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Kipouros I, Stańczak A, Dunietz EM, Ginsbach JW, Srnec M, Rulíšek L, Solomon EI. Experimental Evidence and Mechanistic Description of the Phenolic H-Transfer to the Cu 2O 2 Active Site of oxy-Tyrosinase. J Am Chem Soc 2023; 145:22866-22870. [PMID: 37844210 PMCID: PMC10615789 DOI: 10.1021/jacs.3c07450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Tyrosinase is a ubiquitous coupled binuclear copper enzyme that activates O2 toward the regioselective monooxygenation of monophenols to catechols via a mechanism that remains only partially defined. Here, we present new mechanistic insights into the initial steps of this monooxygenation reaction by employing a pre-steady-state, stopped-flow kinetics approach that allows for the direct measurement of the monooxygenation rates for a series of para-substituted monophenols by oxy-tyrosinase. The obtained biphasic Hammett plot and the associated solvent kinetic isotope effect values provide direct evidence for an initial H-transfer from the protonated phenolic substrate to the Cu2O2 core of oxy-tyrosinase. The correlation of these experimental results to quantum mechanics/molecular mechanics calculations provides a detailed mechanistic description of this H-transfer step. These new mechanistic insights revise and expand our fundamental understanding of Cu2O2 active sites in biology.
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Affiliation(s)
- Ioannis Kipouros
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Agnieszka Stańczak
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10, Praha 6, Czech Republic
- Faculty of Science, Charles University, Albertov 2038/6, 128 00 Praha 2, Czech Republic
| | - Eleanor M. Dunietz
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague 182 23, Czech Republic
| | - Lubomír Rulíšek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10, Praha 6, Czech Republic
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
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2
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Motlová L, Šnajdr I, Kutil Z, Andris E, Ptáček J, Novotná A, Nováková Z, Havlínová B, Tueckmantel W, Dráberová H, Majer P, Schutkowski M, Kozikowski A, Rulíšek L, Bařinka C. Comprehensive Mechanistic View of the Hydrolysis of Oxadiazole-Based Inhibitors by Histone Deacetylase 6 (HDAC6). ACS Chem Biol 2023. [PMID: 37392419 PMCID: PMC10367051 DOI: 10.1021/acschembio.3c00212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/03/2023]
Abstract
Histone deacetylase (HDAC) inhibitors used in the clinic typically contain a hydroxamate zinc-binding group (ZBG). However, more recent work has shown that the use of alternative ZBGs, and, in particular, the heterocyclic oxadiazoles, can confer higher isoenzyme selectivity and more favorable ADMET profiles. Herein, we report on the synthesis and biochemical, crystallographic, and computational characterization of a series of oxadiazole-based inhibitors selectively targeting the HDAC6 isoform. Surprisingly, but in line with a very recent finding reported in the literature, a crystal structure of the HDAC6/inhibitor complex revealed that hydrolysis of the oxadiazole ring transforms the parent oxadiazole into an acylhydrazide through a sequence of two hydrolytic steps. An identical cleavage pattern was also observed both in vitro using the purified HDAC6 enzyme as well as in cellular systems. By employing advanced quantum and molecular mechanics (QM/MM) and QM calculations, we elucidated the mechanistic details of the two hydrolytic steps to obtain a comprehensive mechanistic view of the double hydrolysis of the oxadiazole ring. This was achieved by fully characterizing the reaction coordinate, including identification of the structures of all intermediates and transition states, together with calculations of their respective activation (free) energies. In addition, we ruled out several (intuitively) competing pathways. The computed data (ΔG‡ ≈ 21 kcal·mol-1 for the rate-determining step of the overall dual hydrolysis) are in very good agreement with the experimentally determined rate constants, which a posteriori supports the proposed reaction mechanism. We also clearly (and quantitatively) explain the role of the -CF3 or -CHF2 substituent on the oxadiazole ring, which is a prerequisite for hydrolysis to occur. Overall, our data provide compelling evidence that the oxadiazole warheads can be efficiently transformed within the active sites of target metallohydrolases to afford reaction products possessing distinct selectivity and inhibition profiles.
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Affiliation(s)
- Lucia Motlová
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Ivan Šnajdr
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Zsófia Kutil
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Erik Andris
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Jakub Ptáček
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Adéla Novotná
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Zora Nováková
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Barbora Havlínová
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Werner Tueckmantel
- StarWise Therapeutics LLC, University Research Park, Inc., Madison, Wisconsin 53719, United States
| | - Helena Dráberová
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Pavel Majer
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Mike Schutkowski
- Department of Enzymology, Charles Tanford Protein Center, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, 06120 Halle, Germany
| | - Alan Kozikowski
- StarWise Therapeutics LLC, University Research Park, Inc., Madison, Wisconsin 53719, United States
| | - Lubomír Rulíšek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Cyril Bařinka
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
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3
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Pirro F, La Gatta S, Arrigoni F, Famulari A, Maglio O, Del Vecchio P, Chiesa M, De Gioia L, Bertini L, Chino M, Nastri F, Lombardi A. A De Novo-Designed Type 3 Copper Protein Tunes Catechol Substrate Recognition and Reactivity. Angew Chem Int Ed Engl 2023; 62:e202211552. [PMID: 36334012 DOI: 10.1002/anie.202211552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Indexed: 11/07/2022]
Abstract
De novo metalloprotein design is a remarkable approach to shape protein scaffolds toward specific functions. Here, we report the design and characterization of Due Rame 1 (DR1), a de novo designed protein housing a di-copper site and mimicking the Type 3 (T3) copper-containing polyphenol oxidases (PPOs). To achieve this goal, we hierarchically designed the first and the second di-metal coordination spheres to engineer the di-copper site into a simple four-helix bundle scaffold. Spectroscopic, thermodynamic, and functional characterization revealed that DR1 recapitulates the T3 copper site, supporting different copper redox states, and being active in the O2 -dependent oxidation of catechols to o-quinones. Careful design of the residues lining the substrate access site endows DR1 with substrate recognition, as revealed by Hammet analysis and computational studies on substituted catechols. This study represents a premier example in the construction of a functional T3 copper site into a designed four-helix bundle protein.
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Affiliation(s)
- Fabio Pirro
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126, Naples, Italy
| | - Salvatore La Gatta
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126, Naples, Italy
| | - Federica Arrigoni
- Department of Biotechnology and Biosciences, University of Milan-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Antonino Famulari
- Department of Chemistry, University of Torino, Via Giuria 9, 10125, Torino, Italy.,Department of Condensed Matter Physics, University of of Zaragoza, Calle Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Ornella Maglio
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126, Naples, Italy.,Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), Via Pietro Castellino 111, 80131, Napoli, Italy
| | - Pompea Del Vecchio
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126, Naples, Italy
| | - Mario Chiesa
- Department of Chemistry, University of Torino, Via Giuria 9, 10125, Torino, Italy
| | - Luca De Gioia
- Department of Biotechnology and Biosciences, University of Milan-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Luca Bertini
- Department of Biotechnology and Biosciences, University of Milan-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Marco Chino
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126, Naples, Italy
| | - Flavia Nastri
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126, Naples, Italy
| | - Angela Lombardi
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126, Naples, Italy
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Kipouros I, Solomon EI. New mechanistic insights into coupled binuclear copper monooxygenases from the recent elucidation of the ternary intermediate of tyrosinase. FEBS Lett 2023; 597:65-78. [PMID: 36178078 PMCID: PMC9839588 DOI: 10.1002/1873-3468.14503] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 01/17/2023]
Abstract
Tyrosinase is the most predominant member of the coupled binuclear copper (CBC) protein family. The recent trapping and spectroscopic definition of the elusive catalytic ternary intermediate (enzyme/O2 /monophenol) of tyrosinase dictates a monooxygenation mechanism that revises previous proposals and involves cleavage of the μ-η2 :η2 -peroxide dicopper(II) O-O bond to accept the phenolic proton, followed by monophenolate coordination to copper concomitant with aromatic hydroxylation by the non-protonated μ-oxo. Here, we compare and contrast previously proposed and current mechanistic models for monophenol monooxygenation of tyrosinase. Next, we discuss how these recent insights provide new opportunities towards uncovering structure-function relationships in CBC enzymes, as well as understanding fundamental principles for O2 activation and reactivity by bioinorganic active sites.
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Affiliation(s)
| | - Edward I Solomon
- Department of Chemistry, Stanford University, CA, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, CA, USA
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5
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Kipouros I, Stańczak A, Ginsbach JW, Andrikopoulos PC, Rulíšek L, Solomon EI. Elucidation of the tyrosinase/O 2/monophenol ternary intermediate that dictates the monooxygenation mechanism in melanin biosynthesis. Proc Natl Acad Sci U S A 2022; 119:e2205619119. [PMID: 35939688 PMCID: PMC9389030 DOI: 10.1073/pnas.2205619119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 07/05/2022] [Indexed: 11/18/2022] Open
Abstract
Melanins are highly conjugated biopolymer pigments that provide photoprotection in a wide array of organisms, from bacteria to humans. The rate-limiting step in melanin biosynthesis, which is the ortho-hydroxylation of the amino acid L-tyrosine to L-DOPA, is catalyzed by the ubiquitous enzyme tyrosinase (Ty). Ty contains a coupled binuclear copper active site that binds O2 to form a μ:η2:η2-peroxide dicopper(II) intermediate (oxy-Ty), capable of performing the regioselective monooxygenation of para-substituted monophenols to catechols. The mechanism of this critical monooxygenation reaction remains poorly understood despite extensive efforts. In this study, we have employed a combination of spectroscopic, kinetic, and computational methods to trap and characterize the elusive catalytic ternary intermediate (Ty/O2/monophenol) under single-turnover conditions and obtain molecular-level mechanistic insights into its monooxygenation reactivity. Our experimental results, coupled with quantum-mechanics/molecular-mechanics calculations, reveal that the monophenol substrate docks in the active-site pocket of oxy-Ty fully protonated, without coordination to a copper or cleavage of the μ:η2:η2-peroxide O-O bond. Formation of this ternary intermediate involves the displacement of active-site water molecules by the substrate and replacement of their H bonds to the μ:η2:η2-peroxide by a single H bond from the substrate hydroxyl group. This H-bonding interaction in the ternary intermediate enables the unprecedented monooxygenation mechanism, where the μ-η2:η2-peroxide O-O bond is cleaved to accept the phenolic proton, followed by substrate phenolate coordination to a copper site concomitant with its aromatic ortho-hydroxylation by the nonprotonated μ-oxo. This study provides insights into O2 activation and reactivity by coupled binuclear copper active sites with fundamental implications in biocatalysis.
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Affiliation(s)
- Ioannis Kipouros
- Department of Chemistry, Stanford University, Stanford, CA 94305
| | - Agnieszka Stańczak
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10, Prague 6, Czech Republic
- Faculty of Science, Charles University, 128 00 Prague 2, Czech Republic
| | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA 94305
| | - Prokopis C. Andrikopoulos
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10, Prague 6, Czech Republic
| | - Lubomír Rulíšek
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10, Prague 6, Czech Republic
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, CA 94305
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025
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