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Zhang H, Zhang T, Saravanan KM, Liao L, Wu H, Zhang H, Zhang H, Pan Y, Wu X, Wei Y. DeepBindBC: a practical deep learning method for identifying native-like protein-ligand complexes in virtual screening. Methods 2022; 205:247-262. [PMID: 35878751 DOI: 10.1016/j.ymeth.2022.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 06/29/2022] [Accepted: 07/12/2022] [Indexed: 12/18/2022] Open
Abstract
Identifying native-like protein-ligand complexes (PLCs) from an abundance of docking decoys is critical for large-scale virtual drug screening in early-stage drug discovery lead searching efforts. Providing reliable prediction is still a challenge for most current affinity predicting models because of a lack of non-binding data during model training, lost critical physical-chemical features, and difficulties in learning abstract information with limited neural layers. In this work, we proposed a deep learning model, DeepBindBC, for classifying putative ligands as binding or non-binding. Our model incorporates information on non-binding interactions, making it more suitable for real applications. ResNet model architecture and more detailed atom type representation guarantee implicit features can be learned more accurately. Here, we show that DeepBindBC outperforms Autodock Vina, Pafnucy, and DLSCORE for three DUD.E testing sets. Moreover, DeepBindBC identified a novel human pancreatic α-amylase binder validated by a fluorescence spectral experiment (Ka= 1.0×105 M). Furthermore, DeepBindBC can be used as a core component of a hybrid virtual screening pipeline that incorporating many other complementary methods, such as DFCNN, Autodock Vina docking, and pocket molecular dynamics simulation. Additionally, an online web server based on the model is available at http://cbblab.siat.ac.cn/DeepBindBC/index.php for the user's convenience. Our model and the web server provide alternative tools in the early steps of drug discovery by providing accurate identification of native-like PLCs.
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Affiliation(s)
- Haiping Zhang
- Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, PR China; Center for High Performance Computing, Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518 055, PR China
| | - Tingting Zhang
- School of Medicine, Shenzhen University, Shenzhen, Guangdong Province 518060, PR China
| | - Konda Mani Saravanan
- Department of Biotechnology, Bharath Institute of Higher Education and Research, Chennai 600073, Tamil Nadu, India
| | - Linbu Liao
- College of Software Technology, Zhejiang University, Zhejiang Province 315048, PR China
| | - Hao Wu
- Center for High Performance Computing, Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518 055, PR China
| | - Haishan Zhang
- Center for High Performance Computing, Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518 055, PR China
| | - Huiling Zhang
- Center for High Performance Computing, Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518 055, PR China
| | - Yi Pan
- Center for High Performance Computing, Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518 055, PR China
| | - Xuli Wu
- School of Medicine, Shenzhen University, Shenzhen, Guangdong Province 518060, PR China.
| | - Yanjie Wei
- Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, PR China.
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Rius J, Torrelles X. A new density-modification procedure extending the application of the recent |ρ|-based phasing algorithm to larger crystal structures. Acta Crystallogr A Found Adv 2021; 77:339-347. [PMID: 34196295 PMCID: PMC8248888 DOI: 10.1107/s2053273321004915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 05/10/2021] [Indexed: 11/10/2022] Open
Abstract
The incorporation of the new peakness-enhancing fast Fourier transform compatible ipp procedure (ipp = inner-pixel preservation) into the recently published SM algorithm based on |ρ| [Rius (2020). Acta Cryst A76, 489-493] improves its phasing efficiency for larger crystal structures with atomic resolution data. Its effectiveness is clearly demonstrated via a collection of test crystal structures (taken from the Protein Data Bank) either starting from random phase values or by using the randomly shifted modulus function (a Patterson-type synthesis) as initial ρ estimate. It has been found that in the presence of medium scatterers (e.g. S or Cl atoms) crystal structures with 1500 × c atoms in the unit cell (c = number of centerings) can be routinely solved. In the presence of strong scatterers like Fe, Cu or Zn atoms this number increases to around 5000 × c atoms. The implementation of this strengthened SM algorithm is simple, since it only includes a few easy-to-adjust parameters.
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Affiliation(s)
- Jordi Rius
- Institut de Ciència de Materials de Barcelona, CSIC, Campus de la UAB, Bellaterra, Catalonia 08193, Spain
| | - Xavier Torrelles
- Institut de Ciència de Materials de Barcelona, CSIC, Campus de la UAB, Bellaterra, Catalonia 08193, Spain
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Szuster J, Zitare UA, Castro MA, Leguto AJ, Morgada MN, Vila AJ, Murgida DH. Cu A-based chimeric T1 copper sites allow for independent modulation of reorganization energy and reduction potential. Chem Sci 2020; 11:6193-6201. [PMID: 32953013 PMCID: PMC7480511 DOI: 10.1039/d0sc01620a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 06/01/2020] [Indexed: 01/19/2023] Open
Abstract
Attaining rational modulation of thermodynamic and kinetic redox parameters of metalloproteins is a key milestone towards the (re)design of proteins with new or improved redox functions. Here we report that implantation of ligand loops from natural T1 proteins into the scaffold of a CuA protein leads to a series of distorted T1-like sites that allow for independent modulation of reduction potentials (E°') and electron transfer reorganization energies (λ). On the one hand E°' values could be fine-tuned over 120 mV without affecting λ. On the other, λ values could be modulated by more than a factor of two while affecting E°' only by a few millivolts. These results are in sharp contrast to previous studies that used T1 cupredoxin folds, thus highlighting the importance of the protein scaffold in determining such parameters.
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Affiliation(s)
- Jonathan Szuster
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE, CONICET-UBA) , Argentina .
- Departamento de Química Inorgánica, Analítica y Química-Física , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires , Buenos Aires , Argentina
| | - Ulises A Zitare
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE, CONICET-UBA) , Argentina .
- Departamento de Química Inorgánica, Analítica y Química-Física , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires , Buenos Aires , Argentina
| | - María A Castro
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE, CONICET-UBA) , Argentina .
- Departamento de Química Inorgánica, Analítica y Química-Física , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires , Buenos Aires , Argentina
| | - Alcides J Leguto
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) , Argentina
- Departamento de Química Biológica , Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Rosario , Argentina
| | - Marcos N Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) , Argentina
- Departamento de Química Biológica , Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Rosario , Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) , Argentina
- Departamento de Química Biológica , Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Rosario , Argentina
| | - Daniel H Murgida
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE, CONICET-UBA) , Argentina .
- Departamento de Química Inorgánica, Analítica y Química-Física , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires , Buenos Aires , Argentina
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Gavrilov Y, Dagan S, Reich Z, Scherf T, Levy Y. An NMR Confirmation for Increased Folded State Entropy Following Loop Truncation. J Phys Chem B 2018; 122:10855-10860. [PMID: 30411894 DOI: 10.1021/acs.jpcb.8b09658] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Previous studies conducted on flexible loop regions in proteins revealed that the energetic consequences of changing loop length predominantly arise from the entropic cost of ordering a loop during folding. However, in an earlier study of human acylphosphatase (hmAcP) using experimental and computational approaches, we showed that thermodynamic stabilization upon loop truncation can be attributed mainly to the increased entropy of the folded state. Here, using 15N NMR spectroscopy, we studied the effect of loop truncation on hmAcP backbone dynamics on the picosecond-nanosecond timescale with the aim of confirming the effect of folded state entropy on protein stability. NMR-relaxation-derived N-H squared generalized order parameters reveal that loop truncation results in a significant increase in protein conformational flexibility. Comparison of these results with previously acquired all-atom molecular dynamics simulation, analyzed here in terms of squared generalized NMR order parameters, demonstrates general agreement between the two methods. The NMR study not only provides direct evidence for the enhanced conformational entropy of the folded state of hmAcP upon loop truncation but also gives a quantitative measure of the observed effects.
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5
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Espinoza-Cara A, Zitare U, Alvarez-Paggi D, Klinke S, Otero LH, Murgida DH, Vila AJ. Engineering a bifunctional copper site in the cupredoxin fold by loop-directed mutagenesis. Chem Sci 2018; 9:6692-6702. [PMID: 30310603 PMCID: PMC6115626 DOI: 10.1039/c8sc01444b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 06/27/2018] [Indexed: 12/30/2022] Open
Abstract
Copper sites in proteins are designed to perform either electron transfer or redox catalysis. Type 1 and CuA sites are electron transfer hubs bound to a rigid protein fold that prevents binding of exogenous ligands and side reactions. Here we report the engineering of two Type 1 sites by loop-directed mutagenesis within a CuA scaffold with unique electronic structures and functional features. A copper-thioether axial bond shorter than the copper-thiolate bond is responsible for the electronic structure features, in contrast to all other natural or chimeric sites where the copper thiolate bond is short. These sites display highly unusual features, such as: (1) a high reduction potential despite a strong interaction with the axial ligand, which we attribute to changes in the hydrogen bond network and (2) the ability to bind exogenous ligands such as imidazole and azide. This strategy widens the possibility of using natural protein scaffolds with functional features not present in nature.
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Affiliation(s)
- Andrés Espinoza-Cara
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) , Rosario , Argentina .
- Área Biofísica , Departamento de Química Biológica , Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Rosario , Argentina
| | - Ulises Zitare
- Departamento de Química Inorgánica , Analítica y Química Física-INQUIMAE , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires-CONICET , Buenos Aires , Argentina
| | - Damián Alvarez-Paggi
- Departamento de Química Inorgánica , Analítica y Química Física-INQUIMAE , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires-CONICET , Buenos Aires , Argentina
- Fundación Instituto Leloir , IIBBA-CONICET , Buenos Aires , Argentina
| | - Sebastián Klinke
- Fundación Instituto Leloir , IIBBA-CONICET , Buenos Aires , Argentina
- Plataforma Argentina de Biología Estructural y Metabolómica PLABEM. , Buenos Aires , Argentina
| | - Lisandro H Otero
- Fundación Instituto Leloir , IIBBA-CONICET , Buenos Aires , Argentina
- Plataforma Argentina de Biología Estructural y Metabolómica PLABEM. , Buenos Aires , Argentina
| | - Daniel H Murgida
- Departamento de Química Inorgánica , Analítica y Química Física-INQUIMAE , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires-CONICET , Buenos Aires , Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) , Rosario , Argentina .
- Área Biofísica , Departamento de Química Biológica , Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Rosario , Argentina
- Plataforma Argentina de Biología Estructural y Metabolómica PLABEM. , Buenos Aires , Argentina
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Chen H, Su B, Zhang T, Huang A, Liu H, Yu Y, Wang J. Engineering the metal-binding loop at a type 1 copper center by circular permutation. RSC Adv 2017. [DOI: 10.1039/c7ra11512a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Circular permutation of the cupredoxin azurin creates a break on the metal binding loop, highlighting the loop's flexibility.
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Affiliation(s)
- Honghui Chen
- College of Biotechnology
- Tianjin University of Science and Technology
- Tianjin
- China
- Tianjin Institute of Industrial Biotechnology
| | - Binbin Su
- College of Biotechnology
- Tianjin University of Science and Technology
- Tianjin
- China
- Tianjin Institute of Industrial Biotechnology
| | - Tongtong Zhang
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Aiping Huang
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Haiping Liu
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Yang Yu
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Jiangyun Wang
- Laboratory of RNA Biology
- Institute of Biophysics
- Chinese Academy of Sciences
- Beijing
- China
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7
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Sadhu B, Sundararajan M. Asn47 and Phe114 modulate the inner sphere reorganization energies of type zero copper proteins. Phys Chem Chem Phys 2016; 18:16748-56. [PMID: 27271560 DOI: 10.1039/c6cp00747c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The geometric structures and electron transfer properties of type 1 Cu proteins are reasonably understood at the molecular level (E. I. Solomon and R. G. Hadt, Coord. Chem. Rev., 2011, 255, 774-789, J. J. Warren, K. M. Lancaster, J. H. Richards and H. B. Gray, J. Inorg. Biochem., 2012, 115, 119-126). Much understanding of type 1 copper electron transfer reactivity has come from site directed mutagenesis studies. For example, artificial "type zero" Cu-centres constructed in cupredoxin-azurin have showcased the capacity of outer-sphere hydrogen bonding networks to enhance Cu II/I electron transfer reactivity. In this paper, we have elaborated on earlier kinetics and electronic structural studies of type zero Cu by calculating the inner sphere reorganization energies of type 1, type 2, and type zero Cu proteins using density functional theory (DFT). Although the choice of density functionals for copper systems is not straightforward, we have benchmarked the density functionals against the recently reported ESI-PES data for two synthetic copper models (S. Niu, D.-L. Huang, P. D. Dau, H.-T. Liu, L.-S. Wang and T. J. Ichiye, Chem. Theory Comput., 2014, 10, 1283). For the Cu proteins, our calculations predict that changes in the coordination number upon metal reduction lead to large inner sphere reorganization energies for type 2 Cu sites, whereas retention in the coordination number is observed for type zero Cu sites. These variations in the coordination number are modulated by the outer-sphere coordinating residues Asn47 and Phe114, which are involved in hydrogen bonding with the Asp112 side chain.
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Affiliation(s)
- Biswajit Sadhu
- Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai - 400 085, India
| | - Mahesh Sundararajan
- Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai - 400 094, India.
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8
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Gavrilov Y, Dagan S, Levy Y. Shortening a loop can increase protein native state entropy. Proteins 2015; 83:2137-46. [PMID: 26369935 DOI: 10.1002/prot.24926] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/20/2015] [Accepted: 09/01/2015] [Indexed: 01/31/2023]
Abstract
Protein loops are essential structural elements that influence not only function but also protein stability and folding rates. It was recently reported that shortening a loop in the AcP protein may increase its native state conformational entropy. This effect on the entropy of the folded state can be much larger than the lower entropic penalty of ordering a shorter loop upon folding, and can therefore result in a more pronounced stabilization than predicted by polymer model for loop closure entropy. In this study, which aims at generalizing the effect of loop length shortening on native state dynamics, we use all-atom molecular dynamics simulations to study how gradual shortening a very long or solvent-exposed loop region in four different proteins can affect their stability. For two proteins, AcP and Ubc7, we show an increase in native state entropy in addition to the known effect of the loop length on the unfolded state entropy. However, for two permutants of SH3 domain, shortening a loop results only with the expected change in the entropy of the unfolded state, which nicely reproduces the observed experimental stabilization. Here, we show that an increase in the native state entropy following loop shortening is not unique to the AcP protein, yet nor is it a general rule that applies to all proteins following the truncation of any loop. This modification of the loop length on the folded state and on the unfolded state may result with a greater effect on protein stability.
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Affiliation(s)
- Yulian Gavrilov
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Shlomi Dagan
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yaakov Levy
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
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Roger M, Biaso F, Castelle CJ, Bauzan M, Chaspoul F, Lojou E, Sciara G, Caffarri S, Giudici-Orticoni MT, Ilbert M. Spectroscopic characterization of a green copper site in a single-domain cupredoxin. PLoS One 2014; 9:e98941. [PMID: 24932914 PMCID: PMC4059628 DOI: 10.1371/journal.pone.0098941] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/09/2014] [Indexed: 12/13/2022] Open
Abstract
Cupredoxins are widespread copper-binding proteins, mainly involved in electron transfer pathways. They display a typical rigid greek key motif consisting of an eight stranded β-sandwich. A fascinating feature of cupredoxins is the natural diversity of their copper center geometry. These geometry variations give rise to drastic changes in their color, such as blue, green, red or purple. Based on several spectroscopic and structural analyses, a connection between the geometry of their copper-binding site and their color has been proposed. However, little is known about the relationship between such diversity of copper center geometry in cupredoxins and possible implications for function. This has been difficult to assess, as only a few naturally occurring green and red copper sites have been described so far. We report herein the spectrocopic characterization of a novel kind of single domain cupredoxin of green color, involved in a respiratory pathway of the acidophilic organism Acidithiobacillus ferrooxidans. Biochemical and spectroscopic characterization coupled to bioinformatics analysis reveal the existence of some unusual features for this novel member of the green cupredoxin sub-family. This protein has the highest redox potential reported to date for a green-type cupredoxin. It has a constrained green copper site insensitive to pH or temperature variations. It is a green-type cupredoxin found for the first time in a respiratory pathway. These unique properties might be explained by a region of unknown function never found in other cupredoxins, and by an unusual length of the loop between the second and the fourth copper ligands. These discoveries will impact our knowledge on non-engineered green copper sites, whose involvement in respiratory chains seems more widespread than initially thought.
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Affiliation(s)
- Magali Roger
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Frédéric Biaso
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Cindy J. Castelle
- Department of Earth and Planetary Science, University of California, Berkeley, California, United States of America
| | - Marielle Bauzan
- Unité de Fermentation, Institut de Microbiologie de la Méditerranée, CNRS-FR 3479, Aix Marseille Université, Marseille, France
| | - Florence Chaspoul
- Unité Chimie Physique, Prévention des Risques et Nuisances Technologiques, Faculté de Pharmacie, CNRS-UMR 7263, Aix-Marseille Université, Marseille, France
| | - Elisabeth Lojou
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Giuliano Sciara
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Stefano Caffarri
- Unité de Biologie Végétale et Microbiologie Environnementales, CNRS-UMR 7265, CEA, Aix Marseille Université, Marseille, France
| | - Marie-Thérèse Giudici-Orticoni
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Marianne Ilbert
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
- * E-mail:
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Abriata LA, Vila AJ, Dal Peraro M. Molecular dynamics simulations of apocupredoxins: insights into the formation and stabilization of copper sites under entatic control. J Biol Inorg Chem 2014; 19:565-75. [PMID: 24477946 DOI: 10.1007/s00775-014-1108-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/30/2013] [Indexed: 10/25/2022]
Abstract
Cupredoxins perform copper-mediated long-range electron transfer (ET) in biological systems. Their copper-binding sites have evolved to force copper ions into ET-competent systems with decreased reorganization energy, increased reduction potential, and a distinct electronic structure compared with those of non-ET-competent copper complexes. The entatic or rack-induced state hypothesis explains these special properties in terms of the strain that the protein matrix exerts on the metal ions. This idea is supported by X-ray structures of apocupredoxins displaying "closed" arrangements of the copper ligands like those observed in the holoproteins; however, it implies completely buried copper-binding atoms, conflicting with the notion that they must be exposed for copper loading. On the other hand, a recent work based on NMR showed that the copper-binding regions of apocupredoxins are flexible in solution. We have explored five cupredoxins in their "closed" apo forms through molecular dynamics simulations. We observed that prearranged ligand conformations are not stable as the X-ray data suggest, although they do form part of the dynamic landscape of the apoproteins. This translates into variable flexibility of the copper-binding regions within a rigid fold, accompanied by fluctuations of the hydrogen bonds around the copper ligands. Major conformations with solvent-exposed copper-binding atoms could allow initial binding of the copper ions. An eventual subsequent incursion to the closed state would result in binding of the remaining ligands, trapping the closed conformation thanks to the additional binding energy and the fastening of noncovalent interactions that make up the rack.
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Affiliation(s)
- Luciano A Abriata
- Laboratory of Biomolecular Modeling, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland,
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11
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Paltrinieri L, Borsari M, Battistuzzi G, Sola M, Dennison C, de Groot BL, Corni S, Bortolotti CA. How the dynamics of the metal-binding loop region controls the acid transition in cupredoxins. Biochemistry 2013; 52:7397-404. [PMID: 24063705 DOI: 10.1021/bi400860n] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many reduced cupredoxins undergo a pH-dependent structural rearrangement, triggered by protonation of the His ligand belonging to the C-terminal hydrophobic loop, usually termed the acid transition. At variance with several members of the cupredoxin family, the acid transition is not observed for azurin (AZ). We have addressed this issue by performing molecular dynamics simulations of AZ and four mutants, in which the C-terminal loop has been replaced with those of other cupredoxins or with polyalanine loops. All of the loop mutants undergo the acid transition in the pH range of 4.4-5.5. The main differences between AZ and its loop mutants are the average value of the active site solvent accessible surface area and the extent of its fluctuations with time, together with an altered structure of the water layer around the copper center. Using functional mode analysis, we found that these variations arise from changes in nonbonding interactions in the second coordination sphere of the copper center, resulting from the loop mutation. Our results strengthen the view that the dynamics at the site relevant for function and its surroundings are crucial for protein activity and for metal-containing electron transferases.
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Affiliation(s)
- Licia Paltrinieri
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , via Campi 183, 41125 Modena, Italy
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12
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Nasoohi N, Khajeh K, Mohammadian M, Ranjbar B. Enhancement of catalysis and functional expression of a bacterial laccase by single amino acid replacement. Int J Biol Macromol 2013; 60:56-61. [PMID: 23707861 DOI: 10.1016/j.ijbiomac.2013.05.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 05/09/2013] [Accepted: 05/15/2013] [Indexed: 12/01/2022]
Abstract
Structure-function relationships underlying laccases properties are very limited that makes these enzymes interesting for protein engineering approaches. Therefore in the current study, a thermostable laccase that was isolated from Bacillus sp. HR03 with the ability of bilirubin oxidation besides its laccase and tyrosinase activity is used. The extensive application of this enzyme is limited by its low expression level in Escherichia coli. Based on sequence alignments and structural studies, three single amino acid substitutions, D500G, D500E, D500S and a glycine insertion, are introduced using site-directed mutagenesis to evaluate the role of Asp(500) located in the C-terminal segment close to the T1 copper center. Substitution of aspartic acid with less sterically hindered, conserved residue such as glycine increase kcat (2.3 fold) and total activity (7.3 fold) which is accompanied by a significant increase in the expression level up to 3 fold. Biochemical characterization and structural studies using far-UV CD and fluorescence spectroscopy reveal the importance of C-terminal copper-binding loop in the laccase functional expression and catalytic efficiency. Kinetic characterization of the purified mutants toward 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), syringaldazine (SGZ) and bilirubin, shows that substrate specificity is left unchanged.
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Affiliation(s)
- Nikoo Nasoohi
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
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13
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Paltrinieri L, Borsari M, Ranieri A, Battistuzzi G, Corni S, Bortolotti CA. The Active Site Loop Modulates the Reorganization Energy of Blue Copper Proteins by Controlling the Dynamic Interplay with Solvent. J Phys Chem Lett 2013; 4:710-715. [PMID: 26281923 DOI: 10.1021/jz302125k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding the factors governing the rate of electron transfer processes in proteins is crucial not only to a deeper understanding of redox processes in living organisms but also for the design of efficient devices featuring biological molecules. Here, molecular dynamics simulations performed on native azurin and four chimeric cupredoxins allow for the calculation of the reorganization energy and of structure-related quantities that were used to clarify the molecular determinants to the dynamics/function relationship in blue copper proteins. We find that the dynamics of the small, metal-binding loop region controls the outer-sphere reorganization energy not only by determining the exposure of the active site to solvent but also through the modulation of the redox-dependent rearrangement of the whole protein scaffold and of the surrounding water molecules.
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Affiliation(s)
| | | | | | | | - Stefano Corni
- ¶CNR-Nano Institute of Nanoscience, via Campi 213/A, 41125 Modena, Italy
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14
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Allen S, Badarau A, Dennison C. The influence of protein folding on the copper affinities of trafficking and target sites. Dalton Trans 2012; 42:3233-9. [PMID: 23169585 DOI: 10.1039/c2dt32166a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The relative influence of protein unfolding on the Cu(I) affinity of trafficking and target sites for copper has been determined. For the copper metallochaperone Atx1 from Synechocystis PCC 6803 (a cyanobacterium), Saccharomyces cerevisiae and humans unfolding in urea results in a decrease in the Cu(I) affinity from (4-5) × 10(17) M(-1) to (1-3) × 10(16) M(-1) at pH 7. The affinities of the unfolded Atx1s are similar to those for CXXC-containing peptides. Partial unfolding, due to the loop 5 His61Lys mutation in Synechocystis Atx1, gives rise to a more limited decrease in Cu(I) affinity. For the copper target protein plastocyanin from Synechocystis, chemical unfolding results in the Cu(I) affinity decreasing by 5-orders of magnitude. This differential influence of protein unfolding on Cu(I) affinity is due to a more complex copper site structure in the target protein, including numerous interactions of non-coordinating residues with ligating amino acids. This second-coordination sphere is much simpler in the Atx1s with the main interaction provided by the loop 5 residue that tunes the Cu(I) affinity by altering the pK(a) of the C-terminal Cys ligand of the CXXC motif. This interaction and others are absent in the unfolded Atx1s and the two Cys ligands have pK(a) values reminiscent of free thiols (>8) resulting in lowered Cu(I) affinities at pH 7. Residues close to the active site of the thiol-disulfide oxidoreductase thioredoxin appear to lower the Cu(I) affinity of its CXXC motif to 3.1 × 10(15) M(-1) at pH 7, presumably to prevent copper binding in vivo. The structure of a copper site, including the number and relative position of ligands in the primary structure and the complexity of the second-coordination sphere, results in dramatically different effects of unfolding on Cu(I) affinity that has important implications for copper homeostasis.
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Affiliation(s)
- Stephen Allen
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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15
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Monari S, Battistuzzi G, Bortolotti CA, Yanagisawa S, Sato K, Li C, Salard I, Kostrz D, Borsari M, Ranieri A, Dennison C, Sola M. Understanding the Mechanism of Short-Range Electron Transfer Using an Immobilized Cupredoxin. J Am Chem Soc 2012; 134:11848-51. [DOI: 10.1021/ja303425b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stefano Monari
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Gianantonio Battistuzzi
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Carlo A. Bortolotti
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
- CNR-NANO Institute of Nanoscience, Via Campi 213/A, I-41125 Modena, Italy
| | - Sachiko Yanagisawa
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Katsuko Sato
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Chan Li
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Isabelle Salard
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Dorota Kostrz
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Marco Borsari
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Antonio Ranieri
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Christopher Dennison
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Marco Sola
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
- CNR-NANO Institute of Nanoscience, Via Campi 213/A, I-41125 Modena, Italy
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Adikaram PR, Beckett D. Functional versatility of a single protein surface in two protein:protein interactions. J Mol Biol 2012; 419:223-33. [PMID: 22446587 DOI: 10.1016/j.jmb.2012.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 03/12/2012] [Accepted: 03/14/2012] [Indexed: 11/18/2022]
Abstract
The ability of the Escherichia coli protein BirA to function as both a metabolic enzyme and a transcription repressor relies on the use of a single surface for two distinct protein:protein interactions. BirA forms a heterodimer with the biotin acceptor protein of acetyl-coenzyme A carboxylase and catalyzes posttranslational biotinylation. Alternatively, it forms a homodimer that binds sequence-specifically to DNA to repress transcription initiation at the biotin biosynthetic operon. Several surface loops on BirA, two of which exhibit sequence conservation in all biotin protein ligases and the remainder of which are highly variable, are located at the two interfaces. The function of these loops in both homodimerization and biotin transfer was investigated by characterizing alanine-substituted variants at 18 positions of one constant and three variable loops. Sedimentation equilibrium measurements reveal that 11 of the substitutions, which are distributed throughout conserved and variable loops, significantly alter homodimerization energetics. By contrast, steady-state and single-turnover kinetic measurements indicate that biotin transfer to biotin carboxyl carrier protein is impacted by seven substitutions, the majority of which are in the constant loop. Furthermore, constant loop residues that function in biotin transfer also support homodimerization. The results reveal clues about the evolution of a single protein surface for use in two distinct functions.
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Affiliation(s)
- Poorni R Adikaram
- Department of Chemistry and Biochemistry and Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742, USA
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17
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Guzzi R, Sportelli L, Yanagisawa S, Li C, Kostrz D, Dennison C. The influence of active site loop mutations on the thermal stability of azurin from Pseudomonas aeruginosa. Arch Biochem Biophys 2012; 521:18-23. [PMID: 22446157 DOI: 10.1016/j.abb.2012.03.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 03/05/2012] [Accepted: 03/06/2012] [Indexed: 10/28/2022]
Abstract
The copper site and overall structures of azurin (AZ) variants in which the amicyanin (AMI) and plastocyanin (PC) metal binding loops have been introduced, AZAMI and AZPC, respectively, are similar to that of AZ, whereas the loop conformations resemble those in the native proteins. To assess the influence of these loop mutations on stability, the thermal unfolding of AZAMI and AZPC has been investigated by differential scanning calorimetry, absorption and fluorescence spectroscopy. The calorimetric profiles of both variants exhibit a complex shape consisting of two endothermic peaks and an exothermic peak. The temperature of the maximum heat of absorption for the single endothermic peak is 82.7°C for AZ, whereas for AZAMI and AZPC the most intense endothermic peaks are at 74.9 and 68.1°C comparable to values for AMI and PC, respectively. Denaturation investigated using the temperature dependence of the absorbance at ∼600nm and Trp emission, also demonstrates decreased stability for both loop mutants. The thermal transition between the native and the denaturated states is irreversible, scan rate dependent and consistent with the two-state irreversible model. The structure of the active-site loop has a dramatic effect on the kinetic stability and the unfolding pathway of cupredoxins.
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Affiliation(s)
- Rita Guzzi
- Molecular Biophysics Laboratory and CNISM Unit, Department of Physics, University of Calabria, Ponte P. Bucci, Cubo 31C, 87036 Rende (CS), Italy.
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18
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Alagaratnam S, Meeuwenoord NJ, Navarro JA, Hervás M, De la Rosa MA, Hoffmann M, Einsle O, Ubbink M, Canters GW. Probing the reactivity of different forms of azurin by flavin photoreduction. FEBS J 2011; 278:1506-21. [DOI: 10.1111/j.1742-4658.2011.08067.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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19
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Incorporation of the red copper nitrosocyanin binding loop into blue copper azurin. J Biol Inorg Chem 2010; 16:473-80. [DOI: 10.1007/s00775-010-0746-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 11/24/2010] [Indexed: 10/18/2022]
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20
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Li C, Sato K, Monari S, Salard I, Sola M, Banfield MJ, Dennison C. Metal-Binding Loop Length Is a Determinant of the pKa of a Histidine Ligand at a Type 1 Copper Site. Inorg Chem 2010; 50:482-8. [DOI: 10.1021/ic101413e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Chan Li
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katsuko Sato
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Stefano Monari
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183, 41125 Modena, Italy
| | - Isabelle Salard
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Marco Sola
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183, 41125 Modena, Italy
| | - Mark J. Banfield
- Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH, U.K
| | - Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
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21
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Rajapandian V, Hakkim V, Subramanian V. Molecular Dynamics Studies on Native, Loop-Contracted, and Metal Ion-Substituted Azurins. J Phys Chem B 2010; 114:8474-86. [DOI: 10.1021/jp911301v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- V. Rajapandian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Hakkim
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Subramanian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
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