1
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Tóth A, Sajdik K, Gyurcsik B, Nafaee ZH, Wéber E, Kele Z, Christensen NJ, Schell J, Correia JG, Sigfridsson Clauss KGV, Pittkowski RK, Thulstrup PW, Hemmingsen L, Jancsó A. As III Selectively Induces a Disorder-to-Order Transition in the Metalloid Binding Region of the AfArsR Protein. J Am Chem Soc 2024; 146:17009-17022. [PMID: 38820242 DOI: 10.1021/jacs.3c11665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2024]
Abstract
Arsenic is highly toxic and a significant threat to human health, but certain bacteria have developed defense mechanisms initiated by AsIII binding to AsIII-sensing proteins of the ArsR family. The transcriptional regulator AfArsR responds to AsIII and SbIII by coordinating the metalloids with three cysteines, located in a short sequence of the same monomer chain. Here, we characterize the binding of AsIII and HgII to a model peptide encompassing this fragment of the protein via solution equilibrium and spectroscopic/spectrometric techniques (pH potentiometry, UV, CD, NMR, PAC, EXAFS, and ESI-MS) combined with DFT calculations and MD simulations. Coordination of AsIII changes the peptide structure from a random-coil to a well-defined structure of the complex. A trigonal pyramidal AsS3 binding site is formed with almost exactly the same structure as observed in the crystal structure of the native protein, implying that the peptide possesses all of the features required to mimic the AsIII recognition and response selectivity of AfArsR. Contrary to this, binding of HgII to the peptide does not lead to a well-defined structure of the peptide, and the atoms near the metal binding site are displaced and reoriented in the HgII model. Our model study suggests that structural organization of the metal site by the inducer ion is a key element in the mechanism of the metalloid-selective recognition of this protein.
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Affiliation(s)
- Annamária Tóth
- Department of Molecular and Analytical Chemistry, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary
| | - Kadosa Sajdik
- Department of Molecular and Analytical Chemistry, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary
| | - Béla Gyurcsik
- Department of Molecular and Analytical Chemistry, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary
| | - Zeyad H Nafaee
- Department of Molecular and Analytical Chemistry, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary
| | - Edit Wéber
- Department of Medical Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
- HUN-REN-SZTE Biomimetic Systems Research Group, Dóm tér 8, H-6720 Szeged, Hungary
| | - Zoltan Kele
- Department of Medical Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
| | - Niels Johan Christensen
- Department of Chemistry, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Juliana Schell
- Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141 Essen, Germany
- European Organization for Nuclear Research (CERN), CH-1211 Geneva, Switzerland
| | - Joao Guilherme Correia
- Centro de Cięncias e Tecnologias Nucleares, Departamento de Engenharia e Cięncias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal
- European Organization for Nuclear Research (CERN), CH-1211 Geneva, Switzerland
| | | | - Rebecca K Pittkowski
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Kobenhavn Ø, Denmark
| | - Peter Waaben Thulstrup
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Kobenhavn Ø, Denmark
| | - Lars Hemmingsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Kobenhavn Ø, Denmark
| | - Attila Jancsó
- Department of Molecular and Analytical Chemistry, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary
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2
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Borghesani V, Zastrow ML, Tolbert AE, Deb A, Penner-Hahn JE, Pecoraro VL. Co(II) Substitution Enhances the Esterase Activity of a de Novo Designed Zn(II) Carbonic Anhydrase. Chemistry 2024; 30:e202304367. [PMID: 38377169 PMCID: PMC11045307 DOI: 10.1002/chem.202304367] [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] [Received: 12/29/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 02/22/2024]
Abstract
Carbonic Anhydrases (CAs) have been a target for de novo protein designers due to the simplicity of the active site and rapid rate of the reaction. The first reported mimic contained a Zn(II) bound to three histidine imidazole nitrogens and an exogenous water molecule, hence closely mimicking the native enzymes' first coordination sphere. Co(II) has served as an alternative metal to interrogate CAs due to its d7 electronic configuration for more detailed solution characterization. We present here the Co(II) substituted [Co(II)(H2O/OH-)]N(TRIL2WL23H)3 n+ that behaves similarly to native Co(II) substituted human-CAs. Like the Zn(II) analogue, the cobalt-derivative at slightly basic pH is incapable of hydrolyzing p-nitrophenylacetate (pNPA); however, as the pH is increased a significant activity develops, which at pH values above 10 eventually yields a catalytic efficiency that exceeds that of the [Zn(II)(OH-)]N(TRIL2WL23H)3 + peptide complex. X-ray absorption analysis is consistent with an octahedral species at pH 7.5 that converts to a 5-coordinate species by pH 11. UV-vis spectroscopy can monitor this transition, giving a pKa for the conversion of 10.3. We assign this conversion to the formation of a 5-coordinate Co(II)(Nimid)3(OH)(H2O) species. The pH dependent kinetic analysis indicates the maximal rate (kcat), and thus the catalytic efficiency (kcat/Km), follow the same pH profile as the spectroscopic conversion to the pentacoordinate species. This correlation suggests that the chemically irreversible ester hydrolysis corresponds to the rate determining process.
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Affiliation(s)
- Valentina Borghesani
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI-48109-1055, United States
- Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle, Scienze 11A, 43124, Parma, Italy
| | - Melissa L Zastrow
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI-48109-1055, United States
- Department of Chemistry, University of Houston, 3585 Cullen Blvd, Houston, TX-77204, United States
| | - Audrey E Tolbert
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI-48109-1055, United States
| | - Aniruddha Deb
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI-48109-1055, United States
| | - James E Penner-Hahn
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI-48109-1055, United States
| | - Vincent L Pecoraro
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI-48109-1055, United States
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3
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Chen K, Cheng X, Xue S, Chen J, Zhang X, Qi Y, Chen R, Zhang Y, Wang H, Li W, Cheng G, Huang Y, Xiong Y, Chen L, Mu C, Gu M. Albumin conjugation promotes arsenic trioxide transport through alkaline phosphatase-associated transcytosis in MUC4 wildtype pancreatic cancer cells. Int J Biol Macromol 2024; 257:128756. [PMID: 38092098 DOI: 10.1016/j.ijbiomac.2023.128756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 12/08/2023] [Accepted: 12/09/2023] [Indexed: 12/17/2023]
Abstract
Pancreatic cancer (PC) has a poor prognosis due to chemotherapy resistance and unfavorable drug transportation. Albumin conjugates are commonly used as drug carriers to overcome these obstacles. However, membrane-bound glycoprotein mucin 4 (MUC4) has emerged as a promising biomarker among the genetic mutations affecting albumin conjugates therapeutic window. Human serum albumin-conjugated arsenic trioxide (HSA-ATO) has shown potential in treating solid tumors but is limited in PC therapy due to unclear targets and mechanisms. This study investigated the transport mechanisms and therapeutic efficacy of HSA-ATO in PC cells with different MUC4 mutation statuses. Results revealed improved penetration of ATO into PC tumors through conjugated with HSA. However, MUC4 mutation significantly affected treatment sensitivity and HSA-ATO uptake both in vitro and in vivo. Mutant MUC4 cells exhibited over ten times higher IC50 for HSA-ATO and approximately half the uptake compared to wildtype cells. Further research demonstrated that ALPL activation by HSA-ATO enhanced transcytosis in wildtype MUC4 PC cells but not in mutant MUC4 cells, leading to impaired uptake and weaker antitumor effects. Reprogramming the transport process holds potential for enhancing albumin conjugate efficacy in PC patients with different MUC4 mutation statuses, paving the way for stratified treatment using these delivery vehicles.
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Affiliation(s)
- Kaidi Chen
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China
| | - Xiao Cheng
- Huzhou Institute for Food and Drug Control, Huzhou 313000, PR China
| | - Shuai Xue
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China
| | - Junyan Chen
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China
| | - Xu Zhang
- Zhejiang Heze Pharmaceutical Technology Co., Ltd., Hangzhou 310018, Zhejiang, PR China
| | - Yuwei Qi
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China
| | - Rong Chen
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China
| | - Yan Zhang
- Department of Pharmacy, Hangzhou Red Cross Hospital, Hangzhou 310003, Zhejiang, PR China
| | - Hangjie Wang
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China
| | - Wei Li
- Academy of Chinese Medical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China
| | - Guilin Cheng
- Department of Pharmacy, Hangzhou Red Cross Hospital, Hangzhou 310003, Zhejiang, PR China
| | - Ye Huang
- Department of Pharmacy, Zhejiang Provincial Dermatology Hospital, Huzhou 313200, Zhejiang, PR China
| | - Yang Xiong
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China; Department of Pharmacy, Hangzhou Red Cross Hospital, Hangzhou 310003, Zhejiang, PR China
| | - Liping Chen
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325001, Zhejiang, PR China; School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, Jiangsu, PR China.
| | - Chaofeng Mu
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China.
| | - Mancang Gu
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China; Academy of Chinese Medical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang, PR China.
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4
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Gurusaran M, Biemans JJ, Wood CW, Davies OR. Molecular insights into LINC complex architecture through the crystal structure of a luminal trimeric coiled-coil domain of SUN1. Front Cell Dev Biol 2023; 11:1144277. [PMID: 37416798 PMCID: PMC10320395 DOI: 10.3389/fcell.2023.1144277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 06/09/2023] [Indexed: 07/08/2023] Open
Abstract
The LINC complex, consisting of interacting SUN and KASH proteins, mechanically couples nuclear contents to the cytoskeleton. In meiosis, the LINC complex transmits microtubule-generated forces to chromosome ends, driving the rapid chromosome movements that are necessary for synapsis and crossing over. In somatic cells, it defines nuclear shape and positioning, and has a number of specialised roles, including hearing. Here, we report the X-ray crystal structure of a coiled-coiled domain of SUN1's luminal region, providing an architectural foundation for how SUN1 traverses the nuclear lumen, from the inner nuclear membrane to its interaction with KASH proteins at the outer nuclear membrane. In combination with light and X-ray scattering, molecular dynamics and structure-directed modelling, we present a model of SUN1's entire luminal region. This model highlights inherent flexibility between structured domains, and raises the possibility that domain-swap interactions may establish a LINC complex network for the coordinated transmission of cytoskeletal forces.
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Affiliation(s)
- Manickam Gurusaran
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Jelle J. Biemans
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Christopher W. Wood
- Institute of Quantitative Biology, Biochemistry and Biotechnology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Owen R. Davies
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
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5
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Selvan D, Chakraborty S. A De Novo Designed Trimeric Metalloprotein as a Ni p Model of the Acetyl-CoA Synthase. Int J Mol Sci 2023; 24:10317. [PMID: 37373464 DOI: 10.3390/ijms241210317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/30/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023] Open
Abstract
We present a Nip site model of acetyl coenzyme-A synthase (ACS) within a de novo-designed trimer peptide that self-assembles to produce a homoleptic Ni(Cys)3 binding motif. Spectroscopic and kinetic studies of ligand binding demonstrate that Ni binding stabilizes the peptide assembly and produces a terminal NiI-CO complex. When the CO-bound state is reacted with a methyl donor, a new species is quickly produced with new spectral features. While the metal-bound CO is albeit unactivated, the presence of the methyl donor produces an activated metal-CO complex. Selective outer sphere steric modifications demonstrate that the physical properties of the ligand-bound states are altered differently depending on the location of the steric modification above or below the Ni site.
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Affiliation(s)
- Dhanashree Selvan
- Department of Chemistry and Biochemistry, University of Mississippi, Coulter Hall, Oxford, MS 38677, USA
| | - Saumen Chakraborty
- Department of Chemistry and Biochemistry, University of Mississippi, Coulter Hall, Oxford, MS 38677, USA
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6
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Szekeres L, Maldivi P, Lebrun C, Gateau C, Mesterházy E, Delangle P, Jancsó A. Tristhiolato Pseudopeptides Bind Arsenic(III) in an AsS 3 Coordination Environment Imitating Metalloid Binding Sites in Proteins. Inorg Chem 2023; 62:6817-6824. [PMID: 37071818 PMCID: PMC10155180 DOI: 10.1021/acs.inorgchem.3c00563] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Indexed: 04/20/2023]
Abstract
The AsIII binding of two NTA-based tripodal pseudopeptides, possessing three cysteine (ligand L1) or d-penicillamine residues (ligand L2) as potential coordinating groups for soft semimetals or metal ions, was studied by experimental (UV, CD, NMR, and ESI-MS) and theoretical (DFT) methods. All of the experimental data, obtained with the variation of the AsIII:ligand concentration ratios or pH values in some instances, evidence the exclusive formation of species with an AsS3-type coordination mode. The UV-monitored titration of the ligands with arsenous acid at pH = 7.0 provided an absorbance data set that allowed for the determination of apparent stability constants of the forming species. The obtained stabilities (logK' = 5.26 (AsL1) and logK' = 3.04 (AsL2)) reflect high affinities, especially for the sterically less restricted cysteine derivative. DFT calculated structures correlate well with the spectroscopic results and, in line with the 1H NMR data, indicate a preference for the all-endo conformers resembling the AsIII environment at the semimetal binding sites in various metalloproteins.
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Affiliation(s)
- Levente
I. Szekeres
- Department
of Inorganic and Analytical Chemistry, University
of Szeged, Dóm tér 7, Szeged H-6720, Hungary
| | - Pascale Maldivi
- CEA,
CNRS, Grenoble INP, IRIG, SyMMES, Universite
Grenoble Alpes, Grenoble 38000, France
| | - Colette Lebrun
- CEA,
CNRS, Grenoble INP, IRIG, SyMMES, Universite
Grenoble Alpes, Grenoble 38000, France
| | - Christelle Gateau
- CEA,
CNRS, Grenoble INP, IRIG, SyMMES, Universite
Grenoble Alpes, Grenoble 38000, France
| | - Edit Mesterházy
- Department
of Inorganic and Analytical Chemistry, University
of Szeged, Dóm tér 7, Szeged H-6720, Hungary
- CEA,
CNRS, Grenoble INP, IRIG, SyMMES, Universite
Grenoble Alpes, Grenoble 38000, France
| | - Pascale Delangle
- CEA,
CNRS, Grenoble INP, IRIG, SyMMES, Universite
Grenoble Alpes, Grenoble 38000, France
| | - Attila Jancsó
- Department
of Inorganic and Analytical Chemistry, University
of Szeged, Dóm tér 7, Szeged H-6720, Hungary
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7
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Li J, Cui M, Zhao J, Wang J, Fang X. A self-amplifying plasmid based ultrasensitive biosensor for the detection of As(Ⅲ) in water. Biosens Bioelectron 2022; 221:114937. [DOI: 10.1016/j.bios.2022.114937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/16/2022] [Accepted: 11/18/2022] [Indexed: 11/24/2022]
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8
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Shih PY, Fang YL, Shankar S, Lee SP, Hu HT, Chen H, Wang TF, Hsia KC, Hsueh YP. Phase separation and zinc-induced transition modulate synaptic distribution and association of autism-linked CTTNBP2 and SHANK3. Nat Commun 2022; 13:2664. [PMID: 35562389 PMCID: PMC9106668 DOI: 10.1038/s41467-022-30353-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 04/26/2022] [Indexed: 11/09/2022] Open
Abstract
Many synaptic proteins form biological condensates via liquid-liquid phase separation (LLPS). Synaptopathy, a key feature of autism spectrum disorders (ASD), is likely relevant to the impaired phase separation and/or transition of ASD-linked synaptic proteins. Here, we report that LLPS and zinc-induced liquid-to-gel phase transition regulate the synaptic distribution and protein-protein interaction of cortactin-binding protein 2 (CTTNBP2), an ASD-linked protein. CTTNBP2 forms self-assembled condensates through its C-terminal intrinsically disordered region and facilitates SHANK3 co-condensation at dendritic spines. Zinc binds the N-terminal coiled-coil region of CTTNBP2, promoting higher-order assemblies. Consequently, it leads to reduce CTTNBP2 mobility and enhance the stability and synaptic retention of CTTNBP2 condensates. Moreover, ASD-linked mutations alter condensate formation and synaptic retention of CTTNBP2 and impair mouse social behaviors, which are all ameliorated by zinc supplementation. Our study suggests the relevance of condensate formation and zinc-induced phase transition to the synaptic distribution and function of ASD-linked proteins. Autism impacts synapses. This study reports that autism-linked mutations of CTTNBP2 regulate phase separation to control synaptic enrichment of that protein. A zinc-induced liquid-to-gel transition improves synaptic retention of CTTNBP2 and SHANK3.
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Affiliation(s)
- Pu-Yun Shih
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC.,Department of Neurology, University of California San Francisco, San Francisco, USA
| | - Yu-Lun Fang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC.,Department and Graduate Institute of Biochemistry, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Sahana Shankar
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC.,Molecular and Cell Biology, Taiwan International Graduate Program, Institute of Molecular Biology, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Sue-Ping Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC
| | - Hsiao-Tang Hu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC
| | - Hsin Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC.,Undergraduate Program in Neuroscience, John Hopkins University, Baltimore, USA
| | - Ting-Fang Wang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC.,Molecular and Cell Biology, Taiwan International Graduate Program, Institute of Molecular Biology, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Kuo-Chiang Hsia
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC. .,Molecular and Cell Biology, Taiwan International Graduate Program, Institute of Molecular Biology, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC.
| | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC. .,Molecular and Cell Biology, Taiwan International Graduate Program, Institute of Molecular Biology, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC.
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9
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Pinter TB, Ervin CS, Deb A, Penner-Hahn JE, Pecoraro VL. Cu(I) Binding to Designed Proteins Reveals a Putative Copper Binding Site of the Human Line1 Retrotransposon Protein ORF1p. Inorg Chem 2022; 61:5084-5091. [PMID: 35286080 PMCID: PMC10754372 DOI: 10.1021/acs.inorgchem.2c00057] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Long interspersed nuclear elements-1 (L1) are autonomous retrotransposons that encode two proteins in different open reading frames (ORF1 and ORF2). The ORF1p, which may be an RNA binding and chaperone protein, contains a three-stranded coiled coil (3SCC) domain that facilitates the formation of the biologically active homotrimer. This 3SCC domain is composed of seven amino acid (heptad) repeats as found in native and designed peptides and a stammer that modifies the helical structure. Cysteine residues occur at three hydrophobic positions (2 a and 1 d sites) within this domain. We recently showed that the cysteine layers in ORF1p and model de novo designed peptides bind the toxic metalloid lead(II) with high affinities, a feature that had not been previously recognized. However, there is little understanding of how essential metal ions might interact with this metal binding domain. We have, therefore, investigated the copper(I) binding properties of analogous de novo designed 3SCCs that contain cysteine layers within the hydrophobic core. The results from UV-visible and X-ray absorption spectroscopy show that these designed peptides bind Cu(I) with high affinity in a pH-dependent manner. At pH 9, monomeric trigonal planar Cu(I)S3 centers are formed with 1 equiv of metal, while dinuclear centers form with a second equivalent of metal. At physiologic pH conditions, the dinuclear center forms cooperatively. These data suggest that ORF1p is capable of binding two copper ions to its tris(cysteine) layers. This has major implications for ORF1p coiled coil domain stability and dynamics, ultimately potentially impacting the resulting biological activity.
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Affiliation(s)
- Tyler B.J. Pinter
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- These authors contributed equally to this work
| | - Catherine S. Ervin
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- These authors contributed equally to this work
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - James E. Penner-Hahn
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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10
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Mitra S, Prakash D, Rajabimoghadam K, Wawrzak Z, Prasad P, Wu T, Misra SK, Sharp JS, Garcia-Bosch I, Chakraborty S. De Novo Design of a Self-Assembled Artificial Copper Peptide that Activates and Reduces Peroxide. ACS Catal 2021; 11:10267-10278. [DOI: 10.1021/acscatal.1c02132] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Suchitra Mitra
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Divyansh Prakash
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | | | - Zdzislaw Wawrzak
- Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, United States
| | - Pallavi Prasad
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Tong Wu
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Sandeep K. Misra
- Department of Biomolecular Sciences, University of Mississippi, University, Mississippi 38677, United States
| | - Joshua S. Sharp
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
- Department of Biomolecular Sciences, University of Mississippi, University, Mississippi 38677, United States
| | - Isaac Garcia-Bosch
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Saumen Chakraborty
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
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11
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Slope LN, Hill MG, Smith CF, Teare P, de Cogan FJ, Britton MM, Peacock AFA. Tuning coordination chemistry through the second sphere in designed metallocoiled coils. Chem Commun (Camb) 2020; 56:3729-3732. [PMID: 32129331 DOI: 10.1039/c9cc08189e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The metal hydration state within a designed coiled coil can be progressively tuned across the full integer range (3 → 0 aqua ligands), by careful choice of a second sphere terminal residue, including the lesser used Trp. Potential implications include a four-fold change in MRI relaxivity when applied to lanthanide coiled coils.
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Affiliation(s)
- Louise N Slope
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Michael G Hill
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Catherine F Smith
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Paul Teare
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Felicity J de Cogan
- Institute of Microbiology and Infection, University of Birmingham, B15 2TT, UK
| | - Melanie M Britton
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Anna F A Peacock
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
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12
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Duan J, Liu B, Liu J. Interactions between gold, thiol and As(iii) for colorimetric sensing. Analyst 2020; 145:5166-5173. [DOI: 10.1039/d0an00946f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Arsenite cannot crosslink glutathione-capped gold nanoparticles but a high concentration of arsenite can displace adsorbed glutathione, indicating that any two species from gold, thiol and arsenite can react.
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Affiliation(s)
- Junling Duan
- College of Chemistry and Material Science
- Shandong Agricultural University
- Tai'an
- P.R. China
- Department of Chemistry
| | - Biwu Liu
- Department of Chemistry
- Waterloo Institute for Nanotechnology
- University of Waterloo
- Waterloo
- Canada
| | - Juewen Liu
- Department of Chemistry
- Waterloo Institute for Nanotechnology
- University of Waterloo
- Waterloo
- Canada
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13
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Soleja N, Manzoor O, Khan P, Mohsin M. Engineering genetically encoded FRET-based nanosensors for real time display of arsenic (As 3+) dynamics in living cells. Sci Rep 2019; 9:11240. [PMID: 31375744 PMCID: PMC6677752 DOI: 10.1038/s41598-019-47682-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 07/12/2019] [Indexed: 02/07/2023] Open
Abstract
Arsenic poisoning has been a major concern that causes severe toxicological damages. Therefore, intricate and inclusive understanding of arsenic flux rates is required to ascertain the cellular concentration and establish the carcinogenetic mechanism of this toxicant at real time. The lack of sufficiently sensitive sensing systems has hampered research in this area. In this study, we constructed a fluorescent resonance energy transfer (FRET)-based nanosensor, named SenALiB (Sensor for Arsenic Linked Blackfoot disease) which contains a metalloregulatory arsenic-binding protein (ArsR) as the As3+ sensing element inserted between the FRET pair enhanced cyan fluorescent protein (ECFP) and Venus. SenALiB takes advantage of the ratiometic FRET readout which measures arsenic with high specificity and selectivity. SenALiB offers rapid detection response, is stable to pH changes and provides highly accurate, real-time optical readout in cell-based assays. SenALiB-676n with a binding constant (Kd) of 0.676 × 10−6 M is the most efficient affinity mutant and can be a versatile tool for dynamic measurement of arsenic concentration in both prokaryotes and eukaryotes in vivo in a non-invasive manner.
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Affiliation(s)
- Neha Soleja
- Department of Biosciences, Jamia Millia Islamia, New Delhi, 110025, India
| | - Ovais Manzoor
- Department of Biosciences, Jamia Millia Islamia, New Delhi, 110025, India
| | - Parvez Khan
- Centre for Interdisciplinary Research in Basic Science, Jamia Millia Islamia, New Delhi, 110025, India
| | - Mohd Mohsin
- Department of Biosciences, Jamia Millia Islamia, New Delhi, 110025, India.
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14
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Koebke KJ, Pecoraro VL. Noncoded Amino Acids in de Novo Metalloprotein Design: Controlling Coordination Number and Catalysis. Acc Chem Res 2019; 52:1160-1167. [PMID: 30933479 DOI: 10.1021/acs.accounts.9b00032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The relationship between structure and function has long been one of the major points of investigation in Biophysics. Understanding how much, or how little, of a protein's often complicated structure is necessary for its function can lead to directed therapeutic strategies and would allow one to design proteins for specific desired functions. Studying protein function by de novo design builds the functionality from the ground up in a completely unrelated and noncoded protein scaffold. Our lab has used this strategy to study heavy and transition metal binding within the TRI family of three stranded coiled coil (3SCC) constructs to understand coordination geometry and metalloenzyme catalytic control within a protein environment. These peptides contain hydrophobic layers within the interior of the 3SCC, which one can mutate to metal binding residues to create a minimal metal binding site, while solid phase synthesis allows our lab to easily incorporate a number of noncoded amino acids including d enantiomers of binding or secondary coordination sphere amino acids, penicillamine, or methylated versions of histidine. Our studies of Cd(II) binding to Cys3 environments have determined, largely through the use of 113Cd NMR and 111mCd PAC, that the coordination environment around a heavy metal can be controlled by incorporating noncoded amino acids in either the primary or secondary coordination spheres. We found mutating the metal binding amino acids to l-Pen can enforce trigonal Cd(II)S3 geometry exclusively compared to the mixed coordination determined for l-Cys coordination. The same result can be achieved with secondary sphere mutations as well by incorporating d-Leu above a Cys3. We hypothesize this latter effect is due to the increased steric packing above the metal binding site that occurs when the l-Leu oriented toward the N-terminus of the scaffold is mutated to d-Leu and oriented toward the C-terminus. Mutating the layer below Cys3 to d-Leu instead formed a mixed 4- and 5-coordinate Cd(II)S3(H2O) and Cd(II)S3(H2O)2 construct as steric bulk was decreased below the metal binding site. We have also applied noncoded amino acids to metalloenzyme systems by incorporating His residues that are methylated at the δ- or ε-nitrogen to enforce Cu(I) ligation to the opposite open nitrogen of His and found a 2 orders of magnitude increased catalytic efficiency for nitrite reductase activity with ε-nitrogen coordination compared to δ-nitrogen. These results exemplify the ability to tune coordination environment and catalytic efficiency within a de novo scaffold as well as the utility of noncoded amino acids to increase the chemist's toolbox. By furthering our understanding of metalloprotein design one could envision, through our use of amino acids not normally available to nature, that protein design laboratories will soon be capable of outperforming the native systems previously used as their benchmark of successful design. The ability to design proteins at this level would have far reaching and exciting benefits within various fields including medical and industrial applications.
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Affiliation(s)
- Karl J. Koebke
- Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109, United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109, United States
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15
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Ruckthong L, Stuckey JA, Pecoraro VL. How Outer Coordination Sphere Modifications Can Impact Metal Structures in Proteins: A Crystallographic Evaluation. Chemistry 2019; 25:6773-6787. [PMID: 30861211 PMCID: PMC6510599 DOI: 10.1002/chem.201806040] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Indexed: 11/06/2022]
Abstract
A challenging objective of de novo metalloprotein design is to control of the outer coordination spheres of an active site to fine tune metal properties. The well-defined three stranded coiled coils, TRI and CoilSer peptides, are used to address this question. Substitution of Cys for Leu yields a thiophilic site within the core. Metals such as HgII , PbII , and AsIII result in trigonal planar or trigonal pyramidal geometries; however, spectroscopic studies have shown that CdII forms three-, four- or five-coordinate CdII S3 (OH2 )x (in which x=0-2) when the outer coordination spheres are perturbed. Unfortunately, there has been little crystallographic examination of these proteins to explain the observations. Here, the high-resolution X-ray structures of apo- and mercurated proteins are compared to explain the modifications that lead to metal coordination number and geometry variation. It reveals that Ala substitution for Leu opens a cavity above the Cys site allowing for water excess, facilitating CdII S3 (OH2 ). Replacement of Cys by Pen restricts thiol rotation, causing a shift in the metal-binding plane, which displaces water, forming CdII S3 . Residue d-Leu, above the Cys site, reorients the side chain towards the Cys layer, diminishing the space for water accommodation yielding CdII S3 , whereas d-Leu below opens more space, allowing for equal CdII S3 (OH2 ) and CdII S3 (OH2 )2 . These studies provide insights into how to control desired metal geometries in metalloproteins by using coded and non-coded amino acids.
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Affiliation(s)
- Leela Ruckthong
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, USA
- Department of Chemistry, Faculty of Science, King Mongkut's University of Technology, Thonburi (KMUTT), Bang Mod, Thung Khru, Bangkok, 10140, Thailand
| | - Jeanne A Stuckey
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Vincent L Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, USA
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16
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Koebke KJ, Pecoraro VL. Development of de Novo Copper Nitrite Reductases: Where We Are and Where We Need To Go. ACS Catal 2018; 8:8046-8057. [PMID: 30294504 DOI: 10.1021/acscatal.8b02153] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The development of redox-active metalloprotein catalysts is a challenging objective of de novo protein design. Within this Perspective we detail our efforts to create a redox-active Cu nitrite reductase (NiR) by incorporating Cu into the hydrophobic interior of well-defined three-stranded coiled coils (3SCCs). The scaffold contains three histidine residues that provide a layer of three nitrogen donors that mimic the type 2 catalytic site of NiR. We have found that this strategy successfully produces an active and stable CuNiR model that functions for over 1000 turnovers. Spectroscopic evidence indicates that the Cu(I) site has a lower coordination number in comparison to the enzyme, whereas the Cu(II) geometry may more faithfully reproduce the NiR type 2 center. Mutations at the helical interface successfully produce a hydrogen bond between an interfacial Glu residue and the Culigating His residue, which allows for the tuning of the redox potential over a 100 mV range. We successfully created constructs with as much as a 120-fold improvement from the original design by modifying the steric bulk above or below the Cu binding site. These systems are now the most active water-soluble and stable artificial NiR catalysts yet produced. Several avenues for improving the catalytic efficiency of later designs are detailed within this Perspective, including adjustment of their resting oxidation state, the use of asymmetric scaffolds to allow for single amino acid mutation within the second coordination sphere, and the design of hydrogen-bonding networks to tune residue orientation and electronics. Through these studies the TRI-H system has given insight into the difficulties that arise in creating a de novo redox active enzyme. Work to improve upon this model will provide strategies by which redox-active de novo enzymes may be tuned and detail how native enzymes accomplish catalytic efficiencies through proton gated redox catalysis.
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Affiliation(s)
- Karl J. Koebke
- Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109, United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109, United States
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17
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Teare P, Smith CF, Adams SJ, Anbu S, Ciani B, Jeuken LJC, Peacock AFA. pH dependent binding in de novo hetero bimetallic coiled coils. Dalton Trans 2018; 47:10784-10790. [PMID: 30022210 DOI: 10.1039/c8dt01568f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein the first example of a bimetallic coiled coil featuring a lanthanide binding site is reported, opening opportunities to exploit the attractive NMR and photophysical properties of the lanthanides in multi metallo protein design. In our efforts to fully characterise the system we identified for the first time that lanthanide binding to such sites is pH dependent, with optimal binding at neutral pH, and that the double AsnAsp site is more versatile in this regard than the single Asp site. Our second site featured the structural HgCys3 site, the chemistry of which was essentially unaltered by the presence of the lanthanide site. In fact, both metal binding sites within the hetero bimetallic coiled coil displayed the same properties as their mononuclear single binding site controls, and operated independently of each other. Finally, pH can be used as an external trigger to control the binding of Hg(ii) and Tb(iii) to the two distinct sites within this coiled coil, and offers the opportunity to "activate" metal binding sites within complex multi metallo and multi-functional designs.
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Affiliation(s)
- Paul Teare
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Caitlin F Smith
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Samuel J Adams
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Sellamuthu Anbu
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Barbara Ciani
- Centre for Membrane Interactions and Dynamics, and Krebs Institute, Department of Chemistry, University of Sheffield, Sheffield, S3 7HF, UK
| | - Lars J C Jeuken
- School of Biomedical Sciences and the Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Anna F A Peacock
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.
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18
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Incorporation of second coordination sphere D-amino acids alters Cd(II) geometries in designed thiolate-rich proteins. J Biol Inorg Chem 2017; 23:123-135. [PMID: 29218636 DOI: 10.1007/s00775-017-1515-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/07/2017] [Indexed: 10/18/2022]
Abstract
We use a de Novo protein design strategy to demonstrate that the second coordination sphere of a metal site plays a key role in controlling coordination geometries of Cd(II)-tris-thiolate complexes. Specifically, we show that alteration of chirality within the core hydrophobic packing region of a three-stranded coiled coil (3SCC) can control the coordination number of Cd(II) by limiting steric encumbrance to the metal center. Within a specific class of 3SCCs [Ac-G-(LKALEEK) n -G-NH2], where n = 4 is TRI and n = 5 is GRAND, one L-Leu may be substituted by L-Cys to generate a planar tris-thiolate array capable of metal binding. In the native peptide containing only the L-configuration of leucine, the three-Cys ligand site leads to a mixture of 3- and 4-coordinate Cd(II). When the L-Leu above (toward the N-terminus) the tris-Cys site is substituted with D-Leu, solely a 3-coordinate structure [Cd(II)S3] was obtained. When D-Leu is located below (toward the C-terminus), a mixture of two coordination geometries, presumably Cd(II)S3O and Cd(II)S3O2, is observed, while substitution with D-Leu both above and below the tris-Cys plane yields a higher percentage of 4-coordinate Cd(II)S3O species. Thus, the use of D-amino acids around a metal's coordination sphere provides a powerful tool for controlling the properties of future designed metalloproteins.
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19
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Peng Y, Zhao Z, Liu T, Li X, Hu X, Wei X, Zhang X, Tan W. Smart Human-Serum-Albumin-As 2 O 3 Nanodrug with Self-Amplified Folate Receptor-Targeting Ability for Chronic Myeloid Leukemia Treatment. Angew Chem Int Ed Engl 2017; 56:10845-10849. [PMID: 28686804 PMCID: PMC5912668 DOI: 10.1002/anie.201701366] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/13/2017] [Indexed: 12/22/2022]
Abstract
Arsenic trioxide (ATO, As2 O3 ) is currently used to treat acute promyelocytic leukemia. However, expanding its use to include high-dose treatment of other cancers is severely hampered by serious side effects on healthy organs. To address these limitations, we loaded ATO onto folate (FA)-labeled human serum albumin (HSA) pretreated with glutathione (GSH) based on the low pH- and GSH-sensitive arsenic-sulfur bond, and we termed the resulting smart nanodrug as FA-HSA-ATO. FA-HSA-ATO could specifically recognize folate receptor-β-positive (FRβ+) chronic myeloid leukemia (CML) cells, resulting in more intracellular accumulation of ATO. Furthermore, the nanodrug could upregulate FRβ expression in CML cancer cells and xenograft tumor model, facilitating even more recruitment and uptake of FRβ-targeting drugs. In vitro and in vivo experiments indicate that the nanodrug significantly alleviates side effects and improves therapeutic efficacy of ATO on CML and xenograft tumor model.
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MESH Headings
- Animals
- Antineoplastic Agents/chemistry
- Antineoplastic Agents/pharmacology
- Arsenic Trioxide/chemistry
- Arsenic Trioxide/pharmacology
- Cell Proliferation/drug effects
- Dose-Response Relationship, Drug
- Drug Screening Assays, Antitumor
- Folate Receptor 2/antagonists & inhibitors
- Folate Receptor 2/metabolism
- Humans
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Mice
- Nanoparticles/chemistry
- Neoplasms, Experimental/drug therapy
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Serum Albumin, Human/chemistry
- Structure-Activity Relationship
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Affiliation(s)
- Yongbo Peng
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, 410082, China
| | - Zilong Zhao
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, 410082, China
| | - Teng Liu
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, 410082, China
- Department of Infectious Diseases, Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Xiong Li
- Department of Infectious Diseases, Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Xiaoxiao Hu
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, 410082, China
| | - Xiaoping Wei
- Center for Clinical Molecular Medicine, Ministry of Education Key Laboratory of Child Development and Dis-orders, Children's Hospital of Chongqing Medical University, Chongqing, 400014, China
| | - Xiaobing Zhang
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, 410082, China
| | - Weihong Tan
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, 410082, China
- Department of Chemistry, Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, UF Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, University of Florida, Gainesville, FL, 32611-7200, USA
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20
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Peng Y, Zhao Z, Liu T, Li X, Hu X, Wei X, Zhang X, Tan W. Smart Human-Serum-Albumin-As2O3Nanodrug with Self-Amplified Folate Receptor-Targeting Ability for Chronic Myeloid Leukemia Treatment. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701366] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Yongbo Peng
- Molecular Science and Biomedicine Laboratory; State Key Laboratory for Chemo/Bio-Sensing and Chemometrics; College of Chemistry and Chemical Engineering; College of Life Sciences; Aptamer Engineering Center of Hunan Province; Hunan University; Changsha 410082 China
| | - Zilong Zhao
- Molecular Science and Biomedicine Laboratory; State Key Laboratory for Chemo/Bio-Sensing and Chemometrics; College of Chemistry and Chemical Engineering; College of Life Sciences; Aptamer Engineering Center of Hunan Province; Hunan University; Changsha 410082 China
| | - Teng Liu
- Molecular Science and Biomedicine Laboratory; State Key Laboratory for Chemo/Bio-Sensing and Chemometrics; College of Chemistry and Chemical Engineering; College of Life Sciences; Aptamer Engineering Center of Hunan Province; Hunan University; Changsha 410082 China
- Department of Infectious Diseases; Xiangya Hospital; Central South University; Changsha 410008 China
| | - Xiong Li
- Department of Infectious Diseases; Xiangya Hospital; Central South University; Changsha 410008 China
| | - Xiaoxiao Hu
- Molecular Science and Biomedicine Laboratory; State Key Laboratory for Chemo/Bio-Sensing and Chemometrics; College of Chemistry and Chemical Engineering; College of Life Sciences; Aptamer Engineering Center of Hunan Province; Hunan University; Changsha 410082 China
| | - Xiaoping Wei
- Center for Clinical Molecular Medicine; Ministry of Education Key Laboratory of Child Development and Dis-orders; Children's Hospital of Chongqing Medical University; Chongqing 400014 China
| | - Xiaobing Zhang
- Molecular Science and Biomedicine Laboratory; State Key Laboratory for Chemo/Bio-Sensing and Chemometrics; College of Chemistry and Chemical Engineering; College of Life Sciences; Aptamer Engineering Center of Hunan Province; Hunan University; Changsha 410082 China
| | - Weihong Tan
- Molecular Science and Biomedicine Laboratory; State Key Laboratory for Chemo/Bio-Sensing and Chemometrics; College of Chemistry and Chemical Engineering; College of Life Sciences; Aptamer Engineering Center of Hunan Province; Hunan University; Changsha 410082 China
- Department of Chemistry; Department of Physiology and Functional Genomics; Center for Research at Bio/Nano Interface; UF Health Cancer Center, UF Genetics Institute and McKnight Brain Institute; University of Florida; Gainesville FL 32611-7200 USA
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21
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Ruckthong L, Peacock AFA, Pascoe CE, Hemmingsen L, Stuckey JA, Pecoraro VL. d-Cysteine Ligands Control Metal Geometries within De Novo Designed Three-Stranded Coiled Coils. Chemistry 2017; 23:8232-8243. [PMID: 28384393 DOI: 10.1002/chem.201700660] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Indexed: 12/31/2022]
Abstract
Although metal ion binding to naturally occurring l-amino acid proteins is well documented, understanding the impact of the opposite chirality (d-)amino acids on the structure and stereochemistry of metals is in its infancy. We examine the effect of a d-configuration cysteine within a designed l-amino acid three-stranded coiled coil in order to enforce a precise coordination number on a metal center. The d chirality does not alter the native fold, but the side-chain re-orientation modifies the sterics of the metal binding pocket. l-Cys side chains within the coiled-coil structure have previously been shown to rotate substantially from their preferred positions in the apo structure to create a binding site for a tetra-coordinate metal ion. However, here we show by X-ray crystallography that d-Cys side chains are preorganized within a suitable geometry to bind such a ligand. This is confirmed by comparison of the structure of ZnII Cl(CSL16D C)32- to the published structure of ZnII (H2 O)(GRAND-CSL12AL16L C)3- . Moreover, spectroscopic analysis indicates that the CdII geometry observed by using l-Cys ligands (a mixture of three- and four-coordinate CdII ) is altered to a single four-coordinate species when d-Cys is present. This work opens a new avenue for the control of the metal site environment in man-made proteins, by simply altering the binding ligand with its mirror-imaged d configuration. Thus, the use of non-coded amino acids in the coordination sphere of a metal promises to be a powerful tool for controlling the properties of future metalloproteins.
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Affiliation(s)
- Leela Ruckthong
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, USA
- Present address: Department Chemistry, Faculty of Science, King Mongkut's University of Technology Thonburi (KMUTT), Bang Mod, ThungKhru, Bangkok, 10140, Thailand
| | - Anna F A Peacock
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, USA
- Present address: School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Cherilyn E Pascoe
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Lars Hemmingsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, København Ø, Denmark
| | - Jeanne A Stuckey
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Vincent L Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109, USA
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22
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Cangelosi V, Ruckthong L, Pecoraro VL. Lead(II) Binding in Natural and Artificial Proteins. Met Ions Life Sci 2017; 17:/books/9783110434330/9783110434330-010/9783110434330-010.xml. [PMID: 28731303 PMCID: PMC5771651 DOI: 10.1515/9783110434330-010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This article describes recent attempts to understand the biological chemistry of lead using a synthetic biology approach. Lead binds to a variety of different biomolecules ranging from enzymes to regulatory and signaling proteins to bone matrix. We have focused on the interactions of this element in thiolate-rich sites that are found in metalloregulatory proteins such as Pbr, Znt, and CadC and in enzymes such as δ-aminolevulinic acid dehydratase (ALAD). In these proteins, Pb(II) is often found as a homoleptic and hemidirectic Pb(II)(SR)3- complex. Using first principles of biophysics, we have developed relatively short peptides that can associate into three-stranded coiled coils (3SCCs), in which a cysteine group is incorporated into the hydrophobic core to generate a (cysteine)3 binding site. We describe how lead may be sequestered into these sites, the characteristic spectral features may be observed for such systems and we provide crystallographic insight on metal binding. The Pb(II)(SR)3- that is revealed within these α-helical assemblies forms a trigonal pyramidal structure (having an endo orientation) with distinct conformations than are also found in natural proteins (having an exo conformation). This structural insight, combined with 207Pb NMR spectroscopy, suggests that while Pb(II) prefers hemidirected Pb(II)(SR)3- scaffolds regardless of the protein fold, the way this is achieved within α-helical systems is different than in β-sheet or loop regions of proteins. These interactions between metal coordination preference and protein structural preference undoubtedly are exploited in natural systems to allow for protein conformation changes that define function. Thus, using a design approach that separates the numerous factors that lead to stable natural proteins allows us to extract fundamental concepts on how metals behave in biological systems.
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23
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Garla R, Kaur N, Bansal MP, Garg ML, Mohanty BP. Quantum mechanical treatment of As 3+-thiol model compounds: implication for the core structure of As(III)-metallothionein. J Mol Model 2017; 23:78. [PMID: 28210877 DOI: 10.1007/s00894-017-3247-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 01/23/2017] [Indexed: 12/27/2022]
Abstract
Exposure to inorganic arsenic (As) is one of the major health concerns in several regions around the world. Binding of As(III) with thiols is central to the mechanisms related to its toxicity, detoxification, and therapeutic effects. Due to its high thiol content, metallothionein (MT) is presumed to play an important role in case of arsenic toxicity. Consequences of these As-thiol interactions are not yet clear due to various difficulties in the characterization of arsenic bound proteins by spectroscopic techniques. Computational modeling can be a reliable approach in predicting the molecular structures of such complexes. This paper presents the results of a systematic study on different As(III)-thiol model compounds conducted by both ab initio and DFT methods with different Gaussian type basis sets. Proficiency of these theoretical methods has been evaluated in terms of bond lengths, bond angles, free energy, partial atomic charges, computational cost, and comparison with the experimental data. It has been demonstrated that the DFT-B3LYP/6-311+G(3df) functional offers better accuracy in predicting the structure and the UV absorption spectra of As(III)-thiol complexes. The results of the present study also helps in defining the boundaries for the core of arsenic bound MT so that quantum mechanical/molecular mechanical (QM/MM) methods can be employed to predict the structural and functional aspects of the protein. Graphical Abstract Optimized structural parameters of As3+-thiol model compounds.
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Affiliation(s)
- Roobee Garla
- Department of Biophysics, Panjab University, Chandigarh, India, 160014
| | - Narinder Kaur
- Department of Biophysics, Panjab University, Chandigarh, India, 160014
| | | | - Mohan Lal Garg
- Department of Biophysics, Panjab University, Chandigarh, India, 160014
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24
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Plegaria JS, Pecoraro VL. De Novo Design of Metalloproteins and Metalloenzymes in a Three-Helix Bundle. Methods Mol Biol 2016; 1414:187-96. [PMID: 27094292 DOI: 10.1007/978-1-4939-3569-7_11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
For more than two decades, de novo protein design has proven to be an effective methodology for modeling native proteins. De novo design involves the construction of metal-binding sites within simple and/or unrelated α-helical peptide structures. The preparation of α3D, a single polypeptide that folds into a native-like three-helix bundle structure, has significantly expanded available de novo designed scaffolds. Devoid of a metal-binding site (MBS), we incorporated a 3Cys and 3His motif in α3D to construct a heavy metal and a transition metal center, respectively. These efforts produced excellent functional models for native metalloproteins/metalloregulatory proteins and metalloenzymes. Morever, these α3D derivatives serve as a foundation for constructing redox active sites with either the same (e.g., 4Cys) or mixed (e.g., 2HisCys) ligands, a feat that could be achieved in this preassembled framework. Here, we describe the process of constructing MBSs in α3D and our expression techniques.
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Affiliation(s)
- Jefferson S Plegaria
- Department of Chemistry, University of Michigan, 930 North University Ave., Ann Arbor, MI, 48910, USA
| | - Vincent L Pecoraro
- Department of Chemistry, University of Michigan, 930 North University Ave., Ann Arbor, MI, 48910, USA.
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25
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Stachura M, Chakraborty S, Gottberg A, Ruckthong L, Pecoraro VL, Hemmingsen L. Direct Observation of Nanosecond Water Exchange Dynamics at a Protein Metal Site. J Am Chem Soc 2016; 139:79-82. [PMID: 27973778 DOI: 10.1021/jacs.6b11525] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nanosecond ligand exchange dynamics at metal sites within proteins is essential in catalysis, metal ion transport, and regulatory metallobiochemistry. Herein we present direct observation of the exchange dynamics of water at a Cd2+ binding site within two de novo designed metalloprotein constructs using 111mCd perturbed angular correlation (PAC) of γ-rays and 113Cd NMR spectroscopy. The residence time of the Cd2+-bound water molecule is tens of nanoseconds at 20 °C in both proteins. This constitutes the first direct experimental observation of the residence time of Cd2+ coordinated water in any system, including the simple aqua ion. A Leu to Ala amino acid substitution ∼10 Å from the Cd2+ site affects both the equilibrium constant and the residence time of water, while, surprisingly, the metal site structure, as probed by PAC spectroscopy, remains essentially unaltered. This implies that remote mutations may affect metal site dynamics, even when structure is conserved.
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Affiliation(s)
- Monika Stachura
- Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 København Ø, Denmark
| | - Saumen Chakraborty
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109-1055, United States
| | | | - Leela Ruckthong
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109-1055, United States
| | - Vincent L Pecoraro
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109-1055, United States
| | - Lars Hemmingsen
- Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 København Ø, Denmark
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26
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Ruckthong L, Zastrow ML, Stuckey JA, Pecoraro VL. A Crystallographic Examination of Predisposition versus Preorganization in de Novo Designed Metalloproteins. J Am Chem Soc 2016; 138:11979-88. [PMID: 27532255 PMCID: PMC5242185 DOI: 10.1021/jacs.6b07165] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Preorganization and predisposition are important molecular recognition concepts exploited by nature to obtain site-specific and selective metal binding to proteins. While native structures containing an MS3 core are often unavailable in both apo- and holo-forms, one can use designed three-stranded coiled coils (3SCCs) containing tris-thiolate sites to evaluate these concepts. We show that the preferred metal geometry dictates the degree to which the cysteine rotamers change upon metal complexation. The Cys ligands in the apo-form are preorganized for binding trigonal pyramidal species (Pb(II)S3 and As(III)S3) in an endo conformation oriented toward the 3SCC C-termini, whereas the cysteines are predisposed for trigonal planar Hg(II)S3 and 4-coordinate Zn(II)S3O structures, requiring significant thiol rotation for metal binding. This study allows assessment of the importance of protein fold and side-chain reorientation for achieving metal selectivity in human retrotransposons and metalloregulatory proteins.
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Affiliation(s)
- Leela Ruckthong
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Melissa L. Zastrow
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jeanne A. Stuckey
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States
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27
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Ruckthong L, Stuckey JA, Pecoraro VL. Methods for Solving Highly Symmetric De Novo Designed Metalloproteins: Crystallographic Examination of a Novel Three-Stranded Coiled-Coil Structure Containing d-Amino Acids. Methods Enzymol 2016; 580:135-48. [PMID: 27586331 DOI: 10.1016/bs.mie.2016.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The core objective of de novo metalloprotein design is to define metal-protein relationships that control the structure and function of metal centers by using simplified proteins. An essential requirement to achieve this goal is to obtain high resolution structural data using either NMR or crystallographic studies in order to evaluate successful design. X-ray crystal structures have proven that a four heptad repeat scaffold contained in the three-stranded coiled coil (3SCC), called CoilSer (CS), provides an excellent motif for modeling a three Cys binding environment capable of chelating metals into geometries that resemble heavy metal sites in metalloregulatory systems. However, new generations of more complicated designs that feature, for example, a d-amino acid or multiple metal ligand sites in the helical sequence require a more stable construct. In doing so, an extra heptad was introduced into the original CS sequence, yielding a GRAND-CoilSer (GRAND-CS) to retain the 3SCC folding. An apo-(GRAND-CSL12DLL16C)3 crystal structure, designed for Cd(II)S3 complexation, proved to be a well-folded parallel 3SCC. Because this structure is novel, protocols for crystallization, structural determination, and refinements of the apo-(GRAND-CSL12DLL16C)3 are described. This report should be generally useful for future crystallographic studies of related coiled-coil designs.
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Affiliation(s)
- L Ruckthong
- Department of Chemistry, University of Michigan, Ann Arbor, MI, United States
| | - J A Stuckey
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, United States
| | - V L Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, MI, United States.
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28
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Wang PSP, Schepartz A. β-Peptide bundles: Design. Build. Analyze. Biosynthesize. Chem Commun (Camb) 2016; 52:7420-32. [PMID: 27146019 DOI: 10.1039/c6cc01546h] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Peptides containing β-amino acids are unique non-natural polymers known to assemble into protein-like tertiary and quaternary structures. When composed solely of β-amino acids, the structures formed, defined assemblies of 14-helices called β-peptide bundles, fold cooperatively in water solvent into unique and discrete quaternary assemblies that are highly thermostable, bind complex substrates and metal ion cofactors, and, in certain cases, catalyze chemical reactions. In this Perspective, we recount the design and elaboration of β-peptide bundles and provide an outlook on recent, unexpected discoveries that could influence research on β-peptides and β-peptide bundles (and β-amino acid-containing proteins) for decades to come.
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Affiliation(s)
- Pam S P Wang
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, CT 06511, USA.
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29
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Tebo AG, Hemmingsen L, Pecoraro VL. Variable primary coordination environments of Cd(II) binding to three helix bundles provide a pathway for rapid metal exchange. Metallomics 2015; 7:1555-61. [PMID: 26503746 DOI: 10.1039/c5mt00228a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Members of the ArsR/SmtB family of transcriptional repressors, such as CadC, regulate the intracellular levels of heavy metals like Cd(II), Hg(II), and Pb(II). These metal sensing proteins bind their target metals with high specificity and affinity, however, a lack of structural information about these proteins makes defining the coordination sphere of the target metal difficult. Lingering questions as to the identity of Cd(II) coordination in CadC are addressed via protein design techniques. Two designed peptides with tetrathiolate metal binding sites were prepared and characterized, revealing fast exchange between CdS3O and CdS4 coordination spheres. Correlation of (111m)Cd PAC spectroscopy and (113)Cd NMR spectroscopy suggests that Cd(II) coordinated to CadC is in fast exchange between CdS3O and CdS4 forms, which may provide a mechanism for rapid sensing of heavy metal contaminants by this regulatory protein.
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Affiliation(s)
- Alison G Tebo
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109, USA
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30
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Mocny CS, Pecoraro VL. De novo protein design as a methodology for synthetic bioinorganic chemistry. Acc Chem Res 2015; 48:2388-96. [PMID: 26237119 DOI: 10.1021/acs.accounts.5b00175] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The major advances in molecular and structural biology and automated peptide and DNA synthesis of the 1970s and 1980s generated fertile conditions in the 1990s for the exploration of designed proteins as a new approach for inorganic chemists to generate biomolecular mimics of metalloproteins. This Account follows the development of the TRI peptide family of three-stranded coiled coils (3SCC) and α3D family of three-helix bundles (3HB) as scaffolds for the preparation of metal binding sites within de novo designed constructs. The 3SCC were developed using the concept of a heptad repeat (abcdefg) putting hydrophobes in the a and d positions. The TRI peptides contain four heptads with capping glycines. Via substitution of leucine hydrophobes, metal ligands can be introduced into the a or d sites in order to bind metals. First, the ability to use cysteine-substituted 3SCC aggregates to impose higher or lower coordination numbers on Hg(II) and Cd(II) or matching the coordination preferences of As(III) and Pb(II) is discussed. Then, methods to develop dual site peptides capable of discriminating metals based on their type (e.g., Cd(II) vs Pb(II)), their preference for a vs d sites, and then their coordination number is described. Once these principles of metal site differentiation are described, we shift to building dual site peptides using both cysteine and histidine metal binding sites. This approach provides a construct with both a Hg(II) structural and a Zn(II) hydrolytic center, the latter of which is capable of hydrating CO2. With these Zn(II) proteins, we consider the relative importance of the location of the catalytic center along the primary sequence of the peptide and show that only minor perturbations in catalytic efficiencies are observed based on metal location. We then assess the feasibility of preparing enzymes competent to reduce nitrite with copper centers in a histidine-rich environment. As part of this discussion, we examine the influence of surface residues on catalyst reduction potentials and catalytic efficiencies. We end describing approaches to prepare asymmetric proteins that can incorporate acid-base catalysts or water channels. In this respect, we highlight modifications of a helix-turn-helix-turn-helix motif called α3D and show how this 3HB can be modified to bind heavy metals or to make Zn(II) centers, which are active hydrolytic catalysts. A comparison is made to the comparable parallel 3SCC.
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Affiliation(s)
- Catherine S. Mocny
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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31
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Flores M, Olson TL, Wang D, Edwardraja S, Shinde S, Williams JC, Ghirlanda G, Allen JP. Copper Environment in Artificial Metalloproteins Probed by Electron Paramagnetic Resonance Spectroscopy. J Phys Chem B 2015. [DOI: 10.1021/acs.jpcb.5b04172] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Marco Flores
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Tien L. Olson
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Dong Wang
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Selvakumar Edwardraja
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sandip Shinde
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - JoAnn C. Williams
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Giovanna Ghirlanda
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - James P. Allen
- Department
of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States
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32
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Amdursky N. Electron Transfer across Helical Peptides. Chempluschem 2015; 80:1075-1095. [DOI: 10.1002/cplu.201500121] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 05/06/2015] [Indexed: 02/05/2023]
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33
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Plegaria JS, Dzul SP, Zuiderweg ERP, Stemmler TL, Pecoraro VL. Apoprotein Structure and Metal Binding Characterization of a de Novo Designed Peptide, α3DIV, that Sequesters Toxic Heavy Metals. Biochemistry 2015; 54:2858-73. [PMID: 25790102 DOI: 10.1021/acs.biochem.5b00064] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
De novo protein design is a biologically relevant approach that provides a novel process in elucidating protein folding and modeling the metal centers of metalloproteins in a completely unrelated or simplified fold. An integral step in de novo protein design is the establishment of a well-folded scaffold with one conformation, which is a fundamental characteristic of many native proteins. Here, we report the NMR solution structure of apo α3DIV at pH 7.0, a de novo designed three-helix bundle peptide containing a triscysteine motif (Cys18, Cys28, and Cys67) that binds toxic heavy metals. The structure comprises 1067 NOE restraints derived from multinuclear multidimensional NOESY, as well as 138 dihedral angles (ψ, φ, and χ1). The backbone and heavy atoms of the 20 lowest energy structures have a root mean square deviation from the mean structure of 0.79 (0.16) Å and 1.31 (0.15) Å, respectively. When compared to the parent structure α3D, the substitution of Leu residues to Cys enhanced the α-helical content of α3DIV while maintaining the same overall topology and fold. In addition, solution studies on the metalated species illustrated metal-induced stability. An increase in the melting temperatures was observed for Hg(II), Pb(II), or Cd(II) bound α3DIV by 18-24 °C compared to its apo counterpart. Further, the extended X-ray absorption fine structure analysis on Hg(II)-α3DIV produced an average Hg(II)-S bond length at 2.36 Å, indicating a trigonal T-shaped coordination environment. Overall, the structure of apo α3DIV reveals an asymmetric distorted triscysteine metal binding site, which offers a model for native metalloregulatory proteins with thiol-rich ligands that function in regulating toxic heavy metals, such as ArsR, CadC, MerR, and PbrR.
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Affiliation(s)
| | - Stephen P Dzul
- #Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201, United States
| | | | - Timothy L Stemmler
- #Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201, United States
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34
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Density functional calculations of molecular structures of arsenic-binding β-domain of metallothioneins-2. COMPUT THEOR CHEM 2015. [DOI: 10.1016/j.comptc.2015.01.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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35
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Plegaria JS, Pecoraro VL. Sculpting Metal-binding Environments in De Novo Designed Three-helix Bundles. Isr J Chem 2015; 55:85-95. [PMID: 29353917 PMCID: PMC5771423 DOI: 10.1002/ijch.201400146] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
De novo protein design is a biologically relevant approach used to study the active centers of native metalloproteins. In this review, we will first discuss the design process in achieving α3D, a de novo designed three-helix bundle peptide with a well-defined fold. We will then cover our recent work in functionalizing the α3D framework by incorporating a tris(cysteine) and tris(histidine) motif. Our first design contains the thiol-rich sites found in metalloregulatory proteins that control the levels of toxic metal ions (Hg, Cd, and Pb). The latter design recapitulates the catalytic site and activity of a natural metalloenzyme carbonic anhydrase. The review will conclude with future design goals aimed at introducing an asymmetric metal-binding site in the α3D framework.
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Affiliation(s)
- Jefferson S Plegaria
- 930 North University Ave, Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109 (USA)
| | - Vincent L Pecoraro
- 930 North University Ave, Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109 (USA)
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36
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Yu F, Cangelosi VM, Zastrow ML, Tegoni M, Plegaria JS, Tebo AG, Mocny CS, Ruckthong L, Qayyum H, Pecoraro VL. Protein design: toward functional metalloenzymes. Chem Rev 2014; 114:3495-578. [PMID: 24661096 PMCID: PMC4300145 DOI: 10.1021/cr400458x] [Citation(s) in RCA: 340] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Fangting Yu
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | | | | | | | - Alison G. Tebo
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | - Leela Ruckthong
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hira Qayyum
- University of Michigan, Ann Arbor, Michigan 48109, United States
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37
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Zastrow M, Pecoraro VL. Designing hydrolytic zinc metalloenzymes. Biochemistry 2014; 53:957-78. [PMID: 24506795 PMCID: PMC3985962 DOI: 10.1021/bi4016617] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 01/23/2014] [Indexed: 12/15/2022]
Abstract
Zinc is an essential element required for the function of more than 300 enzymes spanning all classes. Despite years of dedicated study, questions regarding the connections between primary and secondary metal ligands and protein structure and function remain unanswered, despite numerous mechanistic, structural, biochemical, and synthetic model studies. Protein design is a powerful strategy for reproducing native metal sites that may be applied to answering some of these questions and subsequently generating novel zinc enzymes. From examination of the earliest design studies introducing simple Zn(II)-binding sites into de novo and natural protein scaffolds to current studies involving the preparation of efficient hydrolytic zinc sites, it is increasingly likely that protein design will achieve reaction rates previously thought possible only for native enzymes. This Current Topic will review the design and redesign of Zn(II)-binding sites in de novo-designed proteins and native protein scaffolds toward the preparation of catalytic hydrolytic sites. After discussing the preparation of Zn(II)-binding sites in various scaffolds, we will describe relevant examples for reengineering existing zinc sites to generate new or altered catalytic activities. Then, we will describe our work on the preparation of a de novo-designed hydrolytic zinc site in detail and present comparisons to related designed zinc sites. Collectively, these studies demonstrate the significant progress being made toward building zinc metalloenzymes from the bottom up.
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Affiliation(s)
| | - Vincent L. Pecoraro
- Department of Chemistry, University
of Michigan, Ann Arbor, Michigan 48109, United
States
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38
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Zhou L, Bosscher M, Zhang C, Özçubukçu S, Zhang L, Zhang W, Li CJ, Liu J, Jensen MP, Lai L, He C. A protein engineered to bind uranyl selectively and with femtomolar affinity. Nat Chem 2014; 6:236-41. [DOI: 10.1038/nchem.1856] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 12/17/2013] [Indexed: 12/24/2022]
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39
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Gamble AJ, Peacock AFA. De novo design of peptide scaffolds as novel preorganized ligands for metal-ion coordination. Methods Mol Biol 2014; 1216:211-31. [PMID: 25213418 DOI: 10.1007/978-1-4939-1486-9_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This chapter describes how de novo designed peptides can be used as novel preorganized ligands for metal ion coordination. The focus is on the design of peptides which are programmed to spontaneously self-assemble into α-helical coiled coils in aqueous solution, and how metal ion binding sites can be engineered onto and into these structures. In addition to describing the various design principles, some key examples are covered illustrating the success of this approach, including a more detailed example in the case study.
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Affiliation(s)
- Aimee J Gamble
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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40
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Mitra J, Pal K, Sarkar S. Second order non-linear optical activity of arsenic and antimony dithiolene complexes. Dalton Trans 2013; 42:13905-11. [PMID: 23925121 DOI: 10.1039/c3dt51585k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Synthesis and characterization of dithiolene complexes of arsenic and antimony in trivalent state have been reported. A four coordinated structural motif results in a ladder like arrangement in the arsenic complex due to the inter-anionic As-S interaction which is replaced by Sb-π interaction with the counter cation in the solid state structure of the similar antimony complex. Electronic structure calculations on ground state geometries and the time-dependent density functional theoretical calculations were performed in order to characterize the absorption spectra incorporating solvent effects. Notably, both the complexes display intense second order optical non-linearity as has been determined using hyper-Rayleigh scattering technique in dichloromethane solution and the results are corroborated by DFT calculations.
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Affiliation(s)
- Joyee Mitra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, UP, India.
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41
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Affiliation(s)
- Shengwen Shen
- Department
of Laboratory Medicine
and Pathology, 10-102 Clinical Sciences Building, University
of Alberta, Edmonton, Alberta, Canada, T6G 2G3
| | - Xing-Fang Li
- Department
of Laboratory Medicine
and Pathology, 10-102 Clinical Sciences Building, University
of Alberta, Edmonton, Alberta, Canada, T6G 2G3
| | - William R. Cullen
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver,
British Columbia, Canada, V6T 1Z1
| | - Michael Weinfeld
- Department of Oncology, Cross
Cancer Institute, University of Alberta, 11560 University Avenue, Edmonton, Alberta, Canada, T6G 1Z2
| | - X. Chris Le
- Department
of Laboratory Medicine
and Pathology, 10-102 Clinical Sciences Building, University
of Alberta, Edmonton, Alberta, Canada, T6G 2G3
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42
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Zastrow ML, Pecoraro VL. Designing functional metalloproteins: from structural to catalytic metal sites. Coord Chem Rev 2013; 257:2565-2588. [PMID: 23997273 PMCID: PMC3756834 DOI: 10.1016/j.ccr.2013.02.007] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Metalloenzymes efficiently catalyze some of the most important and difficult reactions in nature. For many years, coordination chemists have effectively used small molecule models to understand these systems. More recently, protein design has been shown to be an effective approach for mimicking metal coordination environments. Since the first designed proteins were reported, much success has been seen for incorporating metal sites into proteins and attaining the desired coordination environment but until recently, this has been with a lack of significant catalytic activity. Now there are examples of designed metalloproteins that, although not yet reaching the activity of native enzymes, are considerably closer. In this review, we highlight work leading up to the design of a small metalloprotein containing two metal sites, one for structural stability (HgS3) and the other a separate catalytic zinc site to mimic carbonic anhydrase activity (ZnN3O). The first section will describe previous studies that allowed for a high affinity thiolate site that binds heavy metals in a way that stabilizes three-stranded coiled coils. The second section will examine ways of preparing histidine rich environments that lead to metal based hydrolytic catalysts. We will also discuss other recent examples of the design of structural metal sites and functional metalloenzymes. Our work demonstrates that attaining the proper first coordination geometry of a metal site can lead to a significant fraction of catalytic activity, apparently independent of the type of secondary structure of the surrounding protein environment. We are now in a position to begin to meet the challenge of building a metalloenzyme systematically from the bottom-up by engineering and analyzing interactions directly around the metal site and beyond.
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Affiliation(s)
- Melissa L. Zastrow
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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43
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Łuczkowski M, Zeider BA, Hinz AVH, Stachura M, Chakraborty S, Hemmingsen L, Huffman DL, Pecoraro VL. Probing the coordination environment of the human copper chaperone HAH1: characterization of Hg(II)-bridged homodimeric species in solution. Chemistry 2013; 19:9042-9. [PMID: 23677531 DOI: 10.1002/chem.201204184] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 04/16/2013] [Indexed: 01/23/2023]
Abstract
Although metal ion homeostasis in cells is often mediated through metallochaperones, there are opportunities for toxic metals to be sequestered through the existing transport apparatus. Proper trafficking of Cu(I) in human cells is partially achieved through complexation by HAH1, the human metallochaperone responsible for copper delivery to the Wilson and Menkes ATPase located in the trans-Golgi apparatus. In addition to binding copper, HAH1 strongly complexes Hg(II), with the X-ray structure of this complex previously described. It is important to clarify the solution behavior of these systems and, therefore, the binding of Hg(II) to HAH1 was probed over the pH range 7.5 to 9.4 using (199)Hg NMR, (199m)Hg PAC and UV-visible spectroscopies. The metal-dependent protein association over this pH range was examined using analytical gel-filtration. It can be concluded that at pH 7.5, Hg(II) is bound to a monomeric HAH1 as a two coordinate, linear complex (HgS2), like the Hg(II)-Atx1 X-ray structure (PDB ID: 1CC8). At pH 9.4, Hg(II) promotes HAH1 association, leading to formation of HgS3 and HgS4 complexes, which are in exchange on the μs-ns time scale. Thus, structures that may represent central intermediates in the process of metal ion transfer, as well as their exchange kinetics have been characterized.
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Affiliation(s)
- Marek Łuczkowski
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
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Zastrow ML, Pecoraro VL. Influence of active site location on catalytic activity in de novo-designed zinc metalloenzymes. J Am Chem Soc 2013; 135:5895-903. [PMID: 23516959 DOI: 10.1021/ja401537t] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
While metalloprotein design has now yielded a number of successful metal-bound and even catalytically active constructs, the question of where to put a metal site along a linear, repetitive sequence has not been thoroughly addressed. Often several possibilities in a given sequence may exist that would appear equivalent but may in fact differ for metal affinity, substrate access, or protein dynamics. We present a systematic variation of active site location for a hydrolytically active ZnHis3O site contained within a de novo-designed three-stranded coiled coil. We find that the maximal rate, substrate access, and metal-binding affinity are dependent on the selected position, while catalytic efficiency for p-nitrophenyl acetate hydrolysis can be retained regardless of the location of the active site. This achievement demonstrates how efficient, tailor-made enzymes which control rate, pKa, substrate and solvent access (and selectivity), and metal-binding affinity may be realized. These findings may be applied to the more advanced de novo design of constructs containing secondary interactions, such as hydrogen-bonding channels. We are now confident that changes to location for accommodating such channels can be achieved without location-dependent loss of catalytic efficiency. These findings bring us closer to our ultimate goal of incorporating the secondary interactions we believe will be necessary in order to improve both active site properties and the catalytic efficiency to be competitive with the native enzyme, carbonic anhydrase.
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Affiliation(s)
- Melissa L Zastrow
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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Zaytsev DV, Morozov VA, Fan J, Zhu X, Mukherjee M, Ni S, Kennedy MA, Ogawa MY. Metal-binding properties and structural characterization of a self-assembled coiled coil: Formation of a polynuclear Cd–thiolate cluster. J Inorg Biochem 2013; 119:1-9. [DOI: 10.1016/j.jinorgbio.2012.10.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/22/2012] [Accepted: 10/23/2012] [Indexed: 01/10/2023]
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Abstract
This chapter describes an approach using designed proteins to understand the structure, spectroscopy, and dynamics of proteins that bind Cd(II). We will show that three-stranded coiled coils (3SCCs) based on the parent peptides TRI (Ac-G(LKALEEK)(4)G-NH(2)) or GRAND (Ac-G(LKALEEK)(5)G-NH(2)) have been essential for understanding how Cd(II) binds to thiolate-rich environments in proteins. Examples are given correlating physical properties such as the binding constants or deprotonation constants relating to structure. We present a scale that relates (113)Cd NMR chemical shifts to structures extracted from (111m)Cd PAC experiments. In addition, we describe motional processes that help transport from the helical interface of proteins into the hydrophobic interior of helical bundles. These studies help clarify the chemistry of Cd(II) in relation to metal-regulated gene expression and detoxification.
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Cha SS, An YJ, Jeong CS, Kim MK, Lee SG, Lee KH, Oh BH. Experimental phasing using zinc anomalous scattering. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:1253-8. [PMID: 22948927 PMCID: PMC3489106 DOI: 10.1107/s0907444912024420] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/29/2012] [Indexed: 02/06/2023]
Abstract
Zinc is a suitable metal for anomalous dispersion phasing methods in protein crystallography. Structure determination using zinc anomalous scattering has been almost exclusively limited to proteins with intrinsically bound zinc(s). Here, it is reported that multiple zinc ions can easily be charged onto the surface of proteins with no intrinsic zinc-binding site by using zinc-containing solutions. Zn derivatization of protein surfaces appears to be a largely unnoticed but promising method of protein structure determination.
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Affiliation(s)
- Sun-Shin Cha
- Marine Biotechnology Research Center, Korea Institute of Ocean Science and Technology, Ansan 426-744, Republic of Korea.
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Murase S, Ishino S, Ishino Y, Tanaka T. Control of enzyme reaction by a designed metal-ion-dependent α-helical coiled-coil protein. J Biol Inorg Chem 2012; 17:791-9. [PMID: 22466407 DOI: 10.1007/s00775-012-0896-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 03/20/2012] [Indexed: 01/01/2023]
Abstract
Regulation of protein function by external stimuli is a fascinating target for de novo design. We have constructed a peptide that assembles into a homotrimer in the presence of metal ions, such as Ni(2+), Cu(2+), and Zn(2+). We fused the peptide construct to the DNA-binding domain (DBD) of the heat shock factor from Saccharomyces cerevisiae, which binds tandem repeats of the heat shock element (HSE). However, the fusion protein bound to the natural three tandem HSEs even in the absence of metal ions, although mainly as the dimerized protein. Using "skipped" HSEs containing six additional nucleotides inserted between two adjacent HSEs, to prevent interactions between the DBDs, we found the fusion protein bound to the new DNA target in a metal-ion-dependent manner, as monitored by a HindIII protection assay. The fusion protein containing two metal binding sites in the metal-ion-controlled domain inhibited RNA transcription by T7 RNA polymerase in the presence of metal ions, in a template containing skipped HSEs downstream of the T7 promoter. The designed protein therefore regulates the functions of the enzyme in a metal-ion-dependent manner.
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Affiliation(s)
- Shigeo Murase
- Department of Material Sciences, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-chou, Nagoya, 466-8555, Japan
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Chakraborty S, Iranzo O, Zuiderweg ERP, Pecoraro VL. Experimental and theoretical evaluation of multisite cadmium(II) exchange in designed three-stranded coiled-coil peptides. J Am Chem Soc 2012; 134:6191-203. [PMID: 22394049 DOI: 10.1021/ja210510g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An important factor that defines the toxicity of elements such as cadmium(II), mercury(II), and lead(II) with biological macromolecules is metal ion exchange dynamics. Intriguingly, little is known about the fundamental rates and mechanisms of metal ion exchange into proteins, especially helical bundles. Herein, we investigate the exchange kinetics of Cd(II) using de novo designed three-stranded coiled-coil peptides that contain metal complexing cysteine thiolates as a model for the incorporation of this ion into trimeric, parallel coiled coils. Peptides were designed containing both a single Cd(II) binding site, GrandL12AL16C [Grand = AcG-(LKALEEK)(5)-GNH(2)], GrandL26AL30C, and GrandL26AE28QL30C, as well as GrandL12AL16CL26AL30C with two Cd(II) binding sites. The binding of Cd(II) to any of these sites is of high affinity (K(A) > 3 × 10(7) M(-1)). Using (113)Cd NMR spectroscopy, Cd(II) binding to these designed peptides was monitored. While the Cd(II) binding is in extreme slow exchange regime without showing any chemical shift changes, incremental line broadening for the bound (113)Cd(II) signal is observed when excess (113)Cd(II) is titrated into the peptides. Most dramatically, for one site, L26AL30C, all (113)Cd(II) NMR signals disappear once a 1.7:1 ratio of Cd(II)/(peptide)(3) is reached. The observed processes are not compatible with a simple "free-bound" two-site exchange kinetics at any time regime. The experimental results can, however, be simulated in detail with a multisite binding model, which features additional Cd(II) binding site(s) which, once occupied, perturb the primary binding site. This model is expanded into differential equations for five-site NMR chemical exchange. The numerical integration of these equations exhibits progressive loss of the primary site NMR signal without a chemical shift change and with limited line broadening, in good agreement with the observed experimental data. The mathematical model is interpreted in molecular terms as representing binding of excess Cd(II) to surface Glu residues located at the helical interfaces. In the absence of Cd(II), the Glu residues stabilize the three-helical structure though salt bridge interactions with surface Lys residues. We hypothesize that Cd(II) interferes with these surface ion pairs, destabilizing the helical structure, and perturbing the primary Cd(II) binding site. This hypothesis is supported by the observation that the Cd(II)-excess line broadening is attenuated in GrandL26AE28QL30C, where a surface Glu(28), close to the metal binding site, was changed to Gln. The external binding site may function as an entry pathway for Cd(II) to find its internal binding site following a molecular rearrangement which may serve as a basis for our understanding of metal complexation, transport, and exchange in complex native systems containing α-helical bundles.
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Affiliation(s)
- Saumen Chakraborty
- Department of Chemistry, University of Michigan, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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50
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Zampella G, Neupane KP, De Gioia L, Pecoraro VL. The importance of stereochemically active lone pairs for influencing Pb(II) and As(III) protein binding. Chemistry 2012; 18:2040-50. [PMID: 22231489 PMCID: PMC3357087 DOI: 10.1002/chem.201102786] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Indexed: 10/14/2022]
Abstract
The toxicity of heavy metals, which is associated with the high affinity of the metals for thiolate rich proteins, constitutes a problem worldwide. However, despite this tremendous toxicity concern, the binding mode of As(III) and Pb(II) to proteins is poorly understood. To clarify the requirements for toxic metal binding to metalloregulatory sensor proteins such as As(III) in ArsR/ArsD and Pb(II) in PbrR or replacing Zn(II) in δ-aminolevulinc acid dehydratase (ALAD), we have employed computational and experimental methods examining the binding of these heavy metals to designed peptide models. The computational results show that the mode of coordination of As(III) and Pb(II) is greatly influenced by the steric bulk within the second coordination environment of the metal. The proposed basis of this selectivity is the large size of the ion and, most important, the influence of the stereochemically active lone pair in hemidirected complexes of the metal ion as being crucial. The experimental data show that switching a bulky leucine layer above the metal binding site by a smaller alanine residue enhances the Pb(II) binding affinity by a factor of five, thus supporting experimentally the hypothesis of lone pair steric hindrance. These complementary approaches demonstrate the potential importance of a stereochemically active lone pair as a metal recognition mode in proteins and, specifically, how the second coordination sphere environment affects the affinity and selectivity of protein targets by certain toxic ions.
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Affiliation(s)
- Giuseppe Zampella
- Department of Biotechnology and Biosciences, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan (Italy), Tel: + 39 02 64483416, Fax: +39 02 64483478,
| | - Kosh P. Neupane
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109 (USA), Tel.: +1 734 763 1519, Fax: +1 734 936 7628,
| | - Luca De Gioia
- Department of Biotechnology and Biosciences, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan (Italy), Tel: + 39 02 64483416, Fax: +39 02 64483478,
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109 (USA), Tel.: +1 734 763 1519, Fax: +1 734 936 7628,
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