistry and Biochemistry, University of
California, Los Angeles, California 90095, United States
| | - Wayne L. Hubbell
- Jules Stein Eye Institute and Department of
Chemistry and Biochemistry, University of
California, Los Angeles, California 90095, United States
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40
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Structural and energetic determinants of adhesive binding specificity in type I cadherins. Proc Natl Acad Sci U S A 2014; 111:E4175-84. [PMID: 25253890 DOI: 10.1073/pnas.1416737111] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Type I cadherin cell-adhesion proteins are similar in sequence and structure and yet are different enough to mediate highly specific cell-cell recognition phenomena. It has previously been shown that small differences in the homophilic and heterophilic binding affinities of different type I family members can account for the differential cell-sorting behavior. Here we use a combination of X-ray crystallography, analytical ultracentrifugation, surface plasmon resonance and double electron-electron resonance (DEER) electron paramagnetic resonance spectroscopy to identify the molecular determinants of type I cadherin dimerization affinities. Small changes in sequence are found to produce subtle structural and dynamical changes that impact relative affinities, in part via electrostatic and hydrophobic interactions, and in part through entropic effects because of increased conformational heterogeneity in the bound states as revealed by DEER distance mapping in the dimers. These findings highlight the remarkable ability of evolution to exploit a wide range of molecular properties to produce closely related members of the same protein family that have affinity differences finely tuned to mediate their biological roles.
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41
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Colloc'h N, Prangé T. Functional relevance of the internal hydrophobic cavity of urate oxidase. FEBS Lett 2014; 588:1715-9. [PMID: 24657440 DOI: 10.1016/j.febslet.2014.03.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/10/2014] [Accepted: 03/10/2014] [Indexed: 10/25/2022]
Abstract
Urate oxidase from Aspergillus flavus is a 135 kDa homo-tetramer which has a hydrophobic cavity buried within each monomer and located close to its active site. Crystallographic studies under moderate gas pressure and high hydrostatic pressure have shown that both gas presence and high pressure would rigidify the cavity leading to an inhibition of the catalytic activity. Analysis of the cavity volume variations and functional modifications suggest that the flexibility of the cavity would be an essential parameter for the active site efficiency. This cavity would act as a connecting vessel to give flexibility to the neighboring active site, and its expansion under pure oxygen pressure reveals that it might serve as a transient reservoir on its pathway to the active site.
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Affiliation(s)
- Nathalie Colloc'h
- CERVoxy Team, ISTCT UMR 6301, CNRS, Centre Cyceron, Caen, France; ISTCT UMR 6301, CEA, DSV/I2BM, Caen, France; ISTCT UMR 6301, Université de Caen Basse-Normandie, Normandie Université, Caen, France.
| | - Thierry Prangé
- LCRB UMR 8015, CNRS, Université Paris Descartes, Faculté de Pharmacie, 4 Avenue de l'Observatoire, 75006 Paris, France
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