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De Novo Design of a Self-Assembled Artificial Copper Peptide that Activates and Reduces Peroxide.

ABSTRACT: Copper-containing metalloenzymes constitute a major class of proteins which catalyze a myriad of reactions in nature. Inspired by the structural and functional characteristics of this unique class of metalloenzymes, we report the conception, design, characterization, and functional studies of a de novo artificial copper peptide (ArCuP) within a trimeric self-assembled polypeptide scaffold that activates and reduces peroxide. Using a first principles approach, the ArCuP was designed to coordinate one Cu via three His residues introduced at an a site of the peptide scaffold. X-ray crystallographic, UV-vis and EPR data demonstrate that Cu binds via the N_ε atoms of His forming a T2Cu environment. When reacted with hydrogen peroxide, the putative copper-hydroperoxo species is formed where a reductive priming step accelerates the rate of its formation and reduction. Mass spectrometry was used to identify specific residues undergoing oxidative modification, which showed His oxidation only in the reduced state. The redox behavior of the ArCuP was elucidated by protein film voltammetry. Detailed characterization of the electrocatalytic behavior of the ArCuP led us to determine the catalytic parameters (K_M, k_cat), which established the peroxidase activity of the ArCuP. Combined spectroscopic and electrochemical data showed a pH-dependence on the reactivity, which was optimum at pH 7.5.

SUBMITTER: Mitra S

PROVIDER: S-EPMC9524465 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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De Novo Design of a Self-Assembled Artificial Copper Peptide that Activates and Reduces Peroxide.

Mitra Suchitra S Mitra Suchitra S Prakash Divyansh D Rajabimoghadam Khashayar K Wawrzak Zdzislaw Z Prasad Pallavi P Wu Tong T Misra Sandeep K SK Sharp Joshua S JS Garcia-Bosch Isaac I Chakraborty Saumen S

ACS catalysis 20210803 16

Copper-containing metalloenzymes constitute a major class of proteins which catalyze a myriad of reactions in nature. Inspired by the structural and functional characteristics of this unique class of metalloenzymes, we report the conception, design, characterization, and functional studies of a de novo artificial copper peptide (ArCuP) within a trimeric self-assembled polypeptide scaffold that activates and reduces peroxide. Using a first principles approach, the ArCuP was designed to coordinate ...[more]

PMID: 36188417

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Project description:Using de novo protein design, we incorporated a copper metal binding site within the three-helix bundle α3D (Walsh et al. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 5486-5491) to assess whether a cupredoxin center within an α-helical domain could mimic the spectroscopic, structural, and redox features of native type-1 copper (CuT1) proteins. We aimed to determine whether a CuT1 center could be realized in a markedly different scaffold rather than the native β-barrel fold and whether the characteristic short Cu-S bond (2.1-2.2 Å) and positive reduction potentials could be decoupled from the spectroscopic properties (ε600 nm = 5000 M(-1) cm(-1)) of such centers. We incorporated 2HisCys(Met) residues in three distinct α3D designs designated core (CR), chelate (CH), and chelate-core (ChC). XAS analysis revealed a coordination environment similar to reduced CuT1 proteins, producing Cu-S(Cys) bonds ranging from 2.16 to 2.23 Å and Cu-N(His) bond distances of 1.92-1.99 Å. However, Cu(II) binding to the CR and CH constructs resulted in tetragonal type-2 copper-like species, displaying an intense absorption band between 380 and 400 nm (>1500 M(-1) cm(-1)) and A|| values of (150-185) × 10(-4) cm(-4). The ChC construct, which possesses a metal-binding site deeper in its helical bundle, yielded a CuT1-like brown copper species, with two absorption bands at 401 (4429 M(-1) cm(-1)) and 499 (2020 M(-1) cm(-1)) nm and an A|| value ∼30 × 10(-4) cm(-4) greater than its native counterparts. Electrochemical studies demonstrated reduction potentials of +360 to +460 mV (vs NHE), which are within the observed range for azurin and plastocyanin. These observations showed that the designed metal binding sites lacked the necessary rigidity to enforce the appropriate structural constraints for a Cu(II) chromophore (EPR and UV-vis); however, the Cu(I) structural environment and the high positive potential of CuT1 centers were recapitulated within the α-helical bundle of α3D.

Project description:Histones are small proteins critical to the efficient packaging of DNA in the nucleus. DNA–protein complexes, known as nucleosomes, are formed when the DNA winds itself around the surface of the histones. The methylation of histone residues by enhancer of zeste homolog 2 (EZH2) maintains gene repression over successive cell generations. Overexpression of EZH2 can silence important tumor suppressor genes leading to increased invasiveness of many types of cancers. This makes the inhibition of EZH2 an important target in the development of cancer therapeutics. We employed a three-stage computational de novo peptide design method to design inhibitory peptides of EZH2. The method consists of a sequence selection stage and two validation stages for fold specificity and approximate binding affinity. The sequence selection stage consists of an integer linear optimization model that was solved to produce a rank-ordered list of amino acid sequences with increased stability in the bound peptide-EZH2 structure. These sequences were validated through the calculation of the fold specificity and approximate binding affinity of the designed peptides. Here we report the discovery of novel EZH2 inhibitory peptides using the de novo peptide design method. The computationally discovered peptides were experimentally validated in vitro using dose titrations and mechanism of action enzymatic assays. The peptide with the highest in vitro response, SQ037, was validated in nucleo using quantitative mass spectrometry-based proteomics. This peptide had an IC50 of 13.5 mM, demonstrated greater potency as an inhibitor when compared to the native and K27A mutant control peptides, and demonstrated competitive inhibition versus the peptide substrate. Additionally, this peptide demonstrated high specificity to the EZH2 target in comparison to other histone methyltransferases. The validated peptides are the first computationally designed peptides that directly inhibit EZH2. These inhibitors should prove useful for further chromatin biology investigations.

Dataset Information

De Novo Design of a Self-Assembled Artificial Copper Peptide that Activates and Reduces Peroxide.

Publications

De Novo Design of a Self-Assembled Artificial Copper Peptide that Activates and Reduces Peroxide.

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