1
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Verma S, Nair NN. A Comprehensive Study of Factors Affecting the Prediction of the p Ka Shift of Asp 26 in Thioredoxin Protein. J Phys Chem B 2024; 128:7304-7312. [PMID: 39023356 DOI: 10.1021/acs.jpcb.4c01516] [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: 07/20/2024]
Abstract
The stable protonation state of ionizable amino acids in a protein can be predicted by computing the pKa shift of that residue within the protein environment. Thermodynamic Integration (TI) is an ideal molecular dynamics-based approach for predicting the pKa shift of ionizable protein residues. Here, we probe TI-based simulation protocols for their ability to accurately predict the pKa shift of Asp26 in thioredoxin. While implicit solvent models can predict the pKa shift accurately, explicit solvent models result in substantial errors. To understand the underlying reason for this surprising discrepancy, we investigate the role of various factors such as solvent models, conformational sampling, background charges, and polarization.
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Affiliation(s)
- Shivani Verma
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur - 208016, India
| | - Nisanth N Nair
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur - 208016, India
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2
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Ononugbo CM, Shimura Y, Yamano-Adachi N, Omasa T, Koga Y. Rational design approach to improve the solubility of the β-sandwich domain 1 of a thermophilic protein. J Biosci Bioeng 2024:S1389-1723(24)00188-9. [PMID: 39074993 DOI: 10.1016/j.jbiosc.2024.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 05/28/2024] [Accepted: 06/20/2024] [Indexed: 07/31/2024]
Abstract
The β-sandwich domain 1 (SD1) of islandisin is a stable thermophilic protein with surface loops that can be redesigned for specific target binding, architecturally comparable to the variable domain of immunoglobulin (IgG). SD1's propensity to aggregate due to incorrect folding and subsequent accumulation in Escherichia coli inclusion bodies limits its use in biotechnological applications. We rationally designed SD1 for improved variants that were expressed in soluble forms in E. coli while maintaining the intrinsic thermal stability of the protein (melting temperature (Tm) = 73). We used FoldX's ΔΔG predictions to find beneficial mutations and aggregation-prone regions (APRs) using Tango. The S26K substitution within protein core residues did not affect protein stability. Among the soluble mutants studied, the S26K/Q91P combination significantly improved the expression and solubility of SD1. We also examined the effects of the surface residue, pH, and concentration on the solubility of SD1. We showed that the surface polarity of proteins had little or no effect on solubility, whereas surface charges played a substantial role. The storage stability of several SD1 variants was impaired at pH values near their isoelectric point, and pH levels resulting in highly charged groups. We observed that mutations that create an uneven distribution of charged groups on the SD1 surface could enhance protein solubility by eliminating favorable protein-protein surface charge interactions. Our findings suggest that SD1 is mutationally tolerant to new functionalities, thus providing a novel perspective for the application of rational design to improve the solubility of targeted proteins.
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Affiliation(s)
- Chukwuebuka M Ononugbo
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yusaku Shimura
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Noriko Yamano-Adachi
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takeshi Omasa
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuichi Koga
- Department of Applied Chemistry, Faculty of Engineering, Okayama University of Science, 1-1 Ridaicho, Kitaku, Okayama 700-0005, Japan.
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3
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Olgenblum GI, Hutcheson BO, Pielak GJ, Harries D. Protecting Proteins from Desiccation Stress Using Molecular Glasses and Gels. Chem Rev 2024; 124:5668-5694. [PMID: 38635951 PMCID: PMC11082905 DOI: 10.1021/acs.chemrev.3c00752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 02/18/2024] [Accepted: 02/22/2024] [Indexed: 04/20/2024]
Abstract
Faced with desiccation stress, many organisms deploy strategies to maintain the integrity of their cellular components. Amorphous glassy media composed of small molecular solutes or protein gels present general strategies for protecting against drying. We review these strategies and the proposed molecular mechanisms to explain protein protection in a vitreous matrix under conditions of low hydration. We also describe efforts to exploit similar strategies in technological applications for protecting proteins in dry or highly desiccated states. Finally, we outline open questions and possibilities for future explorations.
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Affiliation(s)
- Gil I. Olgenblum
- Institute
of Chemistry, Fritz Haber Research Center, and The Harvey M. Krueger
Family Center for Nanoscience & Nanotechnology, The Hebrew University, Jerusalem 9190401, Israel
| | - Brent O. Hutcheson
- Department
of Chemistry, University of North Carolina
at Chapel Hill (UNC-CH), Chapel
Hill, North Carolina 27599, United States
| | - Gary J. Pielak
- Department
of Chemistry, University of North Carolina
at Chapel Hill (UNC-CH), Chapel
Hill, North Carolina 27599, United States
- Department
of Chemistry, Department of Biochemistry & Biophysics, Integrated
Program for Biological & Genome Sciences, Lineberger Comprehensive
Cancer Center, University of North Carolina
at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Daniel Harries
- Institute
of Chemistry, Fritz Haber Research Center, and The Harvey M. Krueger
Family Center for Nanoscience & Nanotechnology, The Hebrew University, Jerusalem 9190401, Israel
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4
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Zhu F, Yan Z, Dai J, Li G, Xu Q, Ma Y, Ma J, Chen N, Zhang X, Zang Y. Improvement in organic solvent resistance of keratinase BLk by directed evolution. J Biotechnol 2024; 382:37-43. [PMID: 38244699 DOI: 10.1016/j.jbiotec.2024.01.007] [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: 10/27/2023] [Revised: 01/11/2024] [Accepted: 01/15/2024] [Indexed: 01/22/2024]
Abstract
Keratinase, a vital enzyme in hair degradation, requires enhanced stability for industrial applications in the harsh reaction environment used for keratin hydrolysis. Previous studies have focused on improving keratinase thermostability. In this study, directed evolution was applied to enhance the organic solvent stability of the keratinase BLk from Bacillus licheniformis. Three mutants were identified, exhibiting significant enhanced stability in various solvents, although no similar improvements were observed in terms of thermostability. The identified mutations were located on the enzyme surface. The half-lives of the D41A, A24E, and A24Q mutants increased by 47-, 63-, and 61-fold, respectively, in the presence of 50% (v/v) acetonitrile compared to that of the wild type (WT). Similarly, in the presence of 50% (v/v) acetone, the half-lives of these mutants increased by 22-, 27-, and 27-fold compared to that of the WT enzyme. Notably, the proteolytic activity of all the selected mutants was similar to that of the WT enzyme. Furthermore, molecular dynamics simulation was used to assess the possible reasons for enhanced solvent stability. These results suggest that heightened intramolecular interactions, such as hydrogen bonding and hydrophobic interactions, contribute to improved solvent tolerance. The mutants obtained in this study hold significant potential for industrial applications.
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Affiliation(s)
- Fucheng Zhu
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China.
| | - Zixu Yan
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China
| | - Jingli Dai
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China
| | - Guosi Li
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China
| | - Qilin Xu
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China
| | - Yunfeng Ma
- Anhui Anlito Biological Technology Co., LTD, Anhui Huoshan Economic and Technological Development Zone P.R.C, Lu'an city 237200, China
| | - Jingbo Ma
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China
| | - Naidong Chen
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China
| | - Xinhong Zhang
- School of Biology, Food and Environment, Hefei University, Hefei 230630, China.
| | - Yongjun Zang
- College of Biological and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, Anhui Province Key Laboratory for Quality Evaluation and Improvement of Traditional Chinese Medicine, West Anhui University, Lu'an city 237012, China.
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5
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Lincon A, Mohapatra P, Das S, DasGupta S. Probing silver nanoparticle mediated mitigation of UV-photolysis in proteins by electrical impedance analysis. Int J Biol Macromol 2024; 256:128271. [PMID: 38000604 DOI: 10.1016/j.ijbiomac.2023.128271] [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: 08/30/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 11/26/2023]
Abstract
The dynamic equilibrium between an array of molecular forces precisely organizes the native structure of the protein. The charge on the protein, an interconnected network continuum, is crucial in determining its secondary and tertiary structure. The photolysis of the protein by ultraviolet (UV) light occurs by generating reactive oxygen intermediates from the interaction of matter and light. Herein, we have investigated the photolysis of the protein and its prevention by the pre-treatment with silver nanoparticle (AgNP) using non-faradaic electrical impedance spectroscopy (Nf-EIS). Five microliters of protein solution are used to measure its impedimetric parameters via Nf-EIS. The photoionization process sparks off an altered surface charge continuum of the protein molecules in tandem with the genesis of solvated electrons and protons, spurring an upward shift in conductivity. The AgNP pre-treatment has reduced the damaging effects of the UV radiation, which is reflected as lesser conductivity in contrast to the photolyzed protein solution. Raman Spectroscopy and circular dichroism tests affirm the trend of Nf-EIS results. These results show that Nf-EIS can evaluate protein structure analysis utilized in quality assurance and toxicity analysis for biologics.
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Affiliation(s)
- Abhijit Lincon
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, India
| | - Pratyusa Mohapatra
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, India
| | - Soumen Das
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, India
| | - Sunando DasGupta
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, India.
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6
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Park E, Izadi S. Molecular surface descriptors to predict antibody developability: sensitivity to parameters, structure models, and conformational sampling. MAbs 2024; 16:2362788. [PMID: 38853585 PMCID: PMC11168226 DOI: 10.1080/19420862.2024.2362788] [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: 11/28/2023] [Accepted: 05/29/2024] [Indexed: 06/11/2024] Open
Abstract
In silico assessment of antibody developability during early lead candidate selection and optimization is of paramount importance, offering a rapid and material-free screening approach. However, the predictive power and reproducibility of such methods depend heavily on the selection of molecular descriptors, model parameters, accuracy of predicted structure models, and conformational sampling techniques. Here, we present a set of molecular surface descriptors specifically designed for predicting antibody developability. We assess the performance of these descriptors by benchmarking their correlations with an extensive array of experimentally determined biophysical properties, including viscosity, aggregation, hydrophobic interaction chromatography, human pharmacokinetic clearance, heparin retention time, and polyspecificity. Further, we investigate the sensitivity of these surface descriptors to methodological nuances, such as the choice of interior dielectric constant, hydrophobicity scales, structure prediction methods, and the impact of conformational sampling. Notably, we observe systematic shifts in the distribution of surface descriptors depending on the structure prediction method used, driving weak correlations of surface descriptors across structure models. Averaging the descriptor values over conformational distributions from molecular dynamics mitigates the systematic shifts and improves the consistency across different structure prediction methods, albeit with inconsistent improvements in correlations with biophysical data. Based on our benchmarking analysis, we propose six in silico developability risk flags and assess their effectiveness in predicting potential developability issues for a set of case study molecules.
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Affiliation(s)
- Eliott Park
- Pharmaceutical Development, Genentech Inc, South San Francisco, CA, USA
| | - Saeed Izadi
- Pharmaceutical Development, Genentech Inc, South San Francisco, CA, USA
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7
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Wilson C, Karttunen M, de Groot BL, Gapsys V. Accurately Predicting Protein p Ka Values Using Nonequilibrium Alchemy. J Chem Theory Comput 2023; 19:7833-7845. [PMID: 37820376 PMCID: PMC10653114 DOI: 10.1021/acs.jctc.3c00721] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Indexed: 10/13/2023]
Abstract
The stability, solubility, and function of a protein depend on both its net charge and the protonation states of its individual residues. pKa is a measure of the tendency for a given residue to (de)protonate at a specific pH. Although pKa values can be resolved experimentally, theory and computation provide a compelling alternative. To this end, we assess the applicability of a nonequilibrium (NEQ) alchemical free energy method to the problem of pKa prediction. On a data set of 144 residues that span 13 proteins, we report an average unsigned error of 0.77 ± 0.09, 0.69 ± 0.09, and 0.52 ± 0.04 pK for aspartate, glutamate, and lysine, respectively. This is comparable to current state-of-the-art predictors and the accuracy recently reached using free energy perturbation methods (e.g., FEP+). Moreover, we demonstrate that our open-source, pmx-based approach can accurately resolve the pKa values of coupled residues and observe a substantial performance disparity associated with the lysine partial charges in Amber14SB/Amber99SB*-ILDN, for which an underused fix already exists.
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Affiliation(s)
- Carter
J. Wilson
- Department
of Mathematics, The University of Western
Ontario, N6A 5B7 London, Canada
- Centre
for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, N6A 5B7 London, Canada
| | - Mikko Karttunen
- Centre
for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, N6A 5B7 London, Canada
- Department
of Physics & Astronomy, The University
of Western Ontario, N6A
5B7 London, Canada
- Department
of Chemistry, The University of Western
Ontario, N6A 5B7 London, Canada
| | - Bert L. de Groot
- Computational
Biomolecular Dynamics Group, Department of Theoretical and Computational
Biophysics, Max Planck Institute for Multidisciplinary
Sciences, 37077 Göttingen, Germany
| | - Vytautas Gapsys
- Computational
Biomolecular Dynamics Group, Department of Theoretical and Computational
Biophysics, Max Planck Institute for Multidisciplinary
Sciences, 37077 Göttingen, Germany
- Computational
Chemistry, Janssen Research & Development, Janssen Pharmaceutica N. V., Turnhoutseweg 30, B-2340 Beerse, Belgium
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8
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Hussein A, Fan S, Lopez-Redondo M, Kenney I, Zhang X, Beckstein O, Stokes DL. Energy coupling and stoichiometry of Zn 2+/H + antiport by the prokaryotic cation diffusion facilitator YiiP. eLife 2023; 12:RP87167. [PMID: 37906094 PMCID: PMC10617992 DOI: 10.7554/elife.87167] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023] Open
Abstract
YiiP from Shewanella oneidensis is a prokaryotic Zn2+/H+ antiporter that serves as a model for the Cation Diffusion Facilitator (CDF) superfamily, members of which are generally responsible for homeostasis of transition metal ions. Previous studies of YiiP as well as related CDF transporters have established a homodimeric architecture and the presence of three distinct Zn2+ binding sites named A, B, and C. In this study, we use cryo-EM, microscale thermophoresis and molecular dynamics simulations to address the structural and functional roles of individual sites as well as the interplay between Zn2+ binding and protonation. Structural studies indicate that site C in the cytoplasmic domain is primarily responsible for stabilizing the dimer and that site B at the cytoplasmic membrane surface controls the structural transition from an inward facing conformation to an occluded conformation. Binding data show that intramembrane site A, which is directly responsible for transport, has a dramatic pH dependence consistent with coupling to the proton motive force. A comprehensive thermodynamic model encompassing Zn2+ binding and protonation states of individual residues indicates a transport stoichiometry of 1 Zn2+ to 2-3 H+ depending on the external pH. This stoichiometry would be favorable in a physiological context, allowing the cell to use the proton gradient as well as the membrane potential to drive the export of Zn2+.
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Affiliation(s)
- Adel Hussein
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
| | - Shujie Fan
- Department of Physics, Arizona State UniversityTempeUnited States
| | - Maria Lopez-Redondo
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
| | - Ian Kenney
- Department of Physics, Arizona State UniversityTempeUnited States
| | - Xihui Zhang
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
| | - Oliver Beckstein
- Department of Physics, Arizona State UniversityTempeUnited States
| | - David L Stokes
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
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9
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Olgenblum GI, Carmon N, Harries D. Not Always Sticky: Specificity of Protein Stabilization by Sugars Is Conferred by Protein-Water Hydrogen Bonds. J Am Chem Soc 2023; 145:23308-23320. [PMID: 37845197 PMCID: PMC10603812 DOI: 10.1021/jacs.3c08702] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Solutes added to buffered solutions directly impact protein folding. Protein stabilization by cosolutes or crowders has been shown to be largely driven by protein-cosolute volume exclusion complemented by chemical and soft interactions. By contrast to previous studies that indicate the invariably destabilizing role of soft protein-sugar attractions, we show here that soft interactions with sugar cosolutes are protein-specific and can be stabilizing or destabilizing. We experimentally follow the folding of two model miniproteins that are only marginally stable but in the presence of sugars and polyols fold into representative and distinct secondary structures: β-hairpin or α-helix. Our mean-field model reveals that while protein-sugar excluded volume interactions have a similar stabilizing effect on both proteins, the soft interactions add a destabilizing contribution to one miniprotein but further stabilize the other. Using molecular dynamics simulations, we link the soft protein-cosolute interactions to the weakening of direct protein-water hydrogen bonding due to the presence of sugars. Although these weakened hydrogen bonds destabilize both the native and denatured states of the two proteins, the resulting contribution to the folding free energy can be positive or negative depending on the amino acid sequence. This study indicates that the significant variation between proteins in their soft interactions with sugar determines the specific response of different proteins, even to the same sugar.
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Affiliation(s)
- Gil I Olgenblum
- The Fritz Haber Research Center, and the Harvey M. Kruger Center for Nanoscience & Nanotechnology, Institute of Chemistry, The Hebrew University, Jerusalem 9190401, Israel
| | - Neta Carmon
- The Fritz Haber Research Center, and the Harvey M. Kruger Center for Nanoscience & Nanotechnology, Institute of Chemistry, The Hebrew University, Jerusalem 9190401, Israel
| | - Daniel Harries
- The Fritz Haber Research Center, and the Harvey M. Kruger Center for Nanoscience & Nanotechnology, Institute of Chemistry, The Hebrew University, Jerusalem 9190401, Israel
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10
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Van Doren SR, Scott BS, Koppisetti RK. SARS-CoV-2 fusion peptide sculpting of a membrane with insertion of charged and polar groups. Structure 2023; 31:1184-1199.e3. [PMID: 37625399 PMCID: PMC10592393 DOI: 10.1016/j.str.2023.07.015] [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: 12/14/2022] [Revised: 07/10/2023] [Accepted: 07/31/2023] [Indexed: 08/27/2023]
Abstract
The fusion peptide of SARS-CoV-2 spike is essential for infection. How this charged and hydrophobic domain occupies and affects membranes needs clarification. Its depth in zwitterionic, bilayered micelles at pH 5 (resembling late endosomes) was measured by paramagnetic NMR relaxation enhancements used to bias molecular dynamics simulations. Asp830 inserted deeply, along with Lys825 or Lys835. Protonation of Asp830 appeared to enhance agreement of simulated and NMR-measured depths. While the fusion peptide occupied a leaflet of the DMPC bilayer, the opposite leaflet invaginated with influx of water and choline head groups in around Asp830 and bilayer-inserted polar side chains. NMR-detected hydrogen exchange found corroborating hydration of the backbone of Thr827-Phe833 inserted deeply in bicelles. Pinching of the membrane at the inserted charge and the intramembrane hydration of polar groups agree with theory. Formation of corridors of hydrated, inward-turned head groups was accompanied by flip-flop of head groups. Potential roles of the defects are discussed.
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Affiliation(s)
- Steven R Van Doren
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA; Institute for Data Science and Informatics, University of Missouri, Columbia, MO 65211, USA.
| | - Benjamin S Scott
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Rama K Koppisetti
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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11
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Li Y, Kim M, Pial TH, Lin Y, Cui H, Olvera de la Cruz M. Aggregation-Induced Asymmetric Charge States of Amino Acids in Supramolecular Nanofibers. J Phys Chem B 2023; 127:8176-8184. [PMID: 37721979 DOI: 10.1021/acs.jpcb.3c05598] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
Electrostatic interactions contribute critically to the kinetic pathways and thermodynamic outcomes of peptide self-assembly involving one or more than one charged amino acids. While it is well understood in protein folding that those amino acids with acidic/basic side chains could shift their pKas when placed in a hydrophobic microenvironment, to what extent aggregation of monomeric peptide units from the bulk solution could alter their charged status and how this change in pKa values would reciprocally impact their assembly outcomes. Here, we design and analyze two solution systems containing peptide amphiphiles with hydrocarbon chains of different lengths to determine the factor of deprotonation on assembly. Our results suggest that models of supramolecular nanofibers with uniformly distributed, fully charged amino acids are oversimplified. We demonstrate, with molecular dynamics simulations, and validate with experimental results that asymmetric, different protonation states of the peptides lead to distinct nanostructures after self-assembly. The results give estimates on the electrostatic interactions in peptide amphiphiles required for their self-assembly and shed light on modeling molecular assembly systems containing charged amino acids.
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Affiliation(s)
- Y Li
- Department of Chemical and Biomolecular Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Center of Computation and Theory of Soft Materials, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - M Kim
- Department of Chemical and Biomolecular Engineering and Institute for NanoBiotechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - T H Pial
- Center of Computation and Theory of Soft Materials, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
| | - Y Lin
- Center of Computation and Theory of Soft Materials, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - H Cui
- Department of Chemical and Biomolecular Engineering and Institute for NanoBiotechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
- Department of Oncology and Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - M Olvera de la Cruz
- Department of Chemical and Biomolecular Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Center of Computation and Theory of Soft Materials, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
- Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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12
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Ji Y, Liu D, Zhu H, Bao L, Chang R, Gao X, Yin J. Unstructured Polypeptides as a Versatile Drug Delivery Technology. Acta Biomater 2023; 164:74-93. [PMID: 37075961 DOI: 10.1016/j.actbio.2023.04.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/23/2023] [Accepted: 04/13/2023] [Indexed: 04/21/2023]
Abstract
Although polyethylene glycol (PEG), or "PEGylation" has become a widely applied approach for improving the efficiency of drug delivery, the immunogenicity and non-biodegradability of this synthetic polymer have prompted an evident need for alternatives. To overcome these caveats and to mimic PEG -or other natural or synthetic polymers- for the purpose of drug half-life extension, unstructured polypeptides are designed. Due to their tunable length, biodegradability, low immunogenicity and easy production, unstructured polypeptides have the potential to replace PEG as the preferred technology for therapeutic protein/peptide delivery. This review provides an overview of the evolution of unstructured polypeptides, starting from natural polypeptides to engineered polypeptides and discusses their characteristics. Then, it is described that unstructured polypeptides have been successfully applied to numerous drugs, including peptides, proteins, antibody fragments, and nanocarriers, for half-life extension. Innovative applications of unstructured peptides as releasable masks, multimolecular adaptors and intracellular delivery carriers are also discussed. Finally, challenges and future perspectives of this promising field are briefly presented. STATEMENT OF SIGNIFICANCE: : Polypeptide fusion technology simulating PEGylation has become an important topic for the development of long-circulating peptide or protein drugs without reduced activity, complex processes, and kidney injury caused by PEG modification. Here we provide a detailed and in-depth review of the recent advances in unstructured polypeptides. In addition to the application of enhanced pharmacokinetic performance, emphasis is placed on polypeptides as scaffolders for the delivery of multiple drugs, and on the preparation of reasonably designed polypeptides to manipulate the performance of proteins and peptides. This review will provide insight into future application of polypeptides in peptide or protein drug development and the design of novel functional polypeptides.
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Affiliation(s)
- Yue Ji
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals and State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China
| | - Dingkang Liu
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals and State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China
| | - Haichao Zhu
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals and State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China
| | - Lichen Bao
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing 210009, China
| | - Ruilong Chang
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals and State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China
| | - Xiangdong Gao
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals and State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
| | - Jun Yin
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals and State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
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13
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Foroutannejad S, Good LL, Lin C, Carter ZI, Tadesse MG, Lucius AL, Crane BR, Maillard RA. The cofactor-dependent folding mechanism of Drosophila cryptochrome revealed by single-molecule pulling experiments. Nat Commun 2023; 14:1057. [PMID: 36828841 PMCID: PMC9958137 DOI: 10.1038/s41467-023-36701-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 02/10/2023] [Indexed: 02/26/2023] Open
Abstract
The link between cofactor binding and protein activity is well-established. However, how cofactor interactions modulate folding of large proteins remains unknown. We use optical tweezers, clustering and global fitting to dissect the folding mechanism of Drosophila cryptochrome (dCRY), a 542-residue protein that binds FAD, one of the most chemically and structurally complex cofactors in nature. We show that the first dCRY parts to fold are independent of FAD, but later steps are FAD-driven as the remaining polypeptide folds around the cofactor. FAD binds to largely unfolded intermediates, yet with association kinetics above the diffusion-limit. Interestingly, not all FAD moieties are required for folding: whereas the isoalloxazine ring linked to ribitol and one phosphate is sufficient to drive complete folding, the adenosine ring with phosphates only leads to partial folding. Lastly, we propose a dCRY folding model where regions that undergo conformational transitions during signal transduction are the last to fold.
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Affiliation(s)
| | - Lydia L Good
- Department of Chemistry, Georgetown University, Washington, DC, USA
| | - Changfan Lin
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Zachariah I Carter
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Mahlet G Tadesse
- Department of Mathematics and Statistics, Georgetown University, Washington, DC, USA
| | - Aaron L Lucius
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brian R Crane
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, NY, USA
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14
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Liu Y, Liu J, He X. Different p Ka Shifts of Internal GLU8 in Human β-Endorphin Amyloid Revealing a Coupling of Internal Ionization and Stepwise Fibril Disassembly. J Phys Chem B 2023; 127:1089-1096. [PMID: 36696655 DOI: 10.1021/acs.jpcb.2c06706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
As a functional amyloid, human β-endorphin amyloid fibril features a β-solenoid conformation and store peptide hormones within acidic secretory granules, which would be released into the blood through fibril disassembly when the cellular milieu pH increases from acidic to neutral level on exocytosis. To gain detailed atomic mechanism of β-endorphin amyloid fibrils' pH-responsive disassembly, we conduct constant pH molecular dynamics simulations to investigate the structural and dynamical properties of β-endorphin amyloid fibrils in experiencing the environmental pH changes. Our results demonstrate a clear pKa shift of the internal ionizable residue of GLU8, and this shift becomes even more pronounced when it is buried more deeply in the amyloid fibrils. The unusual pKa of GLU8 reveals that its protonation state changes from the protonated state in the acidic secretory granule to the deprotonated state in the neutral pH conditions in the blood, where the deprotonation of GLU8 leads to unfavorable interactions within the hydrophobic core of the amyloid and subsequent fibril disassembly. The different pKa shifts of GLU8 relative to its positions in the amyloid fibril indicate that the β-endorphin amyloid fibril disassembly is a stepwise process, accounting for the experimental observation that the disassembly always initiates from the outermost layer. This study reveals the critical role of the protonation state of GLU8 in amyloid fibrils' pH-responsive disassembly, and provides clear insights for understanding the structural transitions of amyloids in hormone secretion. This study also provides theoretical basis for designing pH-sensitive biological tools for specific use with precise positioning of ionizable residues into the hydrophobic interior of proteins.
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Affiliation(s)
- Yiwei Liu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, China
| | - Jinfeng Liu
- Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Xiao He
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, China.,New York University-East China Normal University Center for Computational Chemistry, New York University Shanghai, Shanghai, 200062, China
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15
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Funk RHW, Scholkmann F. The significance of bioelectricity on all levels of organization of an organism. Part 1: From the subcellular level to cells. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 177:185-201. [PMID: 36481271 DOI: 10.1016/j.pbiomolbio.2022.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/24/2022] [Accepted: 12/03/2022] [Indexed: 12/12/2022]
Abstract
Bioelectricity plays an essential role in the structural and functional organization of biological organisms. In this first article of our three-part series, we summarize the importance of bioelectricity for the basic structural level of biological organization, i.e. from the subcellular level (charges, ion channels, molecules and cell organelles) to cells.
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Affiliation(s)
- Richard H W Funk
- Institute of Anatomy, Center for Theoretical Medicine, TU-Dresden, 01307, Dresden, Germany; Dresden International University, 01067, Dresden, Germany.
| | - Felix Scholkmann
- Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091, Zurich, Switzerland.
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16
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Kloes G, Bennett TJD, Chapet-Batlle A, Behjatian A, Turberfield AJ, Krishnan M. Far-Field Electrostatic Signatures of Macromolecular 3D Conformation. NANO LETTERS 2022; 22:7834-7840. [PMID: 36125326 PMCID: PMC9562458 DOI: 10.1021/acs.nanolett.2c02485] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In solution as in vacuum, the electrostatic field distribution in the vicinity of a charged object carries information on its three-dimensional geometry. We report on an experimental study exploring the effect of molecular shape on long-range electrostatic interactions in solution. Working with DNA nanostructures carrying approximately equal amounts of total charge but each in a different three-dimensional conformation, we demonstrate that the geometry of the distribution of charge in a molecule has substantial impact on its electrical interactions. For instance, a tetrahedral structure, which is the most compact distribution of charge we tested, can create a far-field effect that is effectively identical to that of a rod-shaped molecule carrying half the amount of total structural charge. Our experiments demonstrate that escape-time electrometry (ETe) furnishes a rapid and facile method to screen and identify 3D conformations of charged biomolecules or molecular complexes in solution.
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Affiliation(s)
- Gunnar Kloes
- Physical
and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Timothy J. D. Bennett
- Physical
and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Alma Chapet-Batlle
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Parks Road, Oxford OX1
3PU, United Kingdom
| | - Ali Behjatian
- Physical
and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Andrew J. Turberfield
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Parks Road, Oxford OX1
3PU, United Kingdom
- The Kavli
Institute for Nanoscience Discovery, Sherrington Road, Oxford OX1 3QU, United Kingdom
| | - Madhavi Krishnan
- Physical
and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
- The Kavli
Institute for Nanoscience Discovery, Sherrington Road, Oxford OX1 3QU, United Kingdom
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17
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Chu AE, Fernandez D, Liu J, Eguchi RR, Huang PS. De Novo Design of a Highly Stable Ovoid TIM Barrel: Unlocking Pocket Shape towards Functional Design. BIODESIGN RESEARCH 2022; 2022:9842315. [PMID: 37850141 PMCID: PMC10521652 DOI: 10.34133/2022/9842315] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/26/2022] [Indexed: 10/19/2023] Open
Abstract
The ability to finely control the structure of protein folds is an important prerequisite to functional protein design. The TIM barrel fold is an important target for these efforts as it is highly enriched for diverse functions in nature. Although a TIM barrel protein has been designed de novo, the ability to finely alter the curvature of the central beta barrel and the overall architecture of the fold remains elusive, limiting its utility for functional design. Here, we report the de novo design of a TIM barrel with ovoid (twofold) symmetry, drawing inspiration from natural beta and TIM barrels with ovoid curvature. We use an autoregressive backbone sampling strategy to implement our hypothesis for elongated barrel curvature, followed by an iterative enrichment sequence design protocol to obtain sequences which yield a high proportion of successfully folding designs. Designed sequences are highly stable and fold to the designed barrel curvature as determined by a 2.1 Å resolution crystal structure. The designs show robustness to drastic mutations, retaining high melting temperatures even when multiple charged residues are buried in the hydrophobic core or when the hydrophobic core is ablated to alanine. As a scaffold with a greater capacity for hosting diverse hydrogen bonding networks and installation of binding pockets or active sites, the ovoid TIM barrel represents a major step towards the de novo design of functional TIM barrels.
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Affiliation(s)
- Alexander E. Chu
- Biophysics Program, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Daniel Fernandez
- Program in Chemistry, Engineering, And Medicine for Human Health (ChEM-H), Stanford University, Stanford, CA, USA
- Stanford ChEM-H, Macromolecular Structure Knowledge Center, Stanford University, Stanford, CA, USA
| | - Jingjia Liu
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Raphael R. Eguchi
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Stanford ChEM-H, Macromolecular Structure Knowledge Center, Stanford University, Stanford, CA, USA
- Department of Biochemistry, Stanford University, Stanford, CA, USA
| | - Po-Ssu Huang
- Biophysics Program, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Stanford ChEM-H, Macromolecular Structure Knowledge Center, Stanford University, Stanford, CA, USA
- Bio-X Institute, Stanford University, Stanford, CA, USA
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18
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Romero ML, Garcia Seisdedos H, Ibarra‐Molero B. Active site center redesign increases protein stability preserving catalysis in thioredoxin. Protein Sci 2022. [PMCID: PMC9601870 DOI: 10.1002/pro.4417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The stabilization of natural proteins is a long‐standing desired goal in protein engineering. Optimizing the hydrophobicity of the protein core often results in extensive stability enhancements. However, the presence of totally or partially buried catalytic charged residues, essential for protein function, has limited the applicability of this strategy. Here, focusing on the thioredoxin, we aimed to augment protein stability by removing buried charged residues in the active site without loss of catalytic activity. To this end, we performed a charged‐to‐hydrophobic substitution of a buried and functional group, resulting in a significant stability increase yet abolishing catalytic activity. Then, to simulate the catalytic role of the buried ionizable group, we designed a combinatorial library of variants targeting a set of seven surface residues adjacent to the active site. Notably, more than 50% of the library variants restored, to some extent, the catalytic activity. The combination of experimental study of 2% of the library with the prediction of the whole mutational space by partial least squares regression revealed that a single point mutation at the protein surface is sufficient to fully restore the catalytic activity without thermostability cost. As a result, we engineered one of the highest thermal stabilities reported for a protein with a natural occurring fold (137°C). Further, our hyperstable variant preserves the catalytic activity both in vitro and in vivo.
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Affiliation(s)
- Maria Luisa Romero
- Departamento de Química Física Universidad de Granada Granada
- Max Planck Institute of Molecular Cell Biology and Genetics Dresden Germany
- Center for Systems Biology Dresden Dresden Germany
| | - Hector Garcia Seisdedos
- Departamento de Química Física Universidad de Granada Granada
- Department of Structural Biology Weizmann Institute of Science Rehovot Israel
- Department of Structural Biology Instituto de Biologia Molecular de Barcelona (IBMB‐CSIC) Barcelona Spain
| | - Beatriz Ibarra‐Molero
- Departamento de Química Física Universidad de Granada Granada
- Department of Structural Biology Instituto de Biologia Molecular de Barcelona (IBMB‐CSIC) Barcelona Spain
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19
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Affiliation(s)
- Vaishali Thakkur
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Chandan Kumar Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Nisanth N. Nair
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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20
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Lincon A, Das S, DasGupta S. Capturing protein denaturation using electrical impedance technique. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Li T, Yu L, Sun J, Liu J, He X. Ionization of D571 Is Coupled with SARS-CoV-2 Spike Up/Down Equilibrium Revealing the pH-Dependent Allosteric Mechanism of Receptor-Binding Domains. J Phys Chem B 2022; 126:4828-4839. [PMID: 35736566 PMCID: PMC9236204 DOI: 10.1021/acs.jpcb.2c02365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/05/2022] [Indexed: 11/30/2022]
Abstract
As a type I viral fusion protein, SARS-CoV-2 spike undergoes a pH-dependent switch to mediate the endosomal positioning of the receptor-binding domain to facilitate viral entry into cells and immune evasion. Gaps in our knowledge concerning the conformational transitions and key intramolecular motivations have hampered the development of effective therapeutics against the virus. To clarify the pH-sensitive elements on spike-gating the receptor-binding domain (RBD) opening and understand the details of the RBD opening transition, we performed microsecond-time scale constant pH molecular dynamics simulations in this study. We identified the deeply buried D571 with a clear pKa shift, suggesting a potential pH sensor, and showed the coupling of ionization of D571 with spike RBD-up/down equilibrium. We also computed the free-energy landscape for RBD opening and identified the crucial interactions that influence RBD dynamics. The atomic-level characterization of the pH-dependent spike activation mechanism provided herein offers new insights for a better understanding of the fundamental mechanisms of SARS-CoV-2 viral entry and infection and hence supports the discovery of novel therapeutics for COVID-19.
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Affiliation(s)
- Tong Li
- School of Traditional Chinese Pharmacy,
China Pharmaceutical University, Nanjing 210009,
China
| | - Lan Yu
- School of Science, China Pharmaceutical
University, Nanjing 210009, China
| | - Jingfang Sun
- School of Basic Medicine and Clinical Pharmacy,
China Pharmaceutical University, Nanjing 210009,
China
| | - Jinfeng Liu
- School of Basic Medicine and Clinical Pharmacy,
China Pharmaceutical University, Nanjing 210009,
China
| | - Xiao He
- Shanghai Engineering Research Center of Molecular
Therapeutics and New Drug Development, Shanghai Frontiers Science Center of Molecule
Intelligent Syntheses, School of Chemistry and Molecular Engineering, East
China Normal University, Shanghai 200062, China
- New York University-East China Normal University
Center for Computational Chemistry, New York University
Shanghai, Shanghai 200062, China
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22
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Chen AY, Lee J, Damjanovic A, Brooks BR. Protein p Ka Prediction by Tree-Based Machine Learning. J Chem Theory Comput 2022; 18:2673-2686. [PMID: 35289611 PMCID: PMC10510853 DOI: 10.1021/acs.jctc.1c01257] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protonation states of ionizable protein residues modulate many essential biological processes. For correct modeling and understanding of these processes, it is crucial to accurately determine their pKa values. Here, we present four tree-based machine learning models for protein pKa prediction. The four models, Random Forest, Extra Trees, eXtreme Gradient Boosting (XGBoost), and Light Gradient Boosting Machine (LightGBM), were trained on three experimental PDB and pKa datasets, two of which included a notable portion of internal residues. We observed similar performance among the four machine learning algorithms. The best model trained on the largest dataset performs 37% better than the widely used empirical pKa prediction tool PROPKA and 15% better than the published result from the pKa prediction method DelPhiPKa. The overall root-mean-square error (RMSE) for this model is 0.69, with surface and buried RMSE values being 0.56 and 0.78, respectively, considering six residue types (Asp, Glu, His, Lys, Cys, and Tyr), and 0.63 when considering Asp, Glu, His, and Lys only. We provide pKa predictions for proteins in human proteome from the AlphaFold Protein Structure Database and observed that 1% of Asp/Glu/Lys residues have highly shifted pKa values close to the physiological pH.
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Affiliation(s)
- Ada Y. Chen
- Department of Physics & Astronomy, Johns Hopkins
University, Baltimore, Maryland, 21218
- Laboratory of Computational Biology, National Heart, Lung
and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892
| | - Juyong Lee
- Department of Chemistry, Division of Chemistry and
Biochemistry, Kangwon National University, 1 Gangwondaehak-gil, Chuncheon, 24341,
Republic of Korea
| | - Ana Damjanovic
- Department of Biophysics, Johns Hopkins University,
Baltimore, Maryland, 21218
| | - Bernard R. Brooks
- Laboratory of Computational Biology, National Heart, Lung
and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892
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23
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Mozo-Villarías A, Cedano JA, Querol E. The use of vector formalism in the analysis of hydrophobic and electric driving forces in biological assemblies. Q Rev Biophys 2022; 55:1-50. [PMID: 35400352 DOI: 10.1017/s0033583522000038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Hydrophobic forces are known to have a crucial part not only in the conformation of the three-dimensional structure of proteins, but also in the build-up of DNA–protein complexes. Electric forces also play an important role both in the tertiary as well in the quaternary structure of macromolecular associations. Sometimes both hydrophobic and electric interactions add up their strengths to accomplish these structures but in most cases they act in opposite directions. This fact, together with being overall interactions with different ranges, provides a nuanced equilibrium also modulated by the need to comply with steric hindrances and geometric frustration effects. This review focuses on the utility of using the hydrophobic and electrical dipole moment vectors to describe the interactions that give rise to the structures of biological macromolecules. Although different definitions of both electric dipole and hydrophobic moments have been described in the literature, results obtained in biological assemblies demonstrate the principle of the biological membrane model. According to this model, postulated by our group, biological macromolecules tend to associate by aligning their hydrophobic moments in a similar manner to phospholipids in a membrane. Examples of both closed and open structures are used to assess the predictability of our model. We seek agreement between our results with those described in the current literature. The review ends with possible future projections using this formalism.
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Affiliation(s)
- Angel Mozo-Villarías
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Campus de Bellaterra, Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Juan A Cedano
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Campus de Bellaterra, Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Enrique Querol
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Campus de Bellaterra, Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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24
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Sakari M, Tran MT, Rossjohn J, Pulliainen AT, Beddoe T, Littler DR. Crystal structures of pertussis toxin with NAD+ and analogs provide structural insights into the mechanism of its cytosolic ADP-ribosylation activity. J Biol Chem 2022; 298:101892. [PMID: 35378130 PMCID: PMC9079181 DOI: 10.1016/j.jbc.2022.101892] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 11/19/2022] Open
Abstract
Bordetella pertussis is the causative agent of whooping cough, a highly contagious respiratory disease. Pertussis toxin (PT), a major virulence factor secreted by B. pertussis, is an AB5-type protein complex topologically related to cholera toxin. The PT protein complex is internalized by host cells and follows a retrograde trafficking route to the endoplasmic reticulum, where it subsequently dissociates. The released enzymatic S1 subunit is then translocated from the endoplasmic reticulum into the cytosol and subsequently ADP-ribosylates the inhibitory alpha-subunits (Gαi) of heterotrimeric G proteins, thus promoting dysregulation of G protein–coupled receptor signaling. However, the mechanistic details of the ADP-ribosylation activity of PT are not well understood. Here, we describe crystal structures of the S1 subunit in complex with nicotinamide adenine dinucleotide (NAD+), with NAD+ hydrolysis products ADP-ribose and nicotinamide, with NAD+ analog PJ34, and with a novel NAD+ analog formed upon S1 subunit crystallization with 3-amino benzamide and NAD+, which we name benzamide amino adenine dinucleotide. These crystal structures provide unprecedented insights into pre- and post-NAD+ hydrolysis steps of the ADP-ribosyltransferase activity of PT. We propose that these data may aid in rational drug design approaches and further development of PT-specific small-molecule inhibitors.
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Affiliation(s)
- Moona Sakari
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Turku, Finland
| | - Mai T Tran
- Infection and Immunity Program & Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Jamie Rossjohn
- Infection and Immunity Program & Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Institute of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, Wales, United Kingdom
| | - Arto T Pulliainen
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Turku, Finland.
| | - Travis Beddoe
- Department of Animal, Plant and Soil Science and Centre for AgriBioscience, La Trobe University, Bundoora, Victoria, Australia.
| | - Dene R Littler
- Infection and Immunity Program & Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
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25
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Deng J, Cui Q. Electronic Polarization Is Essential for the Stabilization and Dynamics of Buried Ion Pairs in Staphylococcal Nuclease Mutants. J Am Chem Soc 2022; 144:4594-4610. [PMID: 35239338 PMCID: PMC9616648 DOI: 10.1021/jacs.2c00312] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Buried charged residues play important roles in the modulation of protein stabilities and conformational dynamics and make crucial contributions to protein functions. Considering the generally nonpolar nature of protein interior, a key question concerns the contribution of electronic polarization to the stabilization and properties of buried charges. We answer this question by conducting free energy simulations using the latest polarizable CHARMM force field based on Drude oscillators for a series of Staphylococcal nuclease mutants that involve a buried Glu-Lys pair in different titration states and orientations. While a nonpolarizable model suggests that the ionized form of the buried Glu-Lys pair is more than 40 kcal/mol less stable than the charge-neutral form, the two titration states are comparable in stability when electronic polarization is included explicitly, a result better reconcilable with available experimental data. Analysis of free energy components suggests that additional stabilization of the ionized Glu-Lys pair has contributions from both the enhanced salt-bridge strength and stronger interaction between the ion-pair and surrounding protein residues and penetrated water. Despite the stronger direct interaction between Glu and Lys, the ion-pair exhibits considerably larger and faster structural fluctuations when polarization is included, due to compensation of interactions in the cavity. Collectively, observations from this work provide compelling evidence that electronic polarization is essential to the stability, hydration, dynamics, and therefore function of buried charges in proteins. Therefore, our study advocates for the explicit consideration of electronic polarization for mechanistic and engineering studies that implicate buried charged residues, such as enzymes and ion transporters.
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Affiliation(s)
- Jiahua Deng
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Qiang Cui
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.,Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.,Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, Massachusetts 02215, United States
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26
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Zheng D, Nakabayashi M, Asano Y. Structural characterization of Linum usitatissimum hydroxynitrile lyase: A new cyanohydrin decomposition mechanism involving a cyano-zinc complex. J Biol Chem 2022; 298:101650. [PMID: 35101448 PMCID: PMC8892092 DOI: 10.1016/j.jbc.2022.101650] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 12/02/2022] Open
Abstract
Hydroxynitrile lyase from Linum usitatissimum (LuHNL) is an enzyme involved in the catabolism of cyanogenic glycosides to release hydrogen cyanide upon tissue damage. This enzyme strictly conserves the substrate- and NAD(H)-binding domains of Zn2+-containing alcohol dehydrogenase (ADH); however, there is no evidence suggesting that LuHNL possesses ADH activity. Herein, we determined the ligand-free 3D structure of LuHNL and its complex with acetone cyanohydrin and (R)-2-butanone cyanohydrin using X-ray crystallography. These structures reveal that an A-form NAD+ is tightly but not covalently bound to each subunit of LuHNL. The restricted movement of the NAD+ molecule is due to the “sandwich structure” on the adenine moiety of NAD+. Moreover, the structures and mutagenesis analysis reveal a novel reaction mechanism for cyanohydrin decomposition involving the cyano-zinc complex and hydrogen-bonded interaction of the hydroxyl group of cyanohydrin with Glu323/Thr65 and H2O/Lys162 of LuHNL. The deprotonated Lys162 and protonated Glu323 residues are presumably stabilized by a partially desolvated microenvironment. In summary, the substrate binding geometry of LuHNL provides insights into the differences in activities of LuHNL and ADH, and identifying this novel reaction mechanism is an important contribution to the study of hydroxynitrile lyases.
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Affiliation(s)
- Daijun Zheng
- Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University, Imizu, Toyama, Japan
| | - Makoto Nakabayashi
- Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi, Osaka, Japan
| | - Yasuhisa Asano
- Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University, Imizu, Toyama, Japan.
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27
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Bondar AN. Mechanisms of long-distance allosteric couplings in proton-binding membrane transporters. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:199-239. [PMID: 35034719 DOI: 10.1016/bs.apcsb.2021.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Membrane transporters that use proton binding and proton transfer for function couple local protonation change with changes in protein conformation and water dynamics. Changes of protein conformation might be required to allow transient formation of hydrogen-bond networks that bridge proton donor and acceptor pairs separated by long distances. Inter-helical hydrogen-bond networks adjust rapidly to protonation change, and ensure rapid response of the protein structure and dynamics. Membrane transporters with known three-dimensional structures and proton-binding groups inform on general principles of protonation-coupled protein conformational dynamics. Inter-helical hydrogen bond motifs between proton-binding carboxylate groups and a polar sidechain are observed in unrelated membrane transporters, suggesting common principles of coupling protonation change with protein conformational dynamics.
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Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Măgurele, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, Jülich, Germany.
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28
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Podgorski MN, Harbort JS, Lee JHZ, Nguyen GT, Bruning JB, Donald WA, Bernhardt PV, Harmer JR, Bell SG. An Altered Heme Environment in an Engineered Cytochrome P450 Enzyme Enables the Switch from Monooxygenase to Peroxygenase Activity. ACS Catal 2022. [DOI: 10.1021/acscatal.1c05877] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Matthew N. Podgorski
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Joshua S. Harbort
- Center for Advanced Imaging, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Joel H. Z. Lee
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Giang T.H. Nguyen
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - John B. Bruning
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - William A. Donald
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Paul V. Bernhardt
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jeffrey R. Harmer
- Center for Advanced Imaging, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Stephen G. Bell
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
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29
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Fossat MJ, Posey AE, Pappu RV. Quantifying charge state heterogeneity for proteins with multiple ionizable residues. Biophys J 2021; 120:5438-5453. [PMID: 34826385 PMCID: PMC8715249 DOI: 10.1016/j.bpj.2021.11.2886] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/03/2021] [Accepted: 11/19/2021] [Indexed: 01/07/2023] Open
Abstract
Ionizable residues can release and take up protons and this has an influence on protein structure and function. The extent of protonation is linked to the overall pH of the solution and the local environments of ionizable residues. Binding or unbinding of a single proton generates a distinct charge microstate defined by a specific pattern of charges. Accordingly, the overall partition function is a sum over all charge microstates and Boltzmann weights of all conformations associated with each of the charge microstates. This ensemble-of-ensembles description recast as a q-canonical ensemble allows us to analyze and interpret potentiometric titrations that provide information regarding net charge as a function of pH. In the q-canonical ensemble, charge microstates are grouped into mesostates where each mesostate is a collection of microstates of the same net charge. Here, we show that leveraging the structure of the q-canonical ensemble allows us to decouple contributions of net proton binding and release from proton arrangement and conformational considerations. Through application of the q-canonical formalism to analyze potentiometric measurements of net charge in proteins with repetitive patterns of Lys and Glu residues, we determine the underlying mesostate pKa values and, more importantly, we estimate relative mesostate populations as a function of pH. This is a strength of using the q-canonical approach that cannot be replicated using purely site-specific analyses. Overall, our work shows how measurements of charge equilibria, decoupled from measurements of conformational equilibria, and analyzed using the framework of the q-canonical ensemble, provide protein-specific quantitative descriptions of pH-dependent populations of mesostates. This method is of direct relevance for measuring and understanding how different charge states contribute to conformational, binding, and phase equilibria of proteins.
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Affiliation(s)
- Martin J Fossat
- Department of Biomedical Engineering and Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri
| | - Ammon E Posey
- Department of Biomedical Engineering and Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri
| | - Rohit V Pappu
- Department of Biomedical Engineering and Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri.
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30
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Liu Y, Zhang Y, Sun Y, Ding F. A buried glutamate in the cross-β core renders β-endorphin fibrils reversible. NANOSCALE 2021; 13:19593-19603. [PMID: 34812835 PMCID: PMC8674924 DOI: 10.1039/d1nr05679d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Functional amyloids are abundant in living organisms from prokaryotes to eukaryotes playing diverse biological roles. In contrast to the irreversible aggregation of most known pathological amyloids, we postulate that naturally-occurring functional amyloids are reversible under evolutionary pressure to be able to modulate the fibrillization process, reuse the composite peptides, or perform their biological functions. β-Endorphin, an endogenous opioid peptide hormone, forms such kinds of reversible amyloid fibrils in secretory granules for efficient storage and returns to the functional state of monomers upon release into the blood. The environmental change between low pH in secretory granules and neutral pH in extracellular spaces is believed to drive the reversible fibrillization of β-endorphin. Here, we investigate the critical role of a buried glutamate, Glu8, in the pH-responsive disassembly of β-endorphin fibrils using all-atom molecular dynamics simulations along with structure-based pKa prediction. The fibril was stable at pH 5.5 or lower with all the buried Glu8 residues protonated and neutrally charged. After switching to neutral pH, the Glu8 residues of peptides at the outer layers of the ordered fibrils became deprotonated due to partial solvent exposure, causing sheet-to-coil conformational changes and subsequent exposure of adjacent Glu8 residues in the inner chains. Via iterative deprotonation of Glu8 and induced structural disruption, all Glu8 residues would be progressively deprotonated. Electrostatic repulsion between deprotonated Glu8 residues along with their high solvation tendency disrupted the hydrogen bonding between the β1 strands and increased the solvent exposure of those otherwise buried residues in the cross-β core. Overall, our computational study reveals that the strategic positioning of ionizable residues into the cross-β core is a potential approach for designing reversible amyloid fibrils as pH-responsive smart bio-nanomaterials.
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Affiliation(s)
- Yuying Liu
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Yu Zhang
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Yunxiang Sun
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA.
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA.
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31
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Frazee N, Mertz B. Intramolecular interactions play key role in stabilization of pHLIP at acidic conditions. J Comput Chem 2021; 42:1809-1816. [PMID: 34245047 DOI: 10.1002/jcc.26719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/30/2021] [Accepted: 06/21/2021] [Indexed: 12/12/2022]
Abstract
The pH-Low Insertion Peptide (pHLIP) is a membrane-active peptide that spontaneously folds into a transmembrane α-helix upon acidification. This activity enables pHLIP to potentially act as a vector for drugs related to diseases characterized by acidosis such as cancer or heart ischemia. Presently, due to aggregation-based effects, formulations of pHLIP are only viable at near-μM concentrations. In addition, since most of pHLIP's measurable qualities involve a membrane, probing the details of pHLIP in the interstitial region is difficult. In attempts to shed light on these issues, we performed constant pH molecular dynamics simulations on pHLIP as well as P20G, a variant with increased helicity, in solution at 0 and 150 mM NaCl over a broad range of pHs. In general, the addition of ions reduced the effective pKa of the acidic residues in pHLIP. P20G exhibits a higher helicity than pHLIP in general and is more compact than pHLIP at pH values under 4. In terms of charge effects, sodium cations localized predominantly to the C-terminus of the peptide with a high density of acidic residues. Additionally, the salt bridge between R11 and D14 is by far the most favored and particularly so with pHLIP at 150 mM NaCl. We expect that this approach will be a valuable tool to screen variants of pHLIP for favorable properties in solution, an aspect of pHLIP design that to this point has largely been neglected.
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Affiliation(s)
- Nicolas Frazee
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, USA
| | - Blake Mertz
- C. Eugene Bennett Department of Chemistry, West Virginia University, WVU Cancer Institute, Morgantown, West Virginia, USA
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32
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Sangji MH, Sai H, Chin SM, Lee SR, R Sasselli I, Palmer LC, Stupp SI. Supramolecular Interactions and Morphology of Self-Assembling Peptide Amphiphile Nanostructures. NANO LETTERS 2021; 21:6146-6155. [PMID: 34259001 DOI: 10.1021/acs.nanolett.1c01737] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The morphology of supramolecular peptide nanostructures is difficult to predict given their complex energy landscapes. We investigated peptide amphiphiles containing β-sheet forming domains that form twisted nanoribbons in water. We explained the morphology based on a balance between the energetically favorable packing of molecules in the center of the nanostructures, the unfavorable packing at the edges, and the deformations due to packing of twisted β-sheets. We find that morphological polydispersity of PA nanostructures is determined by peptide sequences, and the twisting of their internal β-sheets. We also observed a change in the supramolecular chirality of the nanostructures as the peptide sequence was modified, although only amino acids with l-configuration were used. Upon increasing charge repulsion between molecules, we observed a change in morphology to long cylinders and then rodlike fragments and spherical micelles. Understanding the self-assembly mechanisms of peptide amphiphiles into nanostructures should be useful to optimize their well-known functions.
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Affiliation(s)
- M Hussain Sangji
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Center for Bio-Inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Hiroaki Sai
- Simpson Querrey Institute, Northwestern University, 303 E Superior, Chicago, Illinois 60611, United States
- Center for Bio-Inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Stacey M Chin
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Sieun Ruth Lee
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, Illinois 60208, United States
| | - Ivan R Sasselli
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Simpson Querrey Institute, Northwestern University, 303 E Superior, Chicago, Illinois 60611, United States
| | - Liam C Palmer
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Simpson Querrey Institute, Northwestern University, 303 E Superior, Chicago, Illinois 60611, United States
- Center for Bio-Inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Samuel I Stupp
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Medicine, Northwestern University, 676 N St. Clair, Chicago, Illinois 60611, United States
- Simpson Querrey Institute, Northwestern University, 303 E Superior, Chicago, Illinois 60611, United States
- Center for Bio-Inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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33
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Deng J, Cui Q. Reverse Protonation of Buried Ion-Pairs in Staphylococcal Nuclease Mutants. J Chem Theory Comput 2021; 17:4550-4563. [PMID: 34143626 DOI: 10.1021/acs.jctc.1c00355] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Although buried titratable residues in protein cavities are often of major functional importance, it is generally challenging to understand their properties such as the ionization state and factors of stabilization based on experimental studies alone. A specific set of examples involve buried Glu-Lys pairs in a series of variants of Staphylococcal nuclease, for which recent structural and thermodynamic studies appeared to suggest that both the stability and the ionization state of the buried Glu-Lys pair are sensitive to its orientation (i.e., Glu23-Lys36 vs Lys23-Glu36). To further clarify the situation, especially ionization states of the buried Glu-Lys pairs, we have conducted extensive molecular dynamics simulations and free energy computations. Microsecond molecular dynamics simulations show that the hydration level of the cavity depends on the orientation of the buried ion-pair therein as well as its ionization state; free energy simulations recapitulate the relative stability of Glu23-Lys36 (EK) vs Lys23-Glu36 (KE) mutants measured experimentally, although the difference is similar in magnitude regardless of the ionization state of the Glu-Lys pair. A complementary set of free energy simulations strongly suggests that, in contrast to the original suggestion in the experimental analysis, the Glu and Lys residues prefer to adopt their charge-neutral rather than the ionized states. This result is consistent with the low dielectric constant computed for water in the cavity, which makes it difficult for the protein cavity to stabilize a pair of charged Glu-Lys residues, even with water penetration. The current study highlights the role of free energy simulations in understanding the ionization state of buried titratable residues and the relevant energetic contributions, forming the basis for the rational design of buried charge networks in proteins.
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Affiliation(s)
- Jiahua Deng
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Qiang Cui
- Departments of Chemistry, Physics, and Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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34
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The Molecular Basis for Escherichia coli O157:H7 Phage FAHEc1 Endolysin Function and Protein Engineering to Increase Thermal Stability. Viruses 2021; 13:v13061101. [PMID: 34207694 PMCID: PMC8228626 DOI: 10.3390/v13061101] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 02/02/2023] Open
Abstract
Bacteriophage-encoded endolysins have been identified as antibacterial candidates. However, the development of endolysins as mainstream antibacterial agents first requires a comprehensive biochemical understanding. This study defines the atomic structure and enzymatic function of Escherichia coli O157:H7 phage FAHEc1 endolysin, LysF1. Bioinformatic analysis suggests this endolysin belongs to the T4 Lysozyme (T4L)-like family of proteins and contains a highly conserved catalytic triad. We then solved the structure of LysF1 with x-ray crystallography to 1.71 Å. LysF1 was confirmed to exist as a monomer in solution by sedimentation velocity experiments. The protein architecture of LysF1 is conserved between T4L and related endolysins. Comparative analysis with related endolysins shows that the spatial orientation of the catalytic triad is conserved, suggesting the catalytic mechanism of peptidoglycan degradation is the same as that of T4L. Differences in the sequence illustrate the role coevolution may have in the evolution of this fold. We also demonstrate that by mutating a single residue within the hydrophobic core, the thermal stability of LysF1 can be increased by 9.4 °C without compromising enzymatic activity. Overall, the characterization of LysF1 provides further insight into the T4L-like class of endolysins. Our study will help advance the development of related endolysins as antibacterial agents, as rational engineering will rely on understanding mutable positions within this protein fold.
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35
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Xu FY, Wen QH, Wang R, Li J, Chen BR, Zeng XA. Enhanced synthesis of succinylated whey protein isolate by pulsed electric field pretreatment. Food Chem 2021; 363:129892. [PMID: 34120044 DOI: 10.1016/j.foodchem.2021.129892] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 04/07/2021] [Accepted: 04/07/2021] [Indexed: 10/21/2022]
Abstract
The objective of this study was to investigate the feasibility of pulse electric field (PEF) as a pretreatment for whey protein isolate (WPI) before its succinylation. The degree of succinylation (DS) of WPI increased from 88.31% for native WPI to 93.45% for PEF-pretreated WPI (PWPI, initial pH 10.0) for the same succinic anhydride (SA) to WPI ratio (1:1). Fourier transform infrared spectroscopy and scanning electron microscopy analysis proved the successful succinylation of WPI. For PWPIs, the surface hydrophobicity, exposed sulphydryl, and total sulphydryl decreased, which indicates the occurrence of changes in protein structures with more hydrophilic groups and better protein dispersion. Moreover, PEF may expose more amino acid residues binding sites that are present inside the protein, which is more suitable for succinylation. Therefore, the PEF pretreatment of proteins can improve their efficient use that is expected to play a critical role in succinylation industry.
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Affiliation(s)
- Fei-Yue Xu
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, China
| | - Qing-Hui Wen
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, China; School of Chemistry, The University of Melbourne, Parkville, Victoria, Australia
| | - Rui Wang
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, China
| | - Jian Li
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, China
| | - Bo-Ru Chen
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, China
| | - Xin-An Zeng
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, China.
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36
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Lan W, Valente JJ, Ilott A, Chennamsetty N, Liu Z, Rizzo JM, Yamniuk AP, Qiu D, Shackman HM, Bolgar MS. Investigation of anomalous charge variant profile reveals discrete pH-dependent conformations and conformation-dependent charge states within the CDR3 loop of a therapeutic mAb. MAbs 2021; 12:1763138. [PMID: 32432964 PMCID: PMC7299213 DOI: 10.1080/19420862.2020.1763138] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During the development of a therapeutic monoclonal antibody (mAb-1), the charge variant profile obtained by pH-gradient cation exchange chromatography (CEX) contained two main peaks, each of which exhibited a unique intrinsic fluorescence profile and demonstrated inter-convertibility upon reinjection of isolated peak fractions. Domain analysis of mAb-1 by CEX and liquid chromatography-mass spectrometry indicated that the antigen-binding fragment chromatographed as two separate peaks that had identical mass. Surface plasmon resonance binding analysis to antigen demonstrated comparable kinetics/affinity between these fractionated peaks and unfractionated starting material. Subsequent molecular modeling studies revealed that the relatively long and flexible complementarity-determining region 3 (CDR3) loop on the heavy chain could adopt two discrete pH-dependent conformations: an “open” conformation at neutral pH where the HC-CDR3 is largely solvent exposed, and a “closed” conformation at lower pH where the solvent exposure of a neighboring tryptophan in the light chain is reduced and two aspartic acid residues near the ends of the HC-CDR3 loop have atypical pKa values. The pH-dependent equilibrium between “open” and “closed” conformations of the HC-CDR3, and its proposed role in the anomalous charge variant profile of mAb-1, were supported by further CEX and hydrophobic interaction chromatography studies. This work is an example of how pH-dependent conformational changes and conformation-dependent changes to net charge can unexpectedly contribute to perceived instability and require thorough analytical, biophysical, and functional characterization during biopharmaceutical drug product development.
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Affiliation(s)
- Wenkui Lan
- Drug Product Development, Bristol Myers Squibb, New Brunswick, United States
| | - Joseph J Valente
- Drug Product Development, Bristol Myers Squibb, New Brunswick, United States
| | - Andrew Ilott
- Drug Product Development, Bristol Myers Squibb, New Brunswick, United States
| | - Naresh Chennamsetty
- Biophysics Center of Excellence, Global Product Development and Supply, Bristol Myers Squibb, New Brunswick, United States
| | - Zhihua Liu
- Drug Product Development, Bristol Myers Squibb, New Brunswick, United States
| | - Joseph M Rizzo
- Discovery Biotherapeutics, Bristol Myers Squibb, Pennington, United States
| | - Aaron P Yamniuk
- Discovery Biotherapeutics, Bristol Myers Squibb, Pennington, United States
| | - Difei Qiu
- Chemical Process Department, Bristol Myers Squibb, New Brunswick, United States
| | - Holly M Shackman
- Chemical Process Department, Bristol Myers Squibb, New Brunswick, United States
| | - Mark S Bolgar
- Drug Product Development, Bristol Myers Squibb, New Brunswick, United States
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37
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A pH-dependent protein stability switch coupled to the perturbed pKa of a single ionizable residue. Biophys Chem 2021; 274:106591. [PMID: 33895555 DOI: 10.1016/j.bpc.2021.106591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/15/2021] [Accepted: 04/07/2021] [Indexed: 12/31/2022]
Abstract
The contribution of electrostatic interactions in protein stability has not been fully understood. Burial of an ionizable amino acid inside the hydrophobic protein core can affect its ionization equilibrium and shift its pKa differentially in the native (N) and unfolded (U) states of a protein and this coupling between the folding/unfolding cycle and the ionization equilibria of the ionizable residue can substantially influence the protein stability. Here, we studied the coupling of the folding/unfolding cycle with the ionization of a buried ionizable residue in a multi-domain protein, Human Serum Albumin (HSA) using fluorescence spectroscopy. A pH-dependent change in the stability of HSA was observed in the near native pH range (pH 6.0-9.0). The protonation-deprotonation equilibrium of a single thiol residue that is buried in the protein structure was identified to give rise to the pH-dependent protein stability. We quantified the pKa of the thiol residue in the N and the U states. The mean pKa of the thiol in the N state was upshifted by 0.5 units to 8.7 due to the burial of the thiol in the protein structure. Surprisingly, the mean pKa of the thiol in the U state was observed to be downshifted by 1.3 units to 6.9. These results indicate that some charged residues are spatially proximal to the thiol group in the U state. Our results suggest that, in addition to the N state, electrostatic interactions in the U state are important determinants of protein stability.
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38
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Molecular Mechanism of Nramp-Family Transition Metal Transport. J Mol Biol 2021; 433:166991. [PMID: 33865868 DOI: 10.1016/j.jmb.2021.166991] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 02/06/2023]
Abstract
The Natural resistance-associated macrophage protein (Nramp) family of transition metal transporters enables uptake and trafficking of essential micronutrients that all organisms must acquire to survive. Two decades after Nramps were identified as proton-driven, voltage-dependent secondary transporters, multiple Nramp crystal structures have begun to illustrate the fine details of the transport process and provide a new framework for understanding a wealth of preexisting biochemical data. Here we review the relevant literature pertaining to Nramps' biological roles and especially their conserved molecular mechanism, including our updated understanding of conformational change, metal binding and transport, substrate selectivity, proton transport, proton-metal coupling, and voltage dependence. We ultimately describe how the Nramp family has adapted the LeuT fold common to many secondary transporters to provide selective transition-metal transport with a mechanism that deviates from the canonical model of symport.
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39
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Beecroft SJ, Ayala M, McGillivray G, Nanda V, Agolini E, Novelli A, Digilio MC, Dotta A, Carrozzo R, Clayton J, Gaffney L, McLean CA, Ng J, Laing NG, Matteson P, Millonig J, Ravenscroft G. Biallelic hypomorphic variants in ALDH1A2 cause a novel lethal human multiple congenital anomaly syndrome encompassing diaphragmatic, pulmonary, and cardiovascular defects. Hum Mutat 2021; 42:506-519. [PMID: 33565183 DOI: 10.1002/humu.24179] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 12/05/2020] [Accepted: 12/31/2020] [Indexed: 12/11/2022]
Abstract
This study shows a causal association between ALDH1A2 variants and a novel, severe multiple congenital anomaly syndrome in humans that is neonatally lethal due to associated pulmonary hypoplasia and respiratory failure. In two families, exome sequencing identified compound heterozygous missense variants in ALDH1A2. ALDH1A2 is involved in the conversion of retinol (vitamin A) into retinoic acid (RA), which is an essential regulator of diaphragm and cardiovascular formation during embryogenesis. Reduced RA causes cardiovascular, diaphragmatic, and associated pulmonary defects in several animal models, matching the phenotype observed in our patients. In silico protein modeling showed probable impairment of ALDH1A2 for three of the four substitutions. In vitro studies show a reduction of RA. Few pathogenic variants in genes encoding components of the retinoic signaling pathway have been described to date, likely due to embryonic lethality. Thus, this study contributes significantly to knowledge of the role of this pathway in human diaphragm and cardiovascular development and disease. Some clinical features in our patients are also observed in Fryns syndrome (MIM# 229850), syndromic microphthalmia 9 (MIM# 601186), and DiGeorge syndrome (MIM# 188400). Patients with similar clinical features who are genetically undiagnosed should be tested for recessive ALDH1A2-deficient malformation syndrome.
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Affiliation(s)
- Sarah J Beecroft
- Faculty of Health and Medical Sciences, Centre of Medical Research, Harry Perkins Institute of Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Marcos Ayala
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, USA
| | - George McGillivray
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Women's Hospital, Melbourne, Australia
| | - Vikas Nanda
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| | - Emanuele Agolini
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, Rome, Italy
| | - Maria C Digilio
- Medical Genetics Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Andrea Dotta
- Division of Newborn Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Rosalba Carrozzo
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, Rome, Italy
| | - Joshua Clayton
- Faculty of Health and Medical Sciences, Centre of Medical Research, Harry Perkins Institute of Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Lydia Gaffney
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Women's Hospital, Melbourne, Australia
| | - Catriona A McLean
- Anatomical Pathology and Victorian Neuromuscular Laboratory Service, Alfred Health and Monash University, Melbourne, Victoria, Australia
| | - Jessica Ng
- Department of Anatomical Pathology, Royal Children's Hospital, Melbourne, Australia
| | - Nigel G Laing
- Faculty of Health and Medical Sciences, Centre of Medical Research, Harry Perkins Institute of Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Paul Matteson
- Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, USA
| | - James Millonig
- Department of Neuroscience and Cell Biology, Center for Advanced Biotechnology and Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| | - Gianina Ravenscroft
- Faculty of Health and Medical Sciences, Centre of Medical Research, Harry Perkins Institute of Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
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40
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Baumgart M, Röpke M, Mühlbauer ME, Asami S, Mader SL, Fredriksson K, Groll M, Gamiz-Hernandez AP, Kaila VRI. Design of buried charged networks in artificial proteins. Nat Commun 2021; 12:1895. [PMID: 33767131 PMCID: PMC7994573 DOI: 10.1038/s41467-021-21909-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 02/19/2021] [Indexed: 11/24/2022] Open
Abstract
Soluble proteins are universally packed with a hydrophobic core and a polar surface that drive the protein folding process. Yet charged networks within the central protein core are often indispensable for the biological function. Here, we show that natural buried ion-pairs are stabilised by amphiphilic residues that electrostatically shield the charged motif from its surroundings to gain structural stability. To explore this effect, we build artificial proteins with buried ion-pairs by combining directed computational design and biophysical experiments. Our findings illustrate how perturbation in charged networks can introduce structural rearrangements to compensate for desolvation effects. We validate the physical principles by resolving high-resolution atomic structures of the artificial proteins that are resistant towards unfolding at extreme temperatures and harsh chemical conditions. Our findings provide a molecular understanding of functional charged networks and how point mutations may alter the protein’s conformational landscape. Buried charged networks in proteins are often important for their biological functionality and are believed to destabilise the protein fold. Here, the authors combine computational design, MD simulations, biophysical experiments, NMR and X-ray crystallography to design and characterise artificial 4α-helical proteins with buried charged elements. They analyse their conformational landscapes and observe that the ion-pairs are stabilised by amphiphilic residues that electrostatically shield the charged motif, which increases structural stability.
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Affiliation(s)
- Mona Baumgart
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Michael Röpke
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Max E Mühlbauer
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Sam Asami
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Sophie L Mader
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Kai Fredriksson
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Michael Groll
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Ana P Gamiz-Hernandez
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany.,Department of Biochemistry and Biophysics, Stockholm University, 10691, Stockholm, Sweden
| | - Ville R I Kaila
- Center for Integrated Protein Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748, Garching, Germany. .,Department of Biochemistry and Biophysics, Stockholm University, 10691, Stockholm, Sweden.
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41
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Rowe JB, Kapolka NJ, Taghon GJ, Morgan WM, Isom DG. The evolution and mechanism of GPCR proton sensing. J Biol Chem 2021; 296:100167. [PMID: 33478938 PMCID: PMC7948426 DOI: 10.1074/jbc.ra120.016352] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/02/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022] Open
Abstract
Of the 800 G protein-coupled receptors (GPCRs) in humans, only three (GPR4, GPR65, and GPR68) regulate signaling in acidified microenvironments by sensing protons (H+). How these receptors have uniquely obtained this ability is unknown. Here, we show these receptors evolved the capability to sense H+ signals by acquiring buried acidic residues. Using our informatics platform pHinder, we identified a triad of buried acidic residues shared by all three receptors, a feature distinct from all other human GPCRs. Phylogenetic analysis shows the triad emerged in GPR65, the immediate ancestor of GPR4 and GPR68. To understand the evolutionary and mechanistic importance of these triad residues, we developed deep variant profiling, a yeast-based technology that utilizes high-throughput CRISPR to build and profile large libraries of GPCR variants. Using deep variant profiling and GPCR assays in HEK293 cells, we assessed the pH-sensing contributions of each triad residue in all three receptors. As predicted by our calculations, most triad mutations had profound effects consistent with direct regulation of receptor pH sensing. In addition, we found that an allosteric modulator of many class A GPCRs, Na+, synergistically regulated pH sensing by maintaining the pKa values of triad residues within the physiologically relevant pH range. As such, we show that all three receptors function as coincidence detectors of H+ and Na+. Taken together, these findings elucidate the molecular evolution and long-sought mechanism of GPR4, GPR65, and GPR68 pH sensing and provide pH-insensitive variants that should be valuable for assessing the therapeutic potential and (patho)physiological importance of GPCR pH sensing.
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Affiliation(s)
- Jacob B Rowe
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Nicholas J Kapolka
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Geoffrey J Taghon
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - William M Morgan
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Daniel G Isom
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA; The Department of Tumor Biology, University of Miami Sylvester Comprehensive Cancer Center, Miami, Florida, USA; The Institute for Data Science Computing, University of Miami, Coral Gables, Florida, USA.
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42
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Radka CD, Batte JL, Frank MW, Young BM, Rock CO. Structure and mechanism of Staphylococcus aureus oleate hydratase (OhyA). J Biol Chem 2021; 296:100252. [PMID: 33376139 PMCID: PMC7948970 DOI: 10.1074/jbc.ra120.016818] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/15/2020] [Accepted: 12/29/2020] [Indexed: 01/07/2023] Open
Abstract
Flavin adenine dinucleotide (FAD)-dependent bacterial oleate hydratases (OhyAs) catalyze the addition of water to isolated fatty acid carbon-carbon double bonds. Staphylococcus aureus uses OhyA to counteract the host innate immune response by inactivating antimicrobial unsaturated fatty acids. Mechanistic information explaining how OhyAs catalyze regiospecific and stereospecific hydration is required to understand their biological functions and the potential for engineering new products. In this study, we deduced the catalytic mechanism of OhyA from multiple structures of S. aureus OhyA in binary and ternary complexes with combinations of ligands along with biochemical analyses of relevant mutants. The substrate-free state shows Arg81 is the gatekeeper that controls fatty acid entrance to the active site. FAD binding engages the catalytic loop to simultaneously rotate Glu82 into its active conformation and Arg81 out of the hydrophobic substrate tunnel, allowing the fatty acid to rotate into the active site. FAD binding also dehydrates the active site, leaving a single water molecule connected to Glu82. This active site water is a hydronium ion based on the analysis of its hydrogen bond network in the OhyA•PEG400•FAD complex. We conclude that OhyA accelerates acid-catalyzed alkene hydration by positioning the fatty acid double bond to attack the active site hydronium ion, followed by the addition of water to the transient carbocation intermediate. Structural transitions within S. aureus OhyA channel oleate to the active site, curl oleate around the substrate water, and stabilize the hydroxylated product to inactivate antimicrobial fatty acids.
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Affiliation(s)
- Christopher D Radka
- The Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Justin L Batte
- The Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Matthew W Frank
- The Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Brandon M Young
- Department of Chemical Biology and Therapeutics, St Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Charles O Rock
- The Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, Tennessee, USA.
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43
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Sarkar A, Roitberg AE. pH-Dependent Conformational Changes Lead to a Highly Shifted p Ka for a Buried Glutamic Acid Mutant of SNase. J Phys Chem B 2020; 124:11072-11080. [PMID: 33259714 DOI: 10.1021/acs.jpcb.0c07136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ionizable residues are rarely present in the hydrophobic interior of proteins, but when they are, they play important roles in biological processes such as energy transduction and enzyme catalysis. Internal ionizable residues have anomalous experimental pKa values with respect to their pKa in bulk water. This work investigates the atomistic cause of the highly shifted pKa of the internal Glu23 in the artificially mutated variant V23E of Staphylococcal Nuclease (SNase) using pH replica exchange molecular dynamics (pH-REMD) simulations. The pKa of Glu23 obtained from our calculations is 6.55, which is elevated with respect to the glutamate pKa of 4.40 in bulk water. The calculated value is close to the experimental pKa of 7.10. Our simulations show that the highly shifted pKa of Glu23 is the product of a pH-dependent conformational change, which has been observed experimentally and also seen in our simulations. We carry out an analysis of this pH-dependent conformational change in response to the protonation state change of Glu23. Using a four-state thermodynamic model, we estimate the two conformation-specific pKa values of Glu23 and describe the coupling between the conformational and ionization equilibria.
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Affiliation(s)
- Ankita Sarkar
- Department of Physics, University of Florida, Gainesville, Florida 32611, United States
| | - Adrian E Roitberg
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
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44
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Cramer J, Jiang X, Schönemann W, Silbermann M, Zihlmann P, Siegrist S, Fiege B, Jakob RP, Rabbani S, Maier T, Ernst B. Enhancing the enthalpic contribution of hydrogen bonds by solvent shielding. RSC Chem Biol 2020; 1:281-287. [PMID: 34458766 PMCID: PMC8341794 DOI: 10.1039/d0cb00108b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/19/2020] [Indexed: 11/21/2022] Open
Abstract
In biological systems, polar interactions are heavily burdened by high desolvation penalties resulting from strong solute-solvent interactions. As a consequence thereof, enthalpic contributions of hydrogen bonds to the free energy of binding are severely diminished. However, this effect is strongly attenuated for interactions within solvent-shielded areas of proteins. In microcalorimetric experiments, we show that the bacterial lectin FimH utilizes conformational adaptions to effectively shield its binding site from solvent. The transition into a lower dielectric environment results in an enthalpic benefit of approximately -13 kJ mol-1 for mannoside binding. However, this effect can be abrogated, if the hydrogen bond network within the binding site is disturbed by deoxygenation of the ligand. Conformational adaption leading to reduced local dielectric constants could represent a general mechanism for proteins to enable enthalpy-driven recognition of polar ligands.
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Affiliation(s)
- Jonathan Cramer
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Xiaohua Jiang
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Wojciech Schönemann
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Marleen Silbermann
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Pascal Zihlmann
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Stefan Siegrist
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Brigitte Fiege
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Roman Peter Jakob
- Institute of Structural Biology, University of Basel Klingelbergstrasse 70 4056 Basel Switzerland
| | - Said Rabbani
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
| | - Timm Maier
- Institute of Structural Biology, University of Basel Klingelbergstrasse 70 4056 Basel Switzerland
| | - Beat Ernst
- Institute of Molecular Pharmacy, University of Basel Klingelbergstrasse 50 4056 Basel Switzerland
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45
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Fabre L, Ntreh AT, Yazidi A, Leus IV, Weeks JW, Bhattacharyya S, Ruickoldt J, Rouiller I, Zgurskaya HI, Sygusch J. A "Drug Sweeping" State of the TriABC Triclosan Efflux Pump from Pseudomonas aeruginosa. Structure 2020; 29:261-274.e6. [PMID: 32966762 DOI: 10.1016/j.str.2020.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 07/30/2020] [Accepted: 08/29/2020] [Indexed: 12/01/2022]
Abstract
The structure of the TriABC inner membrane component of the triclosan/SDS-specific efflux pump from Pseudomonas aeruginosa was determined by cryoelectron microscopy to 4.5 Å resolution. The complete structure of the inner membrane transporter TriC of the resistance-nodulation-division (RND) superfamily was solved, including a partial structure of the fused periplasmic membrane fusion subunits, TriA and TriB. The substrate-free conformation of TriABC represents an intermediate step in efflux complex assembly before the engagement of the outer membrane channel. Structural analysis identified a tunnel network whose constriction impedes substrate efflux, indicating inhibition of TriABC in the unengaged state. Blind docking studies revealed binding to TriC at the same loci by substrates and bulkier non-substrates. Together with functional analyses, we propose that selective substrate translocation involves conformational gating at the tunnel narrowing that, together with conformational ordering of TriA and TriB, creates an engaged state capable of mediating substrate efflux.
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Affiliation(s)
- Lucien Fabre
- McGill University, Department of Anatomy and Cell Biology, Montreal, QC H3A 0G4, Canada
| | - Abigail T Ntreh
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Amira Yazidi
- University of Montreal, Department of Biochemistry and Molecular Medicine, Medicine, CP 6128, Station Centre-ville, Montreal, QC H3C 3J7, Canada
| | - Inga V Leus
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Jon W Weeks
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Sudipta Bhattacharyya
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, 3010, Australia; Department of Bioscience and Bioengineering, Indian Institute of Technology Jodhpur, India
| | - Jakob Ruickoldt
- Institut für Biologie, Strukturbiologie/Biochemie, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
| | - Isabelle Rouiller
- McGill University, Department of Anatomy and Cell Biology, Montreal, QC H3A 0G4, Canada; Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Helen I Zgurskaya
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA.
| | - Jurgen Sygusch
- University of Montreal, Department of Biochemistry and Molecular Medicine, Medicine, CP 6128, Station Centre-ville, Montreal, QC H3C 3J7, Canada.
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46
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Seica AFS, Iancu CV, Pfeilschifter B, Madej MG, Choe JY, Hellwig P. Asp 22 drives the protonation state of the Staphylococcus epidermidis glucose/H + symporter. J Biol Chem 2020; 295:15253-15261. [PMID: 32859752 DOI: 10.1074/jbc.ra120.014069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/26/2020] [Indexed: 12/24/2022] Open
Abstract
The Staphylococcus epidermidis glucose/H+ symporter (GlcPSe) is a membrane transporter highly specific for glucose and a homolog of the human glucose transporters (GLUT, SLC2 family). Most GLUTs and their bacterial counterparts differ in the transport mechanism, adopting uniport and sugar/H+ symport, respectively. Unlike other bacterial GLUT homologs (for example, XylE), GlcPSe has a loose H+/sugar coupling. Asp22 is part of the proton-binding site of GlcPSe and crucial for the glucose/H+ co-transport mechanism. To determine how pH variations affect the proton site and the transporter, we performed surface-enhanced IR absorption spectroscopy on the immobilized GlcPSe We found that Asp22 has a pKa of 8.5 ± 0.1, a value consistent with that determined previously for glucose transport, confirming the central role of this residue for the transport mechanism of GlcPSe A neutral replacement of the negatively charged Asp22 led to positive charge displacements over the entire pH range, suggesting that the polarity change of the WT reflects the protonation state of Asp22 We expected that the substitution of the residue Ile105 for a serine, located within hydrogen-bonding distance to Asp22, would change the microenvironment, but the pKa of Asp22 corresponded to that of the WT. A167E mutation, selected in analogy to the XylE, introduced an additional protonatable site and perturbed the protonation state of Asp22, with the latter now exhibiting a pKa of 6.4. These studies confirm that Asp22 is the proton-binding residue in GlcPSe and show that charged residues in its vicinity affect the pKa of glucose/H+ symport.
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Affiliation(s)
- Ana Filipa Santos Seica
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, CMC, Université de Strasbourg CNRS, Strasbourg, France
| | - Cristina V Iancu
- Department of Chemistry, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA
| | - Benedikt Pfeilschifter
- University of Regensburg, Institute of Biophysics and Physical Biochemistry, Regensburg, Germany
| | - M Gregor Madej
- University of Regensburg, Institute of Biophysics and Physical Biochemistry, Regensburg, Germany
| | - Jun-Yong Choe
- Department of Chemistry, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Department of Biochemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA.
| | - Petra Hellwig
- Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, CMC, Université de Strasbourg CNRS, Strasbourg, France
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47
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Mahmood MS, Irshad S, Butt TA, Batool H, Batool S, Ashraf NM. In-silico analysis of deleterious missense SNPs of human TYR gene associated with oculocutaneous albinism type 1 (OCA1). Meta Gene 2020. [DOI: 10.1016/j.mgene.2020.100674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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48
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Sofronov O, Giubertoni G, Pérez de Alba Ortíz A, Ensing B, Bakker HJ. Peptide Side-COOH Groups Have Two Distinct Conformations under Biorelevant Conditions. J Phys Chem Lett 2020; 11:3466-3472. [PMID: 32293901 PMCID: PMC7212517 DOI: 10.1021/acs.jpclett.0c00711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
The carboxyl (COOH) side chain groups of amino acids, such as aspartic acid, play an important role in biochemical processes, including enzymatic proton transport. In many theoretical studies, it was found that the (bio)chemical reactivity of the carboxyl group strongly depends on the conformation of this group. Interestingly, up to now there has been no experimental investigation of the geometry and the stability of different COOH conformers under biorelevant conditions. Here, we investigate the conformational isomerism of the side chain COOH group of N-acetyl aspartic acid amide using polarization-resolved two-dimensional infrared spectroscopy. We find that the carboxyl group shows two distinct near-planar conformers (syn and anti) when dissolved in water at room temperature. Both conformers are significantly populated in aqueous solution (75 ± 10% and 25 ± 10% for syn and anti, respectively). Molecular dynamics simulations show that the anti conformer interacts more strongly with water molecules than the syn conformer, explaining why this conformer is significantly present in aqueous solution.
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Affiliation(s)
| | | | - Alberto Pérez de Alba Ortíz
- Amsterdam
Center for Multiscale Modeling and Van ’t Hoff Institute for
Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Bernd Ensing
- Amsterdam
Center for Multiscale Modeling and Van ’t Hoff Institute for
Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Huib J. Bakker
- AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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49
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Ma C, Malessa A, Boersma AJ, Liu K, Herrmann A. Supercharged Proteins and Polypeptides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905309. [PMID: 31943419 DOI: 10.1002/adma.201905309] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/10/2019] [Indexed: 06/10/2023]
Abstract
Electrostatic interactions play a vital role in nature. Biomacromolecules such as proteins are orchestrated by electrostatics, among other intermolecular forces, to assemble and organize biochemistry. Natural proteins with a high net charge exist in a folded state or are unstructured and can be an inspiration for scientists to artificially supercharge other protein entities. Recent findings show that supercharging proteins allows for control of their properties such as temperature resistance and catalytic activity. One elegant method to transfer the favorable properties of supercharged proteins to other proteins is the fabrication of fusions. Genetically engineered, supercharged unstructured polypeptides (SUPs) are just one promising fusion tool. SUPs can also be complexed with artificial entities to yield thermotropic and lyotropic liquid crystals and liquids. These architectures represent novel bulk materials that are sensitive to external stimuli. Interestingly, SUPs undergo fluid-fluid phase separation to form coacervates. These coacervates can even be directly generated in living cells or can be combined with dissipative fiber assemblies that induce life-like features. Supercharged proteins and SUPs are developed into exciting classes of materials. Their synthesis, structures, and properties are summarized. Moreover, potential applications are highlighted and challenges are discussed.
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Affiliation(s)
- Chao Ma
- Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Anke Malessa
- Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Arnold J Boersma
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany
| | - Kai Liu
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China
| | - Andreas Herrmann
- Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
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50
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Reyna-Fabián ME, Hernández-Martínez NL, Alcántara-Ortigoza MA, Ayala-Sumuano JT, Enríquez-Flores S, Velázquez-Aragón JA, Varela-Echavarría A, Todd-Quiñones CG, González-Del Angel A. First comprehensive TSC1/TSC2 mutational analysis in Mexican patients with Tuberous Sclerosis Complex reveals numerous novel pathogenic variants. Sci Rep 2020; 10:6589. [PMID: 32313033 PMCID: PMC7170856 DOI: 10.1038/s41598-020-62759-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/11/2020] [Indexed: 12/12/2022] Open
Abstract
The aim of this study was to improve knowledge of the mutational spectrum causing tuberous sclerosis complex (TSC) in a sample of Mexican patients, given the limited information available regarding this disease in Mexico and Latin America. Four different molecular techniques were implemented to identify from single nucleotide variants to large rearrangements in the TSC1 and TSC2 genes of 66 unrelated Mexican-descent patients that clinically fulfilled the criteria for a definitive TSC diagnosis. The mutation detection rate was 94%, TSC2 pathogenic variants (PV) prevailed over TSC1 PV (77% vs. 23%) and a recurrent mutation site (hotspot) was observed in TSC1 exon 15. Interestingly, 40% of the identified mutations had not been previously reported. The wide range of novels PV made it difficult to establish any genotype-phenotype correlation, but most of the PV conditioned neurological involvement (intellectual disability and epilepsy). Our 3D protein modeling of two variants classified as likely pathogenic demonstrated that they could alter the structure and function of the hamartin (TSC1) or tuberin (TSC2) proteins. Molecular analyses of parents and first-degree affected family members of the index cases enabled us to distinguish familial (18%) from sporadic (82%) cases and to identify one case of apparent gonadal mosaicism.
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Affiliation(s)
- Miriam E Reyna-Fabián
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México, México
| | - Nancy L Hernández-Martínez
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México, México
| | - Miguel A Alcántara-Ortigoza
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México, México
| | | | - Sergio Enríquez-Flores
- Grupo de Investigación en Biomoléculas y Salud Infantil, Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Ciudad de México, México
| | - José A Velázquez-Aragón
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México, México
| | - Alfredo Varela-Echavarría
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México
| | - Carlos G Todd-Quiñones
- Posgrado en Biología Experimental, Universidad Autónoma Metropolitana-Iztapalapa, Ciudad de México, México
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Hospital de Alta Especialidad de Veracruz, Veracruz, México
| | - Ariadna González-Del Angel
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México, México.
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