1
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Marafie SK, Alshawaf E, Abu-Farha M, Thanaraj TA, Wei DQ, Al-Mulla F, Khan A, Abubaker J, Mohammad A. Exploring the Binding Mechanism of NRG1-ERBB3 Complex and Discovery of Potent Natural Products to Reduce Diabetes-Assisted Breast Cancer Progression. Interdiscip Sci 2023:10.1007/s12539-023-00566-y. [PMID: 37389721 PMCID: PMC10374477 DOI: 10.1007/s12539-023-00566-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 03/25/2023] [Accepted: 03/30/2023] [Indexed: 07/01/2023]
Abstract
Diabetes mellitus significantly contributes to breast cancer progression, where hyperglycemia upregulates specific genes, leading to more aggressive tumor growth. In patients with BC that develop diabetes, neuregulin 1 (NRG1) and epidermal growth factor receptor 3 (ERBB3) overexpression exacerbate tumor growth and progression. Since the interaction between NRG1 and ERBB3 is critical for tumor growth, understanding the molecular mechanisms underlying NRG1-ERBB3 complex formation is essential for elucidating diabetes-assisted breast cancer progression. However, the key residues forming the NRG1-ERBB3 complex remain unknown. Here, we substituted specific residues in NRG1 with alanine and studied its interactions with ERBB3 using computational structural biology tools. We further screened the South African natural compounds database to target the complex's interface residues to discover potential inhibitors. The conformational stability and dynamic features of NRG1-WT, -H2A, -L3A, and -K35A complexed with ERBB3 were subjected to 400 ns molecular dynamics simulations. The free binding energies of all NRG1-ERBB3 complexes were calculated using the molecular mechanics-generalized Born surface area (MM/GBSA). The H2 and L3 alanine substitutions caused a loss of interaction with ERBB3 residue D73, weakening the interaction with ERBB3. Screening 1300 natural compounds identified four (SANC00643, SANC00824, SANC00975, and SANC00335) with the best potential to inhibit ERRB3-NRG1 coupling. The binding free energies for each complex were - 48.55 kcal/mol for SANC00643, - 47.68 kcal/mol for SANC00824, - 46.04 kcal/mol for SANC00975, and - 45.29 kcal/mol for SANC00335, showing their overall stronger binding with ERBB3 than NRG1 and their potential to act as ERBB3-NRG1 complex inhibitors. In conclusion, this complex may represent a residue-specific drug target to inhibit BC progression.
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Affiliation(s)
- Sulaiman K Marafie
- Department of Biochemistry and Molecular Biology, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Eman Alshawaf
- Department of Biochemistry and Molecular Biology, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Mohamed Abu-Farha
- Department of Biochemistry and Molecular Biology, Dasman Diabetes Institute, Kuwait City, Kuwait
- Special Service Facilities, Dasman Diabetes Institute, Kuwait City, Kuwait
| | | | - Dong-Qing Wei
- Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Fahd Al-Mulla
- Department of Genetics and Bioinformatics, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Abbas Khan
- Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Jehad Abubaker
- Department of Biochemistry and Molecular Biology, Dasman Diabetes Institute, Kuwait City, Kuwait.
| | - Anwar Mohammad
- Department of Biochemistry and Molecular Biology, Dasman Diabetes Institute, Kuwait City, Kuwait.
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2
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A Panel of Engineered Ubiquitin Variants Targeting the Family of Domains Found in Ubiquitin Specific Proteases (DUSPs). J Mol Biol 2021; 433:167300. [PMID: 34666042 DOI: 10.1016/j.jmb.2021.167300] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 09/16/2021] [Accepted: 10/04/2021] [Indexed: 11/21/2022]
Abstract
Domains found in ubiquitin specific proteases (DUSPs) occur in seven members of the ubiquitin specific protease (USP) family. DUSPs are defined by a distinct structural fold but their functions remain largely unknown, although studies with USP4 suggest that its DUSP enhances deubiquitination activity. We used phage-displayed libraries of ubiquitin variants (UbVs) to derive protein-based tools to target DUSP family members with high affinity and specificity. We designed a UbV library based on insights from the structure of a previously identified UbV bound to the DUSP of USP15. The new library yielded 33 unique UbVs that bound to DUSPs from five different USPs (USP4, USP11, USP15, USP20 and USP33). For each USP, we were able to identify at least one DUSP that bound with high affinity and absolute specificity relative to the other DUSPs. We showed that UbVs targeting the DUSPs of USP15, USP11 and USP20 inhibited the catalytic activity of the enzyme, despite the fact that the DUSP is located outside of the catalytic domain. These findings provide an alternative means of inhibiting USP activity by targeting DUSPs, and this mechanism could be potentially extended other DUSP-containing USPs.
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3
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Basu S, Chakravarty D, Bhattacharyya D, Saha P, Patra HK. Plausible blockers of Spike RBD in SARS-CoV2-molecular design and underlying interaction dynamics from high-level structural descriptors. J Mol Model 2021; 27:191. [PMID: 34057647 PMCID: PMC8165686 DOI: 10.1007/s00894-021-04779-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 04/26/2021] [Indexed: 12/24/2022]
Abstract
Abstract COVID-19 is characterized by an unprecedented abrupt increase in the viral transmission rate (SARS-CoV-2) relative to its pandemic evolutionary ancestor, SARS-CoV (2003). The complex molecular cascade of events related to the viral pathogenicity is triggered by the Spike protein upon interacting with the ACE2 receptor on human lung cells through its receptor binding domain (RBDSpike). One potential therapeutic strategy to combat COVID-19 could thus be limiting the infection by blocking this key interaction. In this current study, we adopt a protein design approach to predict and propose non-virulent structural mimics of the RBDSpike which can potentially serve as its competitive inhibitors in binding to ACE2. The RBDSpike is an independently foldable protein domain, resilient to conformational changes upon mutations and therefore an attractive target for strategic re-design. Interestingly, in spite of displaying an optimal shape fit between their interacting surfaces (attributed to a consequently high mutual affinity), the RBDSpike–ACE2 interaction appears to have a quasi-stable character due to a poor electrostatic match at their interface. Structural analyses of homologous protein complexes reveal that the ACE2 binding site of RBDSpike has an unusually high degree of solvent-exposed hydrophobic residues, attributed to key evolutionary changes, making it inherently “reaction-prone.” The designed mimics aimed to block the viral entry by occupying the available binding sites on ACE2, are tested to have signatures of stable high-affinity binding with ACE2 (cross-validated by appropriate free energy estimates), overriding the native quasi-stable feature. The results show the apt of directly adapting natural examples in rational protein design, wherein, homology-based threading coupled with strategic “hydrophobic ↔ polar” mutations serve as a potential breakthrough. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1007/s00894-021-04779-0.
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Affiliation(s)
- Sankar Basu
- Department of Microbiology, Asutosh College (affiliated to University of Calcutta), Kolkata, 700026, West Bengal, India.
| | - Devlina Chakravarty
- Department of Chemistry, University of Rutgers-Camden, Camden, 08102, NJ, USA
| | - Dhananjay Bhattacharyya
- Computational Science Division, Saha Institute of Nuclear Physics, Kolkata, 700064, West Bengal, India
| | - Pampa Saha
- Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Hirak K Patra
- Department of Surgical Biotechnology, Division of Surgery and Interventional Science, University College London, London, NW3 2PF, UK
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4
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Hait S, Mallik S, Basu S, Kundu S. Finding the generalized molecular principles of protein thermal stability. Proteins 2019; 88:788-808. [PMID: 31872464 DOI: 10.1002/prot.25866] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 12/05/2019] [Accepted: 12/14/2019] [Indexed: 11/09/2022]
Abstract
Are there any generalized molecular principles of thermal adaptation? Here, integrating the concepts of structural bioinformatics, sequence analysis, and classical knot theory, we develop a robust computational framework that seeks for mechanisms of thermal adaptation by comparing orthologous mesophilic-thermophilic and mesophilic-hyperthermophilic proteins of remarkable structural and topological similarities, and still leads us to context-independent results. A comprehensive analysis of 4741 high-resolution, non-redundant X-ray crystallographic structures collected from 11 hyperthermophilic, 32 thermophilic and 53 mesophilic prokaryotes unravels at least five "nearly universal" signatures of thermal adaptation, irrespective of the enormous sequence, structure, and functional diversity of the proteins compared. A careful investigation further extracts a set of amino acid changes that can potentially enhance protein thermal stability, and remarkably, these mutations are overrepresented in protein crystallization experiments, in disorder-to-order transitions and in engineered thermostable variants of existing mesophilic proteins. These results could be helpful to find a precise, global picture of thermal adaptation.
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Affiliation(s)
- Suman Hait
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, Kolkata, India
| | - Saurav Mallik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Sudipto Basu
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, Kolkata, India.,Center of Excellence in Systems Biology and Biomedical Engineering (TEQIP Phase-III), University of Calcutta, Kolkata, India
| | - Sudip Kundu
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, Kolkata, India.,Center of Excellence in Systems Biology and Biomedical Engineering (TEQIP Phase-III), University of Calcutta, Kolkata, India
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5
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Venev SV, Zeldovich KB. Thermophilic Adaptation in Prokaryotes Is Constrained by Metabolic Costs of Proteostasis. Mol Biol Evol 2019; 35:211-224. [PMID: 29106597 PMCID: PMC5850847 DOI: 10.1093/molbev/msx282] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Prokaryotes evolved to thrive in an extremely diverse set of habitats, and their proteomes bear signatures of environmental conditions. Although correlations between amino acid usage and environmental temperature are well-documented, understanding of the mechanisms of thermal adaptation remains incomplete. Here, we couple the energetic costs of protein folding and protein homeostasis to build a microscopic model explaining both the overall amino acid composition and its temperature trends. Low biosynthesis costs lead to low diversity of physical interactions between amino acid residues, which in turn makes proteins less stable and drives up chaperone activity to maintain appropriate levels of folded, functional proteins. Assuming that the cost of chaperone activity is proportional to the fraction of unfolded client proteins, we simulated thermal adaptation of model proteins subject to minimization of the total cost of amino acid synthesis and chaperone activity. For the first time, we predicted both the proteome-average amino acid abundances and their temperature trends simultaneously, and found strong correlations between model predictions and 402 genomes of bacteria and archaea. The energetic constraint on protein evolution is more apparent in highly expressed proteins, selected by codon adaptation index. We found that in bacteria, highly expressed proteins are similar in composition to thermophilic ones, whereas in archaea no correlation between predicted expression level and thermostability was observed. At the same time, thermal adaptations of highly expressed proteins in bacteria and archaea are nearly identical, suggesting that universal energetic constraints prevail over the phylogenetic differences between these domains of life.
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Affiliation(s)
- Sergey V Venev
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, 368 Plantation St, Worcester, MA
| | - Konstantin B Zeldovich
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, 368 Plantation St, Worcester, MA
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6
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Zhou HX, Pang X. Electrostatic Interactions in Protein Structure, Folding, Binding, and Condensation. Chem Rev 2018; 118:1691-1741. [PMID: 29319301 DOI: 10.1021/acs.chemrev.7b00305] [Citation(s) in RCA: 485] [Impact Index Per Article: 80.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Charged and polar groups, through forming ion pairs, hydrogen bonds, and other less specific electrostatic interactions, impart important properties to proteins. Modulation of the charges on the amino acids, e.g., by pH and by phosphorylation and dephosphorylation, have significant effects such as protein denaturation and switch-like response of signal transduction networks. This review aims to present a unifying theme among the various effects of protein charges and polar groups. Simple models will be used to illustrate basic ideas about electrostatic interactions in proteins, and these ideas in turn will be used to elucidate the roles of electrostatic interactions in protein structure, folding, binding, condensation, and related biological functions. In particular, we will examine how charged side chains are spatially distributed in various types of proteins and how electrostatic interactions affect thermodynamic and kinetic properties of proteins. Our hope is to capture both important historical developments and recent experimental and theoretical advances in quantifying electrostatic contributions of proteins.
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Affiliation(s)
- Huan-Xiang Zhou
- Department of Chemistry and Department of Physics, University of Illinois at Chicago , Chicago, Illinois 60607, United States.,Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
| | - Xiaodong Pang
- Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
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7
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Sawle L, Huihui J, Ghosh K. All-Atom Simulations Reveal Protein Charge Decoration in the Folded and Unfolded Ensemble Is Key in Thermophilic Adaptation. J Chem Theory Comput 2017; 13:5065-5075. [DOI: 10.1021/acs.jctc.7b00545] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lucas Sawle
- Department of Physics and
Astronomy, University of Denver, Denver, Colorado 80208, United States
| | - Jonathan Huihui
- Department of Physics and
Astronomy, University of Denver, Denver, Colorado 80208, United States
| | - Kingshuk Ghosh
- Department of Physics and
Astronomy, University of Denver, Denver, Colorado 80208, United States
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8
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Abstract
![]()
We review how major cell behaviors,
such as bacterial growth laws,
are derived from the physical chemistry of the cell’s proteins.
On one hand, cell actions depend on the individual biological functionalities
of their many genes and proteins. On the other hand, the common physics
among proteins can be as important as the unique biology that distinguishes
them. For example, bacterial growth rates depend strongly on temperature.
This dependence can be explained by the folding stabilities across
a cell’s proteome. Such modeling explains how thermophilic
and mesophilic organisms differ, and how oxidative damage of highly
charged proteins can lead to unfolding and aggregation in aging cells.
Cells have characteristic time scales. For example, E. coli can duplicate as fast as 2–3 times per hour. These time scales
can be explained by protein dynamics (the rates of synthesis and degradation,
folding, and diffusional transport). It rationalizes how bacterial
growth is slowed down by added salt. In the same way that the behaviors
of inanimate materials can be expressed in terms of the statistical
distributions of atoms and molecules, some cell behaviors can be expressed
in terms of distributions of protein properties, giving insights into
the microscopic basis of growth laws in simple cells.
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Affiliation(s)
- Kingshuk Ghosh
- Department of Physics and Astronomy, University of Denver , Denver, Colorado 80209, United States
| | - Adam M R de Graff
- Laufer Center for Physical and Quantitative Biology and Departments of Chemistry and Physics and Astronomy, Stony Brook University , Stony Brook, New York 11794, United States
| | - Lucas Sawle
- Department of Physics and Astronomy, University of Denver , Denver, Colorado 80209, United States
| | - Ken A Dill
- Laufer Center for Physical and Quantitative Biology and Departments of Chemistry and Physics and Astronomy, Stony Brook University , Stony Brook, New York 11794, United States
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9
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Højgaard C, Kofoed C, Espersen R, Johansson KE, Villa M, Willemoës M, Lindorff-Larsen K, Teilum K, Winther JR. A Soluble, Folded Protein without Charged Amino Acid Residues. Biochemistry 2016; 55:3949-56. [PMID: 27307139 DOI: 10.1021/acs.biochem.6b00269] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Charges are considered an integral part of protein structure and function, enhancing solubility and providing specificity in molecular interactions. We wished to investigate whether charged amino acids are indeed required for protein biogenesis and whether a protein completely free of titratable side chains can maintain solubility, stability, and function. As a model, we used a cellulose-binding domain from Cellulomonas fimi, which, among proteins of more than 100 amino acids, presently is the least charged in the Protein Data Bank, with a total of only four titratable residues. We find that the protein shows a surprising resilience toward extremes of pH, demonstrating stability and function (cellulose binding) in the pH range from 2 to 11. To ask whether the four charged residues present were required for these properties of this protein, we altered them to nontitratable ones. Remarkably, this chargeless protein is produced reasonably well in Escherichia coli, retains its stable three-dimensional structure, and is still capable of strong cellulose binding. To further deprive this protein of charges, we removed the N-terminal charge by acetylation and studied the protein at pH 2, where the C-terminus is effectively protonated. Under these conditions, the protein retains its function and proved to be both soluble and have a reversible folding-unfolding transition. To the best of our knowledge, this is the first time a soluble, functional protein with no titratable side chains has been produced.
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Affiliation(s)
- Casper Højgaard
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Christian Kofoed
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Roall Espersen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Kristoffer Enøe Johansson
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Mara Villa
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Martin Willemoës
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Kresten Lindorff-Larsen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Kaare Teilum
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
| | - Jakob R Winther
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , DK-2200 Copenhagen N, Denmark
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10
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Modulation of folding energy landscape by charge-charge interactions: linking experiments with computational modeling. Proc Natl Acad Sci U S A 2015; 112:E259-66. [PMID: 25564663 DOI: 10.1073/pnas.1410424112] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The kinetics of folding-unfolding of a structurally diverse set of four proteins optimized for thermodynamic stability by rational redesign of surface charge-charge interactions is characterized experimentally. The folding rates are faster for designed variants compared with their wild-type proteins, whereas the unfolding rates are largely unaffected. A simple structure-based computational model, which incorporates the Debye-Hückel formalism for the electrostatics, was used and found to qualitatively recapitulate the experimental results. Analysis of the energy landscapes of the designed versus wild-type proteins indicates the differences in refolding rates may be correlated with the degree of frustration of their respective energy landscapes. Our simulations indicate that naturally occurring wild-type proteins have frustrated folding landscapes due to the surface electrostatics. Optimization of the surface electrostatics seems to remove some of that frustration, leading to enhanced formation of native-like contacts in the transition-state ensembles (TSE) and providing a less frustrated energy landscape between the unfolded and TS ensembles. Macroscopically, this results in faster folding rates. Furthermore, analyses of pairwise distances and radii of gyration suggest that the less frustrated energy landscapes for optimized variants are a result of more compact unfolded and TS ensembles. These findings from our modeling demonstrates that this simple model may be used to: (i) gain a detailed understanding of charge-charge interactions and their effects on modulating the energy landscape of protein folding and (ii) qualitatively predict the kinetic behavior of protein surface electrostatic interactions.
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11
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Der BS, Kluwe C, Miklos AE, Jacak R, Lyskov S, Gray JJ, Georgiou G, Ellington AD, Kuhlman B. Alternative computational protocols for supercharging protein surfaces for reversible unfolding and retention of stability. PLoS One 2013; 8:e64363. [PMID: 23741319 PMCID: PMC3669367 DOI: 10.1371/journal.pone.0064363] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 04/11/2013] [Indexed: 12/29/2022] Open
Abstract
Reengineering protein surfaces to exhibit high net charge, referred to as “supercharging”, can improve reversibility of unfolding by preventing aggregation of partially unfolded states. Incorporation of charged side chains should be optimized while considering structural and energetic consequences, as numerous mutations and accumulation of like-charges can also destabilize the native state. A previously demonstrated approach deterministically mutates flexible polar residues (amino acids DERKNQ) with the fewest average neighboring atoms per side chain atom (AvNAPSA). Our approach uses Rosetta-based energy calculations to choose the surface mutations. Both protocols are available for use through the ROSIE web server. The automated Rosetta and AvNAPSA approaches for supercharging choose dissimilar mutations, raising an interesting division in surface charging strategy. Rosetta-supercharged variants of GFP (RscG) ranging from −11 to −61 and +7 to +58 were experimentally tested, and for comparison, we re-tested the previously developed AvNAPSA-supercharged variants of GFP (AscG) with +36 and −30 net charge. Mid-charge variants demonstrated ∼3-fold improvement in refolding with retention of stability. However, as we pushed to higher net charges, expression and soluble yield decreased, indicating that net charge or mutational load may be limiting factors. Interestingly, the two different approaches resulted in GFP variants with similar refolding properties. Our results show that there are multiple sets of residues that can be mutated to successfully supercharge a protein, and combining alternative supercharge protocols with experimental testing can be an effective approach for charge-based improvement to refolding.
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Affiliation(s)
- Bryan S. Der
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Christien Kluwe
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas, United States of America
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, United States of America
| | - Aleksandr E. Miklos
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas, United States of America
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, United States of America
- Applied Research Laboratories, University of Texas at Austin, Austin, Texas, United States of America
| | - Ron Jacak
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sergey Lyskov
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jeffrey J. Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - George Georgiou
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, United States of America
| | - Andrew D. Ellington
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas, United States of America
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, United States of America
- Applied Research Laboratories, University of Texas at Austin, Austin, Texas, United States of America
| | - Brian Kuhlman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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12
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Abstract
Surface charges of proteins have in several cases been found to function as "structural gatekeepers," which avoid unwanted interactions by negative design, for example, in the control of protein aggregation and binding. The question is then if side-chain charges, due to their desolvation penalties, play a corresponding role in protein folding by avoiding competing, misfolded traps? To find out, we removed all 32 side-chain charges from the 101-residue protein S6 from Thermus thermophilus. The results show that the charge-depleted S6 variant not only retains its native structure and cooperative folding transition, but folds also faster than the wild-type protein. In addition, charge removal unleashes pronounced aggregation on longer timescales. S6 provides thus an example where the bias toward native contacts of a naturally evolved protein sequence is independent of charges, and point at a fundamental difference in the codes for folding and intermolecular interaction: specificity in folding is governed primarily by hydrophobic packing and hydrogen bonding, whereas solubility and binding relies critically on the interplay of side-chain charges.
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13
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Shaw BF, Schneider GF, Arthanari H, Narovlyansky M, Moustakas D, Durazo A, Wagner G, Whitesides GM. Complexes of native ubiquitin and dodecyl sulfate illustrate the nature of hydrophobic and electrostatic interactions in the binding of proteins and surfactants. J Am Chem Soc 2011; 133:17681-95. [PMID: 21939262 DOI: 10.1021/ja205735q] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A previous study, using capillary electrophoresis (CE) [J. Am. Chem. Soc. 2008, 130, 17384-17393], reported that six discrete complexes of ubiquitin (UBI) and sodium dodecyl sulfate (SDS) form at different concentrations of SDS along the pathway to unfolding of UBI in solutions of SDS. One complex (which formed between 0.8 and 1.8 mM SDS) consisted of native UBI associated with approximately 11 molecules of SDS. The current study used CE and (15)N/(13)C-(1)H heteronuclear single quantum coherence (HSQC) NMR spectroscopy to identify residues in folded UBI that associate specifically with SDS at 0.8-1.8 mM SDS, and to correlate these associations with established biophysical and structural properties of this well-characterized protein. The ability of the surface charge and hydrophobicity of folded UBI to affect the association with SDS (at concentrations below the CMC) was studied, using CE, by converting lys-ε-NH(3)(+) to lys-ε-NHCOCH(3) groups. According to CE, the acetylation of lysine residues inhibited the binding of 11 SDS ([SDS] < 2 mM) and decreased the number of complexes of composition UBI-(NHAc)(8)·SDS(n) that formed on the pathway of unfolding of UBI-(NHAc)(8) in SDS. A comparison of (15)N-(1)H HSQC spectra at 0 mM and 1 mM SDS with calculated electrostatic surface potentials of folded UBI (e.g., solutions to the nonlinear Poisson-Boltzmann (PB) equation) suggested, however, that SDS binds preferentially to native UBI at hydrophobic residues that are formally neutral (i.e., Leu and Ile), but that have positive electrostatic surface potential (as predicted from solutions to nonlinear PB equations); SDS did not uniformly interact with residues that have formal positive charge (e.g., Lys or Arg). Cationic functional groups, therefore, promote the binding of SDS to folded UBI because these groups exert long-range effects on the positive electrostatic surface potential (which extend beyond their own van der Waals radii, as predicted from PB theory), and not because cationic groups are necessarily the site of ionic interactions with sulfate groups. Moreover, SDS associated with residues in native UBI without regard to their location in α-helix or β-sheet structure (although residues in hydrogen-bonded loops did not bind SDS). No correlation was observed between the association of an amino acid with SDS and the solvent accessibility of the residue or its rate of amide H/D exchange. This study establishes a few (of perhaps several) factors that control the simultaneous molecular recognition of multiple anionic amphiphiles by a folded cytosolic protein.
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Affiliation(s)
- Bryan F Shaw
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.
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14
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Schneider GF, Shaw BF, Lee A, Carillho E, Whitesides GM. Pathway for unfolding of ubiquitin in sodium dodecyl sulfate, studied by capillary electrophoresis. J Am Chem Soc 2009; 130:17384-93. [PMID: 19035631 DOI: 10.1021/ja804736t] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
This paper characterizes the complexes formed by a small protein, ubiquitin (UBI), and a negatively charged surfactant, sodium dodecyl sulfate (SDS), using capillary electrophoresis (CE), circular dichroism (CD), and amide hydrogen-deuterium exchange (HDX; as monitored by mass spectroscopy, MS). Capillary electrophoresis of complexes of UBI and SDS, at apparent equilibrium, at concentrations of SDS ranging from sub-micellar and sub-denaturing to micellar and denaturing, revealed multiple complexes of UBI and SDS of the general composition UBI-SDS(n). Examination of electrophoretic mobilities of complexes of UBI and SDS as a function of the concentration of SDS provided a new way to characterize the interaction of this protein with SDS and established key characteristics of this system: e.g., the reversibility of the formation of the complexes, their approximate chemical compositions, and the pathway of SDS binding to UBI. The work identified, in addition to SDS-saturated UBI, at least six groups of complexes of UBI with SDS, within which four groups were populated with complexes of distinct stoichiometries: UBI-SDS(approximately 11), UBI-SDS(approximately 25), UBI-SDS(approximately 33), and UBI-SDS(approximately 42). CD spectroscopy and amide HDX of the UBI-SDS(n) complexes suggested that many of the UBI-SDS(n) complexes (n > 11) have greater alpha-helical content than native UBI. Capillary electrophoresis provides a level of detail about interactions of proteins and SDS that has not previously been accessible, and CE is an analytical and biophysical method for studies of interactions of proteins and surfactants that is both convenient and practical. This study sheds light on the formation of the enigmatic protein-SDS complexes formed during SDS polyacrylamide gel electrophoresis and brings a new tool to the study of proteins and detergents.
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Affiliation(s)
- Grégory F Schneider
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA
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Rational stabilization of enzymes by computational redesign of surface charge-charge interactions. Proc Natl Acad Sci U S A 2009; 106:2601-6. [PMID: 19196981 DOI: 10.1073/pnas.0808220106] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Here, we report the application of a computational approach that allows the rational design of enzymes with enhanced thermostability while retaining full enzymatic activity. The approach is based on the optimization of the energy of charge-charge interactions on the protein surface. We experimentally tested the validity of the approach on 2 human enzymes, acylphosphatase (AcPh) and Cdc42 GTPase, that differ in size (98 vs. 198-aa residues, respectively) and tertiary structure. We show that the designed proteins are significantly more stable than the corresponding WT proteins. The increase in stability is not accompanied by significant changes in structure, oligomerization state, or, most importantly, activity of the designed AcPh or Cdc42. This success of the design methodology suggests that it can be universally applied to other enzymes, on its own or in combination with the other strategies based on redesign of the interactions in the protein core.
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Lindman S, Xue WF, Szczepankiewicz O, Bauer MC, Nilsson H, Linse S. Salting the charged surface: pH and salt dependence of protein G B1 stability. Biophys J 2006; 90:2911-21. [PMID: 16443658 PMCID: PMC1414578 DOI: 10.1529/biophysj.105.071050] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This study shows significant effects of protein surface charges on stability and these effects are not eliminated by salt screening. The stability for a variant of protein G B1 domain was studied in the pH-range of 1.5-11 at low, 0.15 M, and 2 M salt. The variant has three mutations, T2Q, N8D, and N37D, to guarantee an intact covalent chain at all pH values. The stability of the protein shows distinct pH dependence with the highest stability close to the isoelectric point. The stability is pH-dependent at all three NaCl concentrations, indicating that interactions involving charged residues are important at all three conditions. We find that 2 M salt stabilizes the protein at low pH (protein net charge is +6 and total number of charges is 6) but not at high pH (net charge is <or=-6 and total number of charges is >or=18). Furthermore, 0.15 M salt slightly decreases the stability of the protein over the pH range. The results show that a net charge of the protein is destabilizing and indicate that proteins contain charges for reasons other than improved stability. Salt seems to reduce the electrostatic contributions to stability under conditions with few total charges, but cannot eliminate electrostatic effects in highly charged systems.
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Affiliation(s)
- Stina Lindman
- Department of Biophysical Chemistry, Lund University, Lund, Sweden
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Dell'Orco D, Xue WF, Thulin E, Linse S. Electrostatic contributions to the kinetics and thermodynamics of protein assembly. Biophys J 2004; 88:1991-2002. [PMID: 15596501 PMCID: PMC1305251 DOI: 10.1529/biophysj.104.049189] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The role of electrostatic interactions in the assembly of a native protein structure was studied using fragment complementation. Contributions of salt, pH, or surface charges to the kinetics and equilibrium of calbindin D(9k) reconstitution was measured in the presence of Ca(2+) using surface plasmon resonance and isothermal titration calorimetry. Whereas surface charge substitutions primarily affect the dissociation rate constant, the association rates are correlated with subdomain net charge in a way expected for Coulomb interactions. The affinity is reduced in all mutants, with the largest effect (260-fold) observed for the double mutant K25E+K29E. At low net charge, detailed charge distribution is important, and charges remote from the partner EF-hand have less influence than close ones. The effects of salt and pH on the reconstitution are smaller than mutational effects. The interaction between the wild-type EF-hands occurs with high affinity (K(A) = 1.3 x 10(10) M(-1); K(D) = 80 pM). The enthalpy of association is overall favorable and there appears to be a very large favorable entropic contribution from the desolvation of hydrophobic surfaces that become buried in the complex. Electrostatic interactions contribute significantly to the affinity between the subdomains, but other factors, such as hydrophobic interactions, dominate.
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Affiliation(s)
- Daniele Dell'Orco
- Department of Biophysical Chemistry, Lund University, S-221 00 Lund, Sweden
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Torrez M, Schultehenrich M, Livesay DR. Conferring thermostability to mesophilic proteins through optimized electrostatic surfaces. Biophys J 2004; 85:2845-53. [PMID: 14581189 PMCID: PMC1303565 DOI: 10.1016/s0006-3495(03)74707-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Recently, there have been several experimental reports of proteins displaying appreciable stability gains through mutation of one or two amino acid residues. Here, we employ a simple theoretical model to quickly screen mutant structures for increased thermostability through optimization of the protein's electrostatic surface. Our results are able to reproduce the experimental observation that elimination of like-charge repulsions and creation of opposite-charge attractions on the protein surface is an efficient method to confer thermostability to a mesophilic protein. Using Poisson-Boltzmann electrostatics, we calculate relative protein stabilities for the exhaustive surface mutagenesis of the cold shock, RNase T1, and CheY proteins. Comparison with 25 experimentally characterized cold shock protein mutants reveals an average correlation of 0.86. The model is also quantitatively accurate when reproducing the experimental D49A and D49H mutant stabilities of RNase T1. This work represents the first comprehensive in silico screening of mutant candidates likely to confer thermostability to mesophilic proteins through optimization of surface electrostatics. Systematic single mutant, followed by double mutant, screening yields a limited number of mutant structures displaying significant stability gains suitable for subsequent experimental characterization.
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Affiliation(s)
- Michael Torrez
- Department of Chemistry, California State Polytechnic University, Pomona, California 91767, USA
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Dong F, Zhou HX. Electrostatic contributions to T4 lysozyme stability: solvent-exposed charges versus semi-buried salt bridges. Biophys J 2002; 83:1341-7. [PMID: 12202359 PMCID: PMC1302232 DOI: 10.1016/s0006-3495(02)73904-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We carried our Poisson-Boltzmann (PB) calculations for the effects of charge reversal at five exposed sites (K16E, R119E, K135E, K147E, and R154E) and charge neutralization and proton titration of the H31-D70 semi-buried salt bridge on the stability of T4 lysozyme. Instead of the widely used solvent-exclusion (SE) surface, we used the van der Waals (vdW) surface as the boundary between the protein and solvent dielectrics (a protocol established in our earlier study on charge mutations in barnase). By including residual charge-charge interactions in the unfolded state, the five charge reversal mutations were found to have DeltaDeltaG(unfold) from -1.6 to 1.3 kcal/mol. This indicates that the variable effects of charge reversal observed by Matthews and co-workers are not unexpected. The H31N, D70N, and H31N/D70N mutations were found to destabilize the protein by 2.9, 1.3, and 1.6 kcal/mol, and the pK(a) values of H31 and D70 were shifted to 9.4 and 0.6, respectively. These results are in good accord with experimental data of Dahlquist and co-workers. In contrast, if the SE surface were used, the H31N/D70N mutant would be more stable than the wild-type protein by 1.3 kcal/mol. From these and additional results for 27 charge mutations on five other proteins, we conclude that 1) the popular view that electrostatic interactions are generally destabilizing may have been based on overestimated desolvation cost as a result of using the SE surface as the dielectric boundary; and 2) while solvent-exposed charges may not reliably contribute to protein stability, semi-buried salt bridges can provide significant stabilization.
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Affiliation(s)
- Feng Dong
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
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