1
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Li G, Meng J, Yu S, Bai X, Dai J, Song Y, Peng X, Zhao Q. Excited-State Dynamics of a CRABPII-Based Microbial Rhodopsin Mimic. J Phys Chem B 2024. [PMID: 38940335 DOI: 10.1021/acs.jpcb.4c01296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
Microbial rhodopsin, a pivotal photoreceptor protein, has garnered widespread application in diverse fields such as optogenetics, biotechnology, biodevices, etc. However, current microbial rhodopsins are all transmembrane proteins, which both complicates the investigation on the photoreaction mechanism and limits their further applications. Therefore, a specific mimic for microbial rhodopsin can not only provide a better model for understanding the mechanism but also can extend the applications. The human protein CRABPII turns out to be a good template for design mimics on rhodopsin due to the convenience in synthesis and the stability after mutations. Recently, Geiger et al. designed a new CRABPII-based mimic M1-L121E on microbial rhodopsin with the 13-cis, syn (13C) isomerization after irradiation. However, it still remains a question as to how similar it is compared with the natural microbial rhodopsin, in particular, in the aspect of the photoreaction dynamics. In this article, we investigate the excited-state dynamics of this mimic by measuring its transient absorption spectra. Our results reveal that there are two components in the solution of mimic M1-L121E at pH 8, known as protonated Schiff base (PSB) and unprotonated Schiff base (USB) states. In both states, the photoreaction process from 13-cis, syn(13C) to all-trans,anti (AT) is faster than that from the inverse direction. In addition, the photoreaction process in the PSB state is faster than that in the USB state. We compared the isomerization time of the PSB state to that of microbial rhodopsin. Our findings indicate that M1-L121E exhibits behaviors similar to those of microbial rhodopsins in the general pattern of PSB isomerization, where the isomerization from 13C to AT is much faster than its inverse direction. However, our results also reveal significant differences in the excited-state dynamics of the mimic relative to the native microbial rhodopsin, including the slower PSB isomerization rates as well as the unusual USB photoreaction dynamics at pH = 8. By elucidating the distinctive characteristics of mimics M1-L121E, this study enhances our understanding of microbial rhodopsin mimics and their potential applications.
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Affiliation(s)
- Gaoshang Li
- Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Jiajia Meng
- Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Shuang Yu
- MIIT Key Laboratory of Complex-field Intelligent Exploration, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
| | - Xiaolu Bai
- MIIT Key Laboratory of Complex-field Intelligent Exploration, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
| | - Jin Dai
- Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Yin Song
- MIIT Key Laboratory of Complex-field Intelligent Exploration, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
| | - Xubiao Peng
- Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
- Beijing Academy of Quantum Information Sciences, Beijing 100081, China
| | - Qing Zhao
- Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
- Beijing Academy of Quantum Information Sciences, Beijing 100081, China
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2
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Demoulin B, Maiuri M, Berbasova T, Geiger JH, Borhan B, Garavelli M, Cerullo G, Rivalta I. Control of Protonated Schiff Base Excited State Decay within Visual Protein Mimics: A Unified Model for Retinal Chromophores. Chemistry 2021; 27:16389-16400. [PMID: 34653286 DOI: 10.1002/chem.202102383] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Indexed: 11/07/2022]
Abstract
Artificial biomimetic chromophore-protein complexes inspired by natural visual pigments can feature color tunability across the full visible spectrum. However, control of excited state dynamics of the retinal chromophore, which is of paramount importance for technological applications, is lacking due to its complex and subtle photophysics/photochemistry. Here, ultrafast transient absorption spectroscopy and quantum mechanics/molecular mechanics simulations are combined for the study of highly tunable rhodopsin mimics, as compared to retinal chromophores in solution. Conical intersections and transient fluorescent intermediates are identified with atomistic resolution, providing unambiguous assignment of their ultrafast excited state absorption features. The results point out that the electrostatic environment of the chromophore, modified by protein point mutations, affects its excited state properties allowing control of its photophysics with same power of chemical modifications of the chromophore. The complex nature of such fine control is a fundamental knowledge for the design of bio-mimetic opto-electronic and photonic devices.
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Affiliation(s)
- Baptiste Demoulin
- Laboratoire de Chimie, Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, 69342, Lyon, France
| | - Margherita Maiuri
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano, Italy
| | - Tetyana Berbasova
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - James H Geiger
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Marco Garavelli
- Dipartimento di Chimica Industriale "Toso Montanari", Università degli Studi di Bologna, Viale del Risorgimento 4, 40136, Bologna, Italy
| | - Giulio Cerullo
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano, Italy
| | - Ivan Rivalta
- Laboratoire de Chimie, Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, 69342, Lyon, France.,Dipartimento di Chimica Industriale "Toso Montanari", Università degli Studi di Bologna, Viale del Risorgimento 4, 40136, Bologna, Italy
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3
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Broser M, Spreen A, Konold PE, Schiewer E, Adam S, Borin V, Schapiro I, Seifert R, Kennis JTM, Bernal Sierra YA, Hegemann P. NeoR, a near-infrared absorbing rhodopsin. Nat Commun 2020; 11:5682. [PMID: 33173168 PMCID: PMC7655827 DOI: 10.1038/s41467-020-19375-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 10/06/2020] [Indexed: 12/18/2022] Open
Abstract
The Rhizoclosmatium globosum genome encodes three rhodopsin-guanylyl cyclases (RGCs), which are predicted to facilitate visual orientation of the fungal zoospores. Here, we show that RGC1 and RGC2 function as light-activated cyclases only upon heterodimerization with RGC3 (NeoR). RGC1/2 utilize conventional green or blue-light-sensitive rhodopsins (λmax = 550 and 480 nm, respectively), with short-lived signaling states, responsible for light-activation of the enzyme. The bistable NeoR is photoswitchable between a near-infrared-sensitive (NIR, λmax = 690 nm) highly fluorescent state (QF = 0.2) and a UV-sensitive non-fluorescent state, thereby modulating the activity by NIR pre-illumination. No other rhodopsin has been reported so far to be functional as a heterooligomer, or as having such a long wavelength absorption or high fluorescence yield. Site-specific mutagenesis and hybrid quantum mechanics/molecular mechanics simulations support the idea that the unusual photochemical properties result from the rigidity of the retinal chromophore and a unique counterion triad composed of two glutamic and one aspartic acids. These findings substantially expand our understanding of the natural potential and limitations of spectral tuning in rhodopsin photoreceptors.
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Affiliation(s)
- Matthias Broser
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany.
| | - Anika Spreen
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
| | - Patrick E Konold
- Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Enrico Schiewer
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
| | - Suliman Adam
- Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Veniamin Borin
- Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Reinhard Seifert
- Molecular Sensory Systems, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175, Bonn, Germany
| | - John T M Kennis
- Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | | | - Peter Hegemann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
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4
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El‐Tahawy MMT, Conti I, Bonfanti M, Nenov A, Garavelli M. Tailoring Spectral and Photochemical Properties of Bioinspired Retinal Mimics by in Silico Engineering. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mohsen M. T. El‐Tahawy
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
- Chemistry Department Faculty of Science Damanhour University Damanhour 22511 Egypt
| | - Irene Conti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Matteo Bonfanti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Artur Nenov
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Marco Garavelli
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
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5
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El‐Tahawy MMT, Conti I, Bonfanti M, Nenov A, Garavelli M. Tailoring Spectral and Photochemical Properties of Bioinspired Retinal Mimics by in Silico Engineering. Angew Chem Int Ed Engl 2020; 59:20619-20627. [DOI: 10.1002/anie.202008644] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Mohsen M. T. El‐Tahawy
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
- Chemistry Department Faculty of Science Damanhour University Damanhour 22511 Egypt
| | - Irene Conti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Matteo Bonfanti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Artur Nenov
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Marco Garavelli
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
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6
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Santos EM, Berbasova T, Wang W, Salmani RE, Sheng W, Vasileiou C, Geiger JH, Borhan B. Engineering of a Red Fluorogenic Protein/Merocyanine Complex for Live-Cell Imaging. Chembiochem 2020; 21:723-729. [PMID: 31482666 PMCID: PMC7379159 DOI: 10.1002/cbic.201900428] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Indexed: 12/25/2022]
Abstract
A reengineered human cellular retinol binding protein II (hCRBPII), a 15-kDa protein belonging to the intracellular lipid binding protein (iLBP) family, generates a highly fluorescent red pigment through the covalent linkage of a merocyanine aldehyde to an active site lysine residue. The complex exhibits "turn-on" fluorescence, due to a weakly fluorescent aldehyde that "lights up" with subsequent formation of a strongly fluorescent merocyanine dye within the binding pocket of the protein. Cellular penetration of merocyanine is rapid, and fluorophore maturation is nearly instantaneous. The hCRBPII/merocyanine complex displays high quantum yield, low cytotoxicity, specificity in labeling organelles, and compatibility in both cancer cell lines and yeast cells. The hCRBPII/merocyanine tag is brighter than most common red fluorescent proteins.
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Affiliation(s)
- Elizabeth M. Santos
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln., East Lansing, MI 48824 USA
| | - Tetyana Berbasova
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln., East Lansing, MI 48824 USA
| | - Wenjing Wang
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln., East Lansing, MI 48824 USA
| | | | - Wei Sheng
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln., East Lansing, MI 48824 USA
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln., East Lansing, MI 48824 USA
| | - James H. Geiger
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln., East Lansing, MI 48824 USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln., East Lansing, MI 48824 USA
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7
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Biewenga L, Crotti M, Saifuddin M, Poelarends GJ. Selective Colorimetric "Turn-On" Probe for Efficient Engineering of Iminium Biocatalysis. ACS OMEGA 2020; 5:2397-2405. [PMID: 32064400 PMCID: PMC7017405 DOI: 10.1021/acsomega.9b03849] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/16/2020] [Indexed: 06/10/2023]
Abstract
The efficient engineering of iminium biocatalysis has drawn considerable attention, with many applications in pharmaceutical synthesis. Here, we report a tailor-made iminium-activated colorimetric "turn-on" probe, specifically designed as a prescreening tool to facilitate engineering of iminium biocatalysis. Upon complexation of the probe with the catalytic Pro-1 residue of the model enzyme 4-oxalocrotonate tautomerase (4-OT), a brightly colored merocyanine-dye-type structure is formed. 4-OT mutants that formed this brightly colored species upon incubation with the probe proved to have a substantial activity for the iminium-based Michael-type addition of nitromethane to cinnamaldehyde, whereas mutants that showed no staining by the probe exhibited no or very low-level "Michaelase" activity. This system was exploited in a solid-phase prescreening assay termed as activated iminium colony staining (AICS) to enrich libraries for active mutants. AICS prescreening reduced the screening effort up to 20-fold. After two rounds of directed evolution, two artificial Michaelases were identified with up to 39-fold improvement in the activity for the addition of nitromethane to cinnamaldehyde, yielding the target γ-nitroaldehyde product with excellent isolated yield (up to 95%) and enantiopurity (up to >99% ee). The colorimetric activation of the turn-on probe could be extended to the class I aldolase 2-deoxy-d-ribose 5-phosphate aldolase, implicating a broader application of AICS in engineering iminium biocatalysis.
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8
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Banerjee S, Mitra D. Structural Basis of Design and Engineering for Advanced Plant Optogenetics. TRENDS IN PLANT SCIENCE 2020; 25:35-65. [PMID: 31699521 DOI: 10.1016/j.tplants.2019.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 09/12/2019] [Accepted: 10/03/2019] [Indexed: 06/10/2023]
Abstract
In optogenetics, light-sensitive proteins are specifically expressed in target cells and light is used to precisely control the activity of these proteins at high spatiotemporal resolution. Optogenetics initially used naturally occurring photoreceptors to control neural circuits, but has expanded to include carefully designed and engineered photoreceptors. Several optogenetic constructs are based on plant photoreceptors, but their application to plant systems has been limited. Here, we present perspectives on the development of plant optogenetics, considering different levels of design complexity. We discuss how general principles of light-driven signal transduction can be coupled with approaches for engineering protein folding to develop novel optogenetic tools. Finally, we explore how the use of computation, networks, circular permutation, and directed evolution could enrich optogenetics.
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Affiliation(s)
- Sudakshina Banerjee
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata 700073, India
| | - Devrani Mitra
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata 700073, India.
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9
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Ghanbarpour A, Pinger C, Esmatpour Salmani R, Assar Z, Santos EM, Nosrati M, Pawlowski K, Spence D, Vasileiou C, Jin X, Borhan B, Geiger JH. Engineering the hCRBPII Domain-Swapped Dimer into a New Class of Protein Switches. J Am Chem Soc 2019; 141:17125-17132. [PMID: 31557439 DOI: 10.1021/jacs.9b04664] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Protein conformational switches or allosteric proteins play a key role in the regulation of many essential biological pathways. Nonetheless, the implementation of protein conformational switches in protein design applications has proven challenging, with only a few known examples that are not derivatives of naturally occurring allosteric systems. We have discovered that the domain-swapped (DS) dimer of hCRBPII undergoes a large and robust conformational change upon retinal binding, making it a potentially powerful template for the design of protein conformational switches. Atomic resolution structures of the apo- and holo-forms illuminate a simple, mechanical movement involving sterically driven torsion angle flipping of two residues that drive the motion. We further demonstrate that the conformational "readout" can be altered by addition of cross-domain disulfide bonds, also visualized at atomic resolution. Finally, as a proof of principle, we have created an allosteric metal binding site in the DS dimer, where ligand binding results in a reversible 5-fold loss of metal binding affinity. The high resolution structure of the metal-bound variant illustrates a well-formed metal binding site at the interface of the two domains of the DS dimer and confirms the design strategy for allosteric regulation.
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Affiliation(s)
- Alireza Ghanbarpour
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Cody Pinger
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Rahele Esmatpour Salmani
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Zahra Assar
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Elizabeth M Santos
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Meisam Nosrati
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Kathryn Pawlowski
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Dana Spence
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Chrysoula Vasileiou
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Xiangshu Jin
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Babak Borhan
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - James H Geiger
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
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10
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Pedraza-González L, De Vico L, del Carmen Marín M, Fanelli F, Olivucci M. a-ARM: Automatic Rhodopsin Modeling with Chromophore Cavity Generation, Ionization State Selection, and External Counterion Placement. J Chem Theory Comput 2019; 15:3134-3152. [PMID: 30916955 PMCID: PMC7141608 DOI: 10.1021/acs.jctc.9b00061] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Automatic Rhodopsin Modeling (ARM) protocol has recently been proposed as a tool for the fast and parallel generation of basic hybrid quantum mechanics/molecular mechanics (QM/MM) models of wild type and mutant rhodopsins. However, in its present version, input preparation requires a few hours long user's manipulation of the template protein structure, which also impairs the reproducibility of the generated models. This limitation, which makes model building semiautomatic rather than fully automatic, comprises four tasks: definition of the retinal chromophore cavity, assignment of protonation states of the ionizable residues, neutralization of the protein with external counterions, and finally congruous generation of single or multiple mutations. In this work, we show that the automation of the original ARM protocol can be extended to a level suitable for performing the above tasks without user's manipulation and with an input preparation time of minutes. The new protocol, called a-ARM, delivers fully reproducible (i.e., user independent) rhodopsin QM/MM models as well as an improved model quality. More specifically, we show that the trend in vertical excitation energies observed for a set of 25 wild type and 14 mutant rhodopsins is predicted by the new protocol better than when using the original. Such an agreement is reflected by an estimated (relative to the probed set) trend deviation of 0.7 ± 0.5 kcal mol-1 (0.03 ± 0.02 eV) and mean absolute error of 1.0 kcal mol-1 (0.04 eV).
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Affiliation(s)
- Laura Pedraza-González
- Department of Biotechnologies, Chemistry and Pharmacy, Università degli Studi di Siena, via A. Moro 2, I-53100 Siena, Italy
| | - Luca De Vico
- Department of Biotechnologies, Chemistry and Pharmacy, Università degli Studi di Siena, via A. Moro 2, I-53100 Siena, Italy
| | - María del Carmen Marín
- Department of Biotechnologies, Chemistry and Pharmacy, Università degli Studi di Siena, via A. Moro 2, I-53100 Siena, Italy
| | - Francesca Fanelli
- Department of Life Sciences, Center for Neuroscience and Neurotechnology, Università degli Studi di Modena e Reggio Emilia, I-41125 Modena, Italy
| | - Massimo Olivucci
- Department of Biotechnologies, Chemistry and Pharmacy, Università degli Studi di Siena, via A. Moro 2, I-53100 Siena, Italy
- Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States
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11
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Pagano K, Paolino M, Fusi S, Zanirato V, Trapella C, Giuliani G, Cappelli A, Zanzoni S, Molinari H, Ragona L, Olivucci M. Bile Acid Binding Protein Functionalization Leads to a Fully Synthetic Rhodopsin Mimic. J Phys Chem Lett 2019; 10:2235-2243. [PMID: 30995409 DOI: 10.1021/acs.jpclett.9b00210] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Rhodopsins are photoreceptive proteins using light to drive a plethora of biological functions such as vision, proton and ion pumping, cation and anion channeling, and gene and enzyme regulation. Here we combine organic synthesis, NMR structural studies, and photochemical characterization to show that it is possible to prepare a fully synthetic mimic of rhodopsin photoreceptors. More specifically, we conjugate a bile acid binding protein with a synthetic mimic of the rhodopsin protonated Schiff base chromophore to achieve a covalent complex featuring an unnatural protein host, photoswitch, and photoswitch-protein linkage with a reverse orientation. We show that, in spite of its molecular-level diversity, light irradiation of the prepared mimic fuels a photochromic cycle driven by sequential photochemical and thermal Z/E isomerizations reminiscent of the photocycles of microbial rhodopsins.
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Affiliation(s)
- Katiuscia Pagano
- Istituto per lo Studio delle Macromolecole, CNR , Via A. Corti 12 , 20133 Milano , Italy
| | - Marco Paolino
- Dipartimento di Biotecnologie, Chimica e Farmacia (Dipartimento di Eccellenza 2018-2022) , Università degli Studi di Siena , Via Aldo Moro 2 , 53100 Siena , Italy
| | - Stefania Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia (Dipartimento di Eccellenza 2018-2022) , Università degli Studi di Siena , Via Aldo Moro 2 , 53100 Siena , Italy
| | | | | | - Germano Giuliani
- Dipartimento di Biotecnologie, Chimica e Farmacia (Dipartimento di Eccellenza 2018-2022) , Università degli Studi di Siena , Via Aldo Moro 2 , 53100 Siena , Italy
| | - Andrea Cappelli
- Dipartimento di Biotecnologie, Chimica e Farmacia (Dipartimento di Eccellenza 2018-2022) , Università degli Studi di Siena , Via Aldo Moro 2 , 53100 Siena , Italy
| | - Serena Zanzoni
- Centro Piattaforme Tecnologiche , Università di Verona , Strada Le Grazie , 37134 Verona , Italy
| | - Henriette Molinari
- Istituto per lo Studio delle Macromolecole, CNR , Via A. Corti 12 , 20133 Milano , Italy
| | - Laura Ragona
- Istituto per lo Studio delle Macromolecole, CNR , Via A. Corti 12 , 20133 Milano , Italy
| | - Massimo Olivucci
- Dipartimento di Biotecnologie, Chimica e Farmacia (Dipartimento di Eccellenza 2018-2022) , Università degli Studi di Siena , Via Aldo Moro 2 , 53100 Siena , Italy
- Chemistry Department , Bowling Green State University , Bowling Green , Ohio 43403 , United States
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12
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Berbasova T, Tahmasebi Nick S, Nosrati M, Nossoni Z, Santos EM, Vasileiou C, Geiger JH, Borhan B. A Genetically Encoded Ratiometric pH Probe: Wavelength Regulation-Inspired Design of pH Indicators. Chembiochem 2018; 19:1288-1295. [PMID: 29645331 DOI: 10.1002/cbic.201800050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Indexed: 11/11/2022]
Abstract
Mutants of human cellular retinol-binding protein II (hCRBPII) were engineered to bind a julolidine retinal analogue for the purpose of developing a ratiometric pH sensor. The design relied on the electrostatic influence of a titratable amino acid side chain, which affects the absorption and, thus, the emission of the protein/fluorophore complex. The ratio of emissions obtained at two excitation wavelengths that correspond to the absorption of the two forms of the protein/fluorophore complex, leads to a concentration-independent measure of pH.
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Affiliation(s)
- Tetyana Berbasova
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | | | - Meisam Nosrati
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Zahra Nossoni
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Elizabeth M Santos
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - James H Geiger
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
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13
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Zhong HA, Santos EM, Vasileiou C, Zheng Z, Geiger JH, Borhan B, Merz KM. Free-Energy-Based Protein Design: Re-Engineering Cellular Retinoic Acid Binding Protein II Assisted by the Moveable-Type Approach. J Am Chem Soc 2018; 140:3483-3486. [PMID: 29480012 DOI: 10.1021/jacs.7b10368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
How to fine-tune the binding free energy of a small-molecule to a receptor site by altering the amino acid residue composition is a key question in protein engineering. Indeed, the ultimate solution to this problem, to chemical accuracy (±1 kcal/mol), will result in profound and wide-ranging applications in protein design. Numerous tools have been developed to address this question using knowledge-based models to more computationally intensive molecular dynamics simulations-based free energy calculations, but while some success has been achieved there remains room for improvement in terms of overall accuracy and in the speed of the methodology. Here we report a fast, knowledge-based movable-type (MT)-based approach to estimate the absolute and relative free energy of binding as influenced by mutations in a small-molecule binding site in a protein. We retrospectively validate our approach using mutagenesis data for retinoic acid binding to the Cellular Retinoic Acid Binding Protein II (CRABPII) system and then make prospective predictions that are borne out experimentally. The overall performance of our approach is supported by its success in identifying mutants that show high or even sub-nano-molar binding affinities of retinoic acid to the CRABPII system.
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Affiliation(s)
- Haizhen A Zhong
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States.,Department of Chemistry , University of Nebraska at Omaha , Omaha , Nebraska 68182 , United States
| | - Elizabeth M Santos
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Chrysoula Vasileiou
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Zheng Zheng
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - James H Geiger
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Babak Borhan
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Kenneth M Merz
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
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14
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Valdez CE, Morgenstern A, Eberhart ME, Alexandrova AN. Predictive methods for computational metalloenzyme redesign - a test case with carboxypeptidase A. Phys Chem Chem Phys 2018; 18:31744-31756. [PMID: 27841396 DOI: 10.1039/c6cp02247b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Computational metalloenzyme design is a multi-scale problem. It requires treating the metal coordination quantum mechanically, extensive sampling of the protein backbone, and additionally accounting for the polarization of the active site by both the metal cation and the surrounding protein (a phenomenon called electrostatic preorganization). We bring together a combination of theoretical methods that jointly offer these desired qualities: QM/DMD for mixed quantum-classical dynamic sampling, quantum theory of atoms in molecules (QTAIM) for the assessment of electrostatic preorganization, and Density Functional Theory (DFT) for mechanistic studies. Within this suite of principally different methods, there are both complementarity of capabilities and cross-validation. Using these methods, predictions can be made regarding the relative activities of related enzymes, as we show on the native Zn2+-dependent carboxypeptidase A (CPA), and its mutant proteins, which are hypothesized to hydrolyze modified substrates. For the native CPA, we replicated the catalytic mechanism and the rate in close agreement with the experiment, giving validity to the QM/DMD predicted structure, the DFT mechanism, and the QTAIM assessment of catalytic activity. For most sequences of the modified substrate and tried CPA mutants, substantially worsened activity is predicted. However, for the substrate mutant that contains Asp instead of Phe at the C-terminus, one CPA mutant exhibits a reasonable activity, as predicted across the theoretical methods. CPA is a well-studied system, and here it serves as a testing ground for the offered methods.
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Affiliation(s)
- Crystal E Valdez
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Amanda Morgenstern
- Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401, USA.
| | - Mark E Eberhart
- Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401, USA.
| | - Anastassia N Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA. and California NanoSystems Institute, Los Angeles, CA 90095, USA
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15
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Zhang S, Chen G, Wang Y, Wang Q, Zhong Y, Yang XF, Li Z, Li H. Far-Red Fluorescent Probe for Imaging of Vicinal Dithiol-Containing Proteins in Living Cells Based on a pKa Shift Mechanism. Anal Chem 2018; 90:2946-2953. [DOI: 10.1021/acs.analchem.7b05429] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Shengrui Zhang
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, People’s Republic of China
- Shaanxi
Key Laboratory of Catalysis, School of Chemistry and Environment Science, Shaanxi University of Technology, Hanzhong, Shaanxi 723000, People’s Republic of China
| | - Guojun Chen
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, People’s Republic of China
| | - Yuanyuan Wang
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, People’s Republic of China
| | - Qin Wang
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, People’s Republic of China
- Shaanxi
Key Laboratory of Catalysis, School of Chemistry and Environment Science, Shaanxi University of Technology, Hanzhong, Shaanxi 723000, People’s Republic of China
| | - Yaogang Zhong
- College
of Life Sciences, Northwest University, Xi’an, Shaanxi 710069, People’s Republic of China
| | - Xiao-Feng Yang
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, People’s Republic of China
| | - Zheng Li
- College
of Life Sciences, Northwest University, Xi’an, Shaanxi 710069, People’s Republic of China
| | - Hua Li
- College
of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, People’s Republic of China
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16
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Gozem S, Luk HL, Schapiro I, Olivucci M. Theory and Simulation of the Ultrafast Double-Bond Isomerization of Biological Chromophores. Chem Rev 2017; 117:13502-13565. [DOI: 10.1021/acs.chemrev.7b00177] [Citation(s) in RCA: 175] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Samer Gozem
- Department
of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Hoi Ling Luk
- Chemistry
Department, Bowling Green State University, Overman Hall, Bowling Green, Ohio 43403, United States
| | - Igor Schapiro
- Fritz
Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Massimo Olivucci
- Chemistry
Department, Bowling Green State University, Overman Hall, Bowling Green, Ohio 43403, United States
- Dipartimento
di Biotecnologie, Chimica e Farmacia, Università di Siena, via A. Moro
2, 53100 Siena, Italy
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17
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Assar Z, Nossoni Z, Wang W, Santos EM, Kramer K, McCornack C, Vasileiou C, Borhan B, Geiger JH. Domain-Swapped Dimers of Intracellular Lipid-Binding Proteins: Evidence for Ordered Folding Intermediates. Structure 2016; 24:1590-8. [PMID: 27524203 PMCID: PMC5330279 DOI: 10.1016/j.str.2016.05.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/13/2016] [Accepted: 05/16/2016] [Indexed: 11/29/2022]
Abstract
Human Cellular Retinol Binding Protein II (hCRBPII), a member of the intracellular lipid-binding protein family, is a monomeric protein responsible for the intracellular transport of retinol and retinal. Herein we report that hCRBPII forms an extensive domain-swapped dimer during bacterial expression. The domain-swapped region encompasses almost half of the protein. The dimer represents a novel structural architecture with the mouths of the two binding cavities facing each other, producing a new binding cavity that spans the length of the protein complex. Although wild-type hCRBPII forms the dimer, the propensity for dimerization can be substantially increased via mutation at Tyr60. The monomeric form of the wild-type protein represents the thermodynamically more stable species, making the domain-swapped dimer a kinetically trapped entity. Hypothetically, the wild-type protein has evolved to minimize dimerization of the folding intermediate through a critical hydrogen bond (Tyr60-Glu72) that disfavors the dimeric form.
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Affiliation(s)
- Zahra Assar
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Zahra Nossoni
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Wenjing Wang
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Elizabeth M Santos
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Kevin Kramer
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Colin McCornack
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
| | - James H Geiger
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
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18
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Nosrati M, Berbasova T, Vasileiou C, Borhan B, Geiger JH. A Photoisomerizing Rhodopsin Mimic Observed at Atomic Resolution. J Am Chem Soc 2016; 138:8802-8. [PMID: 27310917 DOI: 10.1021/jacs.6b03681] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The members of the rhodopsin family of proteins are involved in many essential light-dependent processes in biology. Specific photoisomerization of the protein-bound retinylidene PSB at a specified wavelength range of light is at the heart of all of these systems. Nonetheless, it has been difficult to reproduce in an engineered system. We have developed rhodopsin mimics, using intracellular lipid binding protein family members as scaffolds, to study fundamental aspects of protein/chromophore interactions. Herein we describe a system that specifically isomerizes the retinylidene protonated Schiff base both thermally and photochemically. This isomerization has been characterized at atomic resolution by quantitatively interconverting the isomers in the crystal both thermally and photochemically. This event is accompanied by a large pKa change of the imine similar to the pKa changes observed in bacteriorhodopsin and visual opsins during isomerization.
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Affiliation(s)
- Meisam Nosrati
- Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| | - Tetyana Berbasova
- Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| | - Babak Borhan
- Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| | - James H Geiger
- Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
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19
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Berbasova T, Santos EM, Nosrati M, Vasileiou C, Geiger JH, Borhan B. Light-Activated Reversible Imine Isomerization: Towards a Photochromic Protein Switch. Chembiochem 2016; 17:407-14. [PMID: 26684483 PMCID: PMC4835339 DOI: 10.1002/cbic.201500613] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Indexed: 01/07/2023]
Abstract
Mutants of cellular retinoic acid-binding protein II (CRABPII), engineered to bind all-trans-retinal as an iminium species, demonstrate photochromism upon irradiation with light at different wavelengths. UV light irradiation populates the cis-imine geometry, which has a high pKa , leading to protonation of the imine and subsequent "turn-on" of color. Yellow light irradiation yields the trans-imine isomer, which has a depressed pKa , leading to loss of color because the imine is not protonated. The protein-bound retinylidene chromophore undergoes photoinduced reversible interconversion between the colored and uncolored species, with excellent fatigue resistance.
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Affiliation(s)
- Tetyana Berbasova
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Elizabeth M Santos
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Meisam Nosrati
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - James H Geiger
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
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20
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Yapici I, Lee KSS, Berbasova T, Nosrati M, Jia X, Vasileiou C, Wang W, Santos EM, Geiger JH, Borhan B. "Turn-on" protein fluorescence: in situ formation of cyanine dyes. J Am Chem Soc 2015; 137:1073-80. [PMID: 25534273 PMCID: PMC4311949 DOI: 10.1021/ja506376j] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Protein reengineering of cellular retinoic acid binding protein II (CRABPII) has yielded a genetically addressable system, capable of binding a profluorophoric chromophore that results in fluorescent protein/chromophore complexes. These complexes exhibit far-red emission, with high quantum efficiencies and brightness and also exhibit excellent pH stability spanning the range of 2-11. In the course of this study, it became evident that single mutations of L121E and R59W were most effective in improving the fluorescent characteristics of CRABPII mutants as well as the kinetics of complex formation. The readily crystallizable nature of these proteins was invaluable to provide clues for the observed spectroscopic behavior that results from single mutation of key residues.
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Affiliation(s)
- Ipek Yapici
- Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
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21
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Nossoni Z, Assar Z, Yapici I, Nosrati M, Wang W, Berbasova T, Vasileiou C, Borhan B, Geiger J. Structures of holo wild-type human cellular retinol-binding protein II (hCRBPII) bound to retinol and retinal. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:3226-32. [PMID: 25478840 PMCID: PMC4257620 DOI: 10.1107/s1399004714023839] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/29/2014] [Indexed: 11/10/2022]
Abstract
Cellular retinol-binding proteins (CRBPs) I and II, which are members of the intracellular lipid-binding protein (iLBP) family, are retinoid chaperones that are responsible for the intracellular transport and delivery of both retinol and retinal. Although structures of retinol-bound CRBPI and CRBPII are known, no structure of a retinal-bound CRBP has been reported. In addition, the retinol-bound human CRBPII (hCRBPII) structure shows partial occupancy of a noncanonical conformation of retinol in the binding pocket. Here, the structure of retinal-bound hCRBPII and the structure of retinol-bound hCRBPII with retinol fully occupying the binding pocket are reported. It is further shown that the retinoid derivative seen in both the zebrafish CRBP and the hCRBPII structures is likely to be the product of flux-dependent and wavelength-dependent X-ray damage during data collection. The structures of retinoid-bound CRBPs are compared and contrasted, and rationales for the differences in binding affinities for retinal and retinol are provided.
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Affiliation(s)
- Zahra Nossoni
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - Zahra Assar
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - Ipek Yapici
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - Meisam Nosrati
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - Wenjing Wang
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - Tetyana Berbasova
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
| | - James Geiger
- Department of Chemistry, Michigan State University, East Lansing, MI 48864, USA
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22
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Light SH, Minasov G, Duban ME, Anderson WF. Adherence to Bürgi-Dunitz stereochemical principles requires significant structural rearrangements in Schiff-base formation: insights from transaldolase complexes. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:544-52. [PMID: 24531488 PMCID: PMC3940192 DOI: 10.1107/s1399004713030666] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 11/08/2013] [Indexed: 11/10/2022]
Abstract
The Bürgi-Dunitz angle (αBD) describes the trajectory of approach of a nucleophile to an electrophile. The adoption of a stereoelectronically favorable αBD can necessitate significant reactive-group repositioning over the course of bond formation. In the context of enzyme catalysis, interactions with the protein constrain substrate rotation, which could necessitate structural transformations during bond formation. To probe this theoretical framework vis-à-vis biocatalysis, Schiff-base formation was analysed in Francisella tularensis transaldolase (TAL). Crystal structures of wild-type and Lys→Met mutant TAL in covalent and noncovalent complexes with fructose 6-phosphate and sedoheptulose 7-phosphate clarify the mechanism of catalysis and reveal that substrate keto moieties undergo significant conformational changes during Schiff-base formation. Structural changes compelled by the trajectory considerations discussed here bear relevance to bond formation in a variety of constrained enzymic/engineered systems and can inform the design of covalent therapeutics.
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Affiliation(s)
- Samuel H. Light
- Center for Structural Genomics of Infectious Diseases, USA
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - George Minasov
- Center for Structural Genomics of Infectious Diseases, USA
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Mark-Eugene Duban
- Center for Structural Genomics of Infectious Diseases, USA
- Department of Chemistry and Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, IL 60201, USA
| | - Wayne F. Anderson
- Center for Structural Genomics of Infectious Diseases, USA
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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23
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Berbasova T, Nosrati M, Vasileiou C, Wang W, Lee KSS, Yapici I, Geiger JH, Borhan B. Rational design of a colorimetric pH sensor from a soluble retinoic acid chaperone. J Am Chem Soc 2013; 135:16111-9. [PMID: 24059243 PMCID: PMC4104655 DOI: 10.1021/ja404900k] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Reengineering of cellular retinoic acid binding protein II (CRABPII) to be capable of binding retinal as a protonated Schiff base is described. Through rational alterations of the binding pocket, electrostatic perturbations of the embedded retinylidene chromophore that favor delocalization of the iminium charge lead to exquisite control in the regulation of chromophoric absorption properties, spanning the visible spectrum (474-640 nm). The pKa of the retinylidene protonated Schiff base was modulated from 2.4 to 8.1, giving rise to a set of proteins of varying colors and pH sensitivities. These proteins were used to demonstrate a concentration-independent, ratiometric pH sensor.
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Affiliation(s)
- Tetyana Berbasova
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Meisam Nosrati
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Wenjing Wang
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Kin Sing Stephen Lee
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Ipek Yapici
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - James H. Geiger
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
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24
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Wang W, Geiger JH, Borhan B. The photochemical determinants of color vision: revealing how opsins tune their chromophore's absorption wavelength. Bioessays 2013; 36:65-74. [PMID: 24323922 DOI: 10.1002/bies.201300094] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The evolution of a variety of important chromophore-dependent biological processes, including microbial light sensing and mammalian color vision, relies on protein modifications that alter the spectral characteristics of a bound chromophore. Three different color opsins share the same chromophore, but have three distinct absorptions that together cover the entire visible spectrum, giving rise to trichromatic vision. The influence of opsins on the absorbance of the chromophore has been studied through methods such as model compounds, opsin mutagenesis, and computational modeling. The recent development of rhodopsin mimic that uses small soluble proteins to recapitulate the binding and wavelength tuning of the native opsins provides a new platform for studying protein-regulated spectral tuning. The ability to achieve far-red shifted absorption in the rhodopsin mimic system was attributed to a combination of the lack of a counteranion proximal to the iminium, and a uniformly neutral electrostatic environment surrounding the chromophore.
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Affiliation(s)
- Wenjing Wang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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25
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Abstract
Rhodopsins are photochemically reactive membrane proteins that covalently bind retinal chromophores. Type I rhodopsins are found in both prokaryotes and eukaryotic microbes, whereas type II rhodopsins function as photoactivated G-protein coupled receptors (GPCRs) in animal vision. Both rhodopsin families share the seven transmembrane α-helix GPCR fold and a Schiff base linkage from a conserved lysine to retinal in helix G. Nevertheless, rhodopsins are widely cited as a striking example of evolutionary convergence, largely because the two families lack detectable sequence similarity and differ in many structural and mechanistic details. Convergence entails that the shared rhodopsin fold is so especially suited to photosensitive function that proteins from separate origins were selected for this architecture twice. Here we show, however, that the rhodopsin fold is not required for photosensitive activity. We engineered functional bacteriorhodopsin variants with novel folds, including radical noncircular permutations of the α-helices, circular permutations of an eight-helix construct, and retinal linkages relocated to other helices. These results contradict a key prediction of convergence and thereby provide an experimental attack on one of the most intractable problems in molecular evolution: how to establish structural homology for proteins devoid of discernible sequence similarity.
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26
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Gozem S, Melaccio F, Lindh R, Krylov AI, Granovsky AA, Angeli C, Olivucci M. Mapping the Excited State Potential Energy Surface of a Retinal Chromophore Model with Multireference and Equation-of-Motion Coupled-Cluster Methods. J Chem Theory Comput 2013; 9:4495-506. [DOI: 10.1021/ct400460h] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Samer Gozem
- Department
of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Federico Melaccio
- Dipartimento
di Biotecnologie, Chimica e Farmacia, Università di Siena, via A. Moro
2, I-53100 Siena, Italy
| | - Roland Lindh
- Department
of Chemistry, Ångström, the Theoretical Chemistry Programme, POB 518, SE-751 20 Uppsala, Sweden
| | - Anna I. Krylov
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | | | - Celestino Angeli
- Dipartimento
di Chimica, Università di Ferrara, via Borsari 46, I-44121 Ferrara, Italy
| | - Massimo Olivucci
- Department
of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States
- Dipartimento
di Biotecnologie, Chimica e Farmacia, Università di Siena, via A. Moro
2, I-53100 Siena, Italy
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27
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Huntress MM, Gozem S, Malley KR, Jailaubekov AE, Vasileiou C, Vengris M, Geiger JH, Borhan B, Schapiro I, Larsen DS, Olivucci M. Toward an Understanding of the Retinal Chromophore in Rhodopsin Mimics. J Phys Chem B 2013; 117:10053-70. [DOI: 10.1021/jp305935t] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mark M. Huntress
- Department of Chemistry, Bowling Green State University, Bowling Green, Ohio
43402, United States
| | - Samer Gozem
- Department of Chemistry, Bowling Green State University, Bowling Green, Ohio
43402, United States
| | - Konstantin R. Malley
- Department
of Chemistry, University of California Davis, One Shields Avenure,
Davis, California 95616, United States
| | - Askat E. Jailaubekov
- Department
of Chemistry, University of California Davis, One Shields Avenure,
Davis, California 95616, United States
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, Lansing, Michigan 48824,
United States
| | - Mikas Vengris
- Department
of Chemistry, University of California Davis, One Shields Avenure,
Davis, California 95616, United States
- Faculty of
Physics, Vilnius University, Sauletekio
10 LT10223 Vilnius,
Lithuania
| | - James H. Geiger
- Department of Chemistry, Michigan State University, Lansing, Michigan 48824,
United States
| | - Babak Borhan
- Department of Chemistry, Michigan State University, Lansing, Michigan 48824,
United States
| | - Igor Schapiro
- Department of Chemistry, Bowling Green State University, Bowling Green, Ohio
43402, United States
| | - Delmar S. Larsen
- Department
of Chemistry, University of California Davis, One Shields Avenure,
Davis, California 95616, United States
| | - Massimo Olivucci
- Department of Chemistry, Bowling Green State University, Bowling Green, Ohio
43402, United States
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28
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Relocating the active-site lysine in rhodopsin and implications for evolution of retinylidene proteins. Proc Natl Acad Sci U S A 2013; 110:13351-5. [PMID: 23904486 DOI: 10.1073/pnas.1306826110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Type I and type II rhodopsins share several structural features including a G protein-coupled receptor fold and a highly conserved active-site Lys residue in the seventh transmembrane segment of the protein. However, the two families lack significant sequence similarity that would indicate common ancestry. Consequently, the rhodopsin fold and conserved Lys are widely thought to have arisen from functional constraints during convergent evolution. To test for the existence of such a constraint, we asked whether it were possible to relocate the highly conserved Lys296 in the visual pigment bovine rhodopsin. We show here that the Lys can be moved to three other locations in the protein while maintaining the ability to form a pigment with 11-cis-retinal and activate the G protein transducin in a light-dependent manner. These results contradict the convergent hypothesis and support the homology of type I and type II rhodopsins by divergent evolution from a common ancestral protein.
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29
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Affiliation(s)
- Thomas P Sakmar
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, NY 10065, USA.
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30
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Wang W, Nossoni Z, Berbasova T, Watson CT, Yapici I, Lee KSS, Vasileiou C, Geiger JH, Borhan B. Tuning the electronic absorption of protein-embedded all-trans-retinal. Science 2012; 338:1340-3. [PMID: 23224553 DOI: 10.1126/science.1226135] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Protein-chromophore interactions are a central component of a wide variety of critical biological processes such as color vision and photosynthesis. To understand the fundamental elements that contribute to spectral tuning of a chromophore inside the protein cavity, we redesigned human cellular retinol binding protein II (hCRBPII) to fully encapsulate all-trans-retinal and form a covalent bond as a protonated Schiff base. This system, using rational mutagenesis designed to alter the electrostatic environment within the binding pocket of the host protein, enabled regulation of the absorption maximum of the pigment in the range of 425 to 644 nanometers. With only nine point mutations, the hCRBPII mutants induced a systematic shift in the absorption profile of all-trans-retinal of more than 200 nanometers across the visible spectrum.
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Affiliation(s)
- Wenjing Wang
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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31
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Lee KSS, Morisseau C, Yang J, Wang P, Hwang SH, Hammock BD. Förster resonance energy transfer competitive displacement assay for human soluble epoxide hydrolase. Anal Biochem 2012; 434:259-68. [PMID: 23219719 DOI: 10.1016/j.ab.2012.11.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 11/15/2012] [Accepted: 11/25/2012] [Indexed: 01/10/2023]
Abstract
The soluble epoxide hydrolase (sEH), responsible for the hydrolysis of various fatty acid epoxides to their corresponding 1,2-diols, is becoming an attractive pharmaceutical target. These fatty acid epoxides, particularly epoxyeicosatrienoic acids (EETs), play an important role in human homeostatic and inflammation processes. Therefore, inhibition of human sEH, which stabilizes EETs in vivo, brings several beneficial effects to human health. Although there are several catalytic assays available to determine the potency of sEH inhibitors, measuring the in vitro inhibition constant (K(i)) for these inhibitors using catalytic assay is laborious. In addition, k(off), which has been recently suggested to correlate better with the in vivo potency of inhibitors, has never been measured for sEH inhibitors. To better measure the potency of sEH inhibitors, a reporting ligand, 1-(adamantan-1-yl)-3-(1-(2-(7-hydroxy-2-oxo-2H-chromen-4-yl)acetyl) piperidin-4-yl)urea (ACPU), was designed and synthesized. With ACPU, we have developed a Förster resonance energy transfer (FRET)-based competitive displacement assay using intrinsic tryptophan fluorescence from sEH. In addition, the resulting assay allows us to measure the K(i) values of very potent compounds to the picomolar level and to obtain relative k(off) values of the inhibitors. This assay provides additional data to evaluate the potency of sEH inhibitors.
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Affiliation(s)
- Kin Sing Stephen Lee
- Department of Entomology and UCD Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
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32
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Systematic interaction analysis of human lipocalin-type prostaglandin D synthase with small lipophilic ligands. Biochem J 2012; 446:279-89. [DOI: 10.1042/bj20120324] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
L-PGDS [lipocalin-type PG (prostaglandin) D synthase] is a multi-functional protein, acting as a PGD2-producing enzyme and a lipid-transporter. In the present study, we focus on the function of L-PGDS as an extracellular transporter for small lipophilic molecules. We characterize the binding mechanism of human L-PGDS for the molecules, especially binding affinity stoichiometry and driving force, using tryptophan fluorescence quenching, ICD (induced circular dichroism) and ITC (isothermal titration calorimetry). The tryptophan fluorescence quenching measurements revealed that haem metabolites such as haemin, biliverdin and bilirubin bind to L-PGDS with significantly higher affinities than the other small lipophilic ligands examined, showing dissociation constant (Kd) values from 17.0 to 20.9 nM. We focused particularly on the extra-specificities of haem metabolites and L-PGDS. The ITC and ICD data revealed that two molecules of the haem metabolites bind to L-PGDS with high and low affinities, showing Kd values from 2.8 to 18.1 nM and from 0.209 to 1.63 μM respectively. The thermodynamic parameters for the interactions revealed that the contributions of enthalpy and entropy change were considerably different for each haem metabolite even when the Gibbs energy change was the same. Thus we believe that the binding energy of haem metabolites to L-PGDS is optimized by balancing enthalpy and entropy change.
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33
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Marincean S, Rabago Smith M, Beltz L, Borhan B. Selectivity of labeled bromoethylamine for protein alkylation. J Mol Model 2012; 18:4547-56. [PMID: 22643979 DOI: 10.1007/s00894-012-1461-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 05/04/2012] [Indexed: 11/25/2022]
Abstract
Alkylation of cysteine residues has been used extensively for characterization of proteins and their mode of action in biological systems, research endeavors that are at the core of proteomics. Treatment with a simple alkylating agent such as [2-(13)C] bromoethylamine would result in labeled thialysine at the ε-position. This chemical modification of proteins would allow investigations via both (13)C NMR spectroscopy and mass spectrometry. However [2-(13)C] labeled bromoethylamine is not available commercially. We investigated its synthesis at acid pH with the goal of obtaining singly labeled bromoethylamine and understanding the mechanistic details of the reaction. Based on our experimental and theoretical results, bromination of [2-(13)C] labeled ethanolamine in acidic conditions takes place via exclusive attack of the nucleophile (HBr) at the hydroxyl bearing C. Moreover, hydrogen bonding guides the nucleophilic attack, resulting in no label scrambling of the bromoethylamine product. Protein alkylation at cysteine residue with the synthesized Br(13)CH(2)CH(2)NH(2)-HBr is successful. Ab initio calculations in which CH(3)SH serves as a model for the cysteine residue suggest that in gas phase intermolecular attack by the sulfur bearing nucleophile is favored over the intramolecular substitution by the amino group by 15.4 kJ mol(-1). Solution modeling shows that the trend is preserved at basic pH, which is the experimental one, but is reversed at neutral pH.
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Affiliation(s)
- Simona Marincean
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, MI 48128, USA.
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34
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Lee KSS, Berbasova T, Vasileiou C, Jia X, Wang W, Choi Y, Nossoni F, Geiger JH, Borhan B. Probing Wavelength Regulation with an Engineered Rhodopsin Mimic and a C15-Retinal Analogue. Chempluschem 2012. [DOI: 10.1002/cplu.201100082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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35
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Tomaselli S, Assfalg M, Pagano K, Cogliati C, Zanzoni S, Molinari H, Ragona L. A Disulfide Bridge Allows for Site-Selective Binding in Liver Bile Acid Binding Protein Thereby Stabilising the Orientation of Key Amino Acid Side Chains. Chemistry 2012; 18:2857-66. [DOI: 10.1002/chem.201102203] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 12/05/2011] [Indexed: 11/08/2022]
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36
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Li X, Fu Z, Merz KM. QM/MM refinement and analysis of protein bound retinoic acid. J Comput Chem 2012; 33:301-10. [PMID: 22108894 PMCID: PMC3240731 DOI: 10.1002/jcc.21978] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/13/2011] [Accepted: 09/28/2011] [Indexed: 11/12/2022]
Abstract
Retinoic acid (RA) is a vitamin A derivative, which modifies the appearance of fine wrinkles and roughness of facial skin and treats acne and activates gene transcription by binding to heterodimers of the retinoic acid receptor (RAR) and the retinoic X receptor (RXR). There are series of protein bound RA complexes available in the protein databank (PDB), which provides a broad range of information about the different bioactive conformations of RA. To gain further insights into the observed bioactive RA conformations we applied quantum mechanic (QM)/molecular mechanic (MM) approaches to re-refine the available RA protein-ligand complexes. MP2 complete basis set (CBS) extrapolations single energy calculations are also carried out for both the experimental conformations and QM optimized geometries of RA in the gas as well as solution phase. The results demonstrate that the re-refined structures show better geometries for RA than seen in the originally deposited PDB structures through the use of QMs for the ligand in the X-ray refinement procedure. QM/MM re-refined conformations also reduced the computed strain energies found in the deposited crystal conformations for RA. Finally, the dependence of ligand strain on resolution is analyzed. It is shown that ligand strain is not converged in our calculations and is likely an artifact of the typical resolutions employed to study protein-ligand complexes.
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Affiliation(s)
- Xue Li
- Department of Chemistry, Quantum Theory Project, University of Florida, Gainesville, Florida 32611, USA
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37
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Sparta M, Alexandrova AN. Computational design and characterisation of artificial enzymes for Kemp elimination. MOLECULAR SIMULATION 2011. [DOI: 10.1080/08927022.2011.565760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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38
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Blanco S, López JC, Mata S, Alonso JL. Conformations of γ-Aminobutyric Acid (GABA): The Role of the n→π* Interaction. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201002535] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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39
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Blanco S, López JC, Mata S, Alonso JL. Conformations of γ-Aminobutyric Acid (GABA): The Role of the n→π* Interaction. Angew Chem Int Ed Engl 2010; 49:9187-92. [DOI: 10.1002/anie.201002535] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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40
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Rodríguez H, Angulo I, de Las Rivas B, Campillo N, Páez JA, Muñoz R, Mancheño JM. p-Coumaric acid decarboxylase from Lactobacillus plantarum: structural insights into the active site and decarboxylation catalytic mechanism. Proteins 2010; 78:1662-76. [PMID: 20112419 DOI: 10.1002/prot.22684] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
p-Coumaric acid decarboxylases (PDCs) catalyze the nonoxidative decarboxylation of hydroxycinnamic acids to generate the corresponding vinyl derivatives. Despite the biotechnological relevance of PDCs in food industry, their catalytic mechanism remains largely unknown. Here, we report insights into the structural basis of catalysis for the homodimeric PDC from Lactobacillus plantarum (LpPDC). The global fold of LpPDC is based on a flattened beta-barrel surrounding an internal cavity. Crystallographic and functional analyses of single-point mutants of residues located within this cavity have permitted identifying a potential substrate-binding pocket and also to provide structural evidences for rearrangements of surface loops so that they can modulate the accessibility to the active site. Finally, combination of the structural and functional data with in silico results enables us to propose a two-step catalytic mechanism for decarboxylation of p-coumaric acid by PDCs where Glu71 is involved in proton transfer, and Tyr18 and Tyr20 are involved in the proper substrate orientation and in the release of the CO(2) product.
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Affiliation(s)
- Héctor Rodríguez
- Departamento de Microbiología, Instituto de Fermentaciones Industriales, CSIC, Juan de la Cierva 3, E-28006 Madrid, Spain
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41
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Vasileiou C, Lee KSS, Crist RM, Vaezeslami S, Goins SM, Geiger JH, Borhan B. Dissection of the critical binding determinants of cellular retinoic acid binding protein II by mutagenesis and fluorescence binding assay. Proteins 2010; 76:281-90. [PMID: 19156818 DOI: 10.1002/prot.22334] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The binding of retinoic acid to mutants of Cellular Retinoic Acid Binding Protein II (CRABPII) was evaluated to better understand the importance of the direct protein/ligand interactions. The important role of Arg111 for the correct structure and function of the protein was verified and other residues that directly affect retinoic acid binding have been identified. Furthermore, retinoic acid binding to CRABPII mutants that lack all previously identified interacting amino acids was rescued by providing a carboxylic acid dimer partner in the form of a Glu residue.
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Affiliation(s)
- Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, East Lansing, 48824, USA
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42
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Vasileiou C, Wang W, Jia X, Lee KSS, Watson CT, Geiger JH, Borhan B. Elucidating the exact role of engineered CRABPII residues for the formation of a retinal protonated Schiff base. Proteins 2010; 77:812-22. [PMID: 19603486 DOI: 10.1002/prot.22495] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cellular Retinoic Acid Binding Protein II (CRABPII) has been reengineered to specifically bind and react with all-trans-retinal to form a protonated Schiff base. Each step of this process has been dissected and four residues (Lys132, Tyr134, Arg111, and Glu121) within the CRABPII binding site have been identified as crucial for imine formation and/or protonation. The precise role of each residue has been examined through site directed mutagenesis and crystallographic studies. The crystal structure of the R132K:L121E-CRABPII (PDB-3I17) double mutant suggests a direct interaction between engineered Glu121 and the native Arg111, which is critical for both Schiff base formation and protonation.
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Affiliation(s)
- Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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43
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Alexandrova AN, Röthlisberger D, Baker D, Jorgensen WL. Catalytic mechanism and performance of computationally designed enzymes for Kemp elimination. J Am Chem Soc 2009; 130:15907-15. [PMID: 18975945 DOI: 10.1021/ja804040s] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of enzymes for Kemp elimination of 5-nitrobenzisoxazole has been recently designed and tested. In conjunction with the design process, extensive computational analyses were carried out to evaluate the potential performance of four of the designs, as presented here. The enzyme-catalyzed reactions were modeled using mixed quantum and molecular mechanics (QM/MM) calculations in the context of Monte Carlo (MC) statistical mechanics simulations. Free-energy perturbation (FEP) calculations were used to characterize the free-energy surfaces for the catalyzed reactions as well as for reference processes in water. The simulations yielded detailed information about the catalytic mechanisms, activation barriers, and structural evolution of the active sites over the course of the reactions. The catalytic mechanism for the designed enzymes KE07, KE10(V131N), and KE15 was found to be concerted with proton transfer, generally more advanced in the transition state than breaking of the isoxazolyl N-O bond. On the basis of the free-energy results, all three enzymes were anticipated to be active. Ideas for further improvement of the enzyme designs also emerged. On the technical side, the synergy of parallel QM/MM and experimental efforts in the design of artificial enzymes is well illustrated.
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Affiliation(s)
- Anastassia N Alexandrova
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
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44
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Alexandrova AN, Jorgensen WL. Origin of the activity drop with the E50D variant of catalytic antibody 34E4 for Kemp elimination. J Phys Chem B 2009; 113:497-504. [PMID: 19132861 DOI: 10.1021/jp8076084] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In enzymes, multiple structural effects cooperatively lead to the high catalytic activity, while individually these effects can be small. The design of artificial enzymes requires the understanding and ability to manipulate such subtle effects. The 34E4 catalytic antibody, catalyzing Kemp elimination of 5-nitrobenzisoxazole, and its Glu50Asp (E50D) variant are the subject of the present investigation. This removal of only a methylene group yields an approximately 30-fold reduction in the rate for the catalyzed Kemp elimination. Here, the aim is to understand this difference in the catalytic performance. The mechanism of Kemp elimination catalyzed by 34E4 and the E50D mutant is elucidated using QM/MM Monte Carlo simulations and free energy perturbation theory. In both proteins, the reaction is shown to follow a single-step, concerted mechanism. In the mutant, the activation barrier rises by 2.4 kcal/mol, which corresponds to a 62-fold rate deceleration, which is in good agreement with the experimental data. The positions and functionality of the residues in the active site are monitored throughout the reaction. It is concluded that the looser contact with the base, shorter base-Asn58 contact, less favorable pi-stacking with Trp91 in the transition state of the reaction, and different solvation pattern all contribute to the reduction of the reaction rate in the E50D variant of 34E4.
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Affiliation(s)
- Anastassia N Alexandrova
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
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45
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Vaezeslami S, Jia X, Vasileiou C, Borhan B, Geiger JH. Structural analysis of site-directed mutants of cellular retinoic acid-binding protein II addresses the relationship between structural integrity and ligand binding. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2008; 64:1228-39. [PMID: 19018099 PMCID: PMC2631107 DOI: 10.1107/s0907444908032216] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Accepted: 10/06/2008] [Indexed: 11/10/2022]
Abstract
The structural integrity of cellular retinoic acid-binding protein II (CRABPII) has been investigated using the crystal structures of CRABPII mutants. The overall fold was well maintained by these CRABPII mutants, each of which carried multiple different mutations. A water-mediated network is found to be present across the large binding cavity, extending from Arg111 deep inside the cavity to the alpha2 helix at its entrance. This chain of interactions acts as a ;pillar' that maintains the integrity of the protein. The disruption of the water network upon loss of Arg111 leads to decreased structural integrity of the protein. A water-mediated network can be re-established by introducing the hydrophilic Glu121 inside the cavity, which results in a rigid protein with the alpha2 helix adopting an altered conformation compared with wild-type CRABPII.
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Affiliation(s)
- Soheila Vaezeslami
- Rigaku Americas Corporation, 9009 New Trails Drive, The Woodlands, TX 77381, USA
| | - Xiaofei Jia
- Chemistry Department, Michigan State University, East Lansing, MI 48824-1322, USA
| | - Chrysoula Vasileiou
- Chemistry Department, Michigan State University, East Lansing, MI 48824-1322, USA
| | - Babak Borhan
- Chemistry Department, Michigan State University, East Lansing, MI 48824-1322, USA
| | - James H. Geiger
- Chemistry Department, Michigan State University, East Lansing, MI 48824-1322, USA
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