1
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Oliveira RJD. Coordinate-Dependent Drift-Diffusion Reveals the Kinetic Intermediate Traps of Top7-Based Proteins. J Phys Chem B 2022; 126:10854-10869. [PMID: 36519977 DOI: 10.1021/acs.jpcb.2c07031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The computer-designed Top7 served as a scaffold to produce immunoreactive proteins by grafting of the 2F5 HIV-1 antibody epitope (Top7-2F5) followed by biotinylation (Top7-2F5-biotin). The resulting nonimmunoglobulin affinity proteins were effective in inducing and detecting the HIV-1 antibody. However, the grafted Top7-2F5 design led to protein aggregation, as opposed to the soluble biotinylated Top7-2F5-biotin. The structure-based model predicted that the thermodynamic cooperativity of Top7 increases after grafting and biotin-labeling, reducing their intermediate state populations. In this work, the folding kinetic traps that might contribute to the aggregation propensity are investigated by the diffusion theory. Since the engineered proteins have similar sequence and structural homology, they served as protein models to study the kinetic intermediate traps that were uncovered by characterizing the position-dependent drift-velocity (v(Q)) and the diffusion (D(Q)) coefficients. These coordinate-dependent coefficients were taken into account to obtain the folding and transition path times over the free energy transition states containing the intermediate kinetic traps. This analysis may be useful to predict the aggregated kinetic traps of scaffold-epitope proteins that might compose novel diagnostic and therapeutic platforms.
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Affiliation(s)
- Ronaldo Junio de Oliveira
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG38064-200, Brazil
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2
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Freitas FC, Maldonado M, Oliveira Junior AB, Onuchic JN, Oliveira RJD. Biotin-painted proteins have thermodynamic stability switched by kinetic folding routes. J Chem Phys 2022; 156:195101. [PMID: 35597640 DOI: 10.1063/5.0083875] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Biotin-labeled proteins are widely used as tools to study protein-protein interactions and proximity in living cells. Proteomic methods broadly employ proximity-labeling technologies based on protein biotinylation in order to investigate the transient encounters of biomolecules in subcellular compartments. Biotinylation is a post-translation modification in which the biotin molecule is attached to lysine or tyrosine residues. So far, biotin-based technologies proved to be effective instruments as affinity and proximity tags. However, the influence of biotinylation on aspects such as folding, binding, mobility, thermodynamic stability, and kinetics needs to be investigated. Here, we selected two proteins [biotin carboxyl carrier protein (BCCP) and FKBP3] to test the influence of biotinylation on thermodynamic and kinetic properties. Apo (without biotin) and holo (biotinylated) protein structures were used separately to generate all-atom structure-based model simulations in a wide range of temperatures. Holo BCCP contains one biotinylation site, and FKBP3 was modeled with up to 23 biotinylated lysines. The two proteins had their estimated thermodynamic stability changed by altering their energy landscape. In all cases, after comparison between the apo and holo simulations, differences were observed on the free-energy profiles and folding routes. Energetic barriers were altered with the density of states clearly showing changes in the transition state. This study suggests that analysis of large-scale datasets of biotinylation-based proximity experiments might consider possible alterations in thermostability and folding mechanisms imposed by the attached biotins.
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Affiliation(s)
- Frederico Campos Freitas
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG 38064-200, Brazil
| | - Michelli Maldonado
- Departamento de Matemática, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG 38064-200, Brazil
| | - Antonio Bento Oliveira Junior
- Center for Theoretical Biological Physics, Rice University, BioScience Research Collaborative, 6566 Main St., Houston, Texas 77030, USA
| | - José Nelson Onuchic
- Center for Theoretical Biological Physics, Rice University, BioScience Research Collaborative, 6566 Main St., Houston, Texas 77030, USA
| | - Ronaldo Junio de Oliveira
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG 38064-200, Brazil
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3
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Freitas FC, Ferreira PHB, Favaro DC, Oliveira RJD. Shedding Light on the Inhibitory Mechanisms of SARS-CoV-1/CoV-2 Spike Proteins by ACE2-Designed Peptides. J Chem Inf Model 2021; 61:1226-1243. [PMID: 33619962 PMCID: PMC7931628 DOI: 10.1021/acs.jcim.0c01320] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Indexed: 01/07/2023]
Abstract
Angiotensin-converting enzyme 2 (ACE2) is the host cellular receptor that locks onto the surface spike protein of the 2002 SARS coronavirus (SARS-CoV-1) and of the novel, highly transmissible and deadly 2019 SARS-CoV-2, responsible for the COVID-19 pandemic. One strategy to avoid the virus infection is to design peptides by extracting the human ACE2 peptidase domain α1-helix, which would bind to the coronavirus surface protein, preventing the virus entry into the host cells. The natural α1-helix peptide has a stronger affinity to SARS-CoV-2 than to SARS-CoV-1. Another peptide was designed by joining α1 with the second portion of ACE2 that is far in the peptidase sequence yet grafted in the spike protein interface with ACE2. Previous studies have shown that, among several α1-based peptides, the hybrid peptidic scaffold is the one with the highest/strongest affinity for SARS-CoV-1, which is comparable to the full-length ACE2 affinity. In this work, binding and folding dynamics of the natural and designed ACE2-based peptides were simulated by the well-known coarse-grained structure-based model, with the computed thermodynamic quantities correlating with the experimental binding affinity data. Furthermore, theoretical kinetic analysis of native contact formation revealed the distinction between these processes in the presence of the different binding partners SARS-CoV-1 and SARS-CoV-2 spike domains. Additionally, our results indicate the existence of a two-state folding mechanism for the designed peptide en route to bind to the spike proteins, in contrast to a downhill mechanism for the natural α1-helix peptides. The presented low-cost simulation protocol demonstrated its efficiency in evaluating binding affinities and identifying the mechanisms involved in the neutralization of spike-ACE2 interaction by designed peptides. Finally, the protocol can be used as a computer-based screening of more potent designed peptides by experimentalists searching for new therapeutics against COVID-19.
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Affiliation(s)
- Frederico Campos Freitas
- Laboratório de Biofísica Teórica,
Departamento de Física, Instituto de Ciências Exatas, Naturais
e Educação, Universidade Federal do Triângulo
Mineiro, Uberaba, MG 38064-200, Brazil
| | - Paulo Henrique Borges Ferreira
- Laboratório de Biofísica Teórica,
Departamento de Física, Instituto de Ciências Exatas, Naturais
e Educação, Universidade Federal do Triângulo
Mineiro, Uberaba, MG 38064-200, Brazil
| | - Denize Cristina Favaro
- Departamento de Química Orgânica,
Instituto de Química, Universidade Estadual de
Campinas, São Paulo, SP 13083-970, Brazil
| | - Ronaldo Junio de Oliveira
- Laboratório de Biofísica Teórica,
Departamento de Física, Instituto de Ciências Exatas, Naturais
e Educação, Universidade Federal do Triângulo
Mineiro, Uberaba, MG 38064-200, Brazil
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4
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Aditham AK, Markin CJ, Mokhtari DA, DelRosso N, Fordyce PM. High-Throughput Affinity Measurements of Transcription Factor and DNA Mutations Reveal Affinity and Specificity Determinants. Cell Syst 2020; 12:112-127.e11. [PMID: 33340452 DOI: 10.1016/j.cels.2020.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/08/2020] [Accepted: 11/24/2020] [Indexed: 01/28/2023]
Abstract
Transcription factors (TFs) bind regulatory DNA to control gene expression, and mutations to either TFs or DNA can alter binding affinities to rewire regulatory networks and drive phenotypic variation. While studies have profiled energetic effects of DNA mutations extensively, we lack similar information for TF variants. Here, we present STAMMP (simultaneous transcription factor affinity measurements via microfluidic protein arrays), a high-throughput microfluidic platform enabling quantitative characterization of hundreds of TF variants simultaneously. Measured affinities for ∼210 mutants of a model yeast TF (Pho4) interacting with 9 oligonucleotides (>1,800 Kds) reveal that many combinations of mutations to poorly conserved TF residues and nucleotides flanking the core binding site alter but preserve physiological binding, providing a mechanism by which combinations of mutations in cis and trans could modulate TF binding to tune occupancies during evolution. Moreover, biochemical double-mutant cycles across the TF-DNA interface reveal molecular mechanisms driving recognition, linking sequence to function. A record of this paper's Transparent Peer Review process is included in the Supplemental Information.
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Affiliation(s)
- Arjun K Aditham
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA
| | - Craig J Markin
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Daniel A Mokhtari
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Nicole DelRosso
- Graduate Program in Biophysics, Stanford University, Stanford, CA 94305, USA
| | - Polly M Fordyce
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94110, USA.
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5
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Kulandaisamy A, Srivastava A, Nagarajan R, Gromiha MM. Dissecting and analyzing key residues in protein-DNA complexes. J Mol Recognit 2017; 31. [DOI: 10.1002/jmr.2692] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/06/2017] [Accepted: 11/06/2017] [Indexed: 02/03/2023]
Affiliation(s)
- A. Kulandaisamy
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BioSciences; Indian Institute of Technology Madras; Chennai 600 036 Tamilnadu India
| | - Ambuj Srivastava
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BioSciences; Indian Institute of Technology Madras; Chennai 600 036 Tamilnadu India
| | - R. Nagarajan
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BioSciences; Indian Institute of Technology Madras; Chennai 600 036 Tamilnadu India
| | - M. Michael Gromiha
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BioSciences; Indian Institute of Technology Madras; Chennai 600 036 Tamilnadu India
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6
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Choudhury S, Ghosh B, Singh P, Ghosh R, Roy S, Pal SK. Ultrafast differential flexibility of Cro-protein binding domains of two operator DNAs with different sequences. Phys Chem Chem Phys 2016; 18:17983-90. [DOI: 10.1039/c6cp02522f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The crucial ultrafast domain fluctuation of the operator DNA OR3 over OR2 upon complexation with the repressor Cro-protein dimer has been investigated.
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Affiliation(s)
- Susobhan Choudhury
- Department of Chemical
- Biological & Macromolecular Sciences
- S. N. Bose National Centre for Basic Sciences
- Kolkata 700 098
- India
| | - Basusree Ghosh
- Division of Structural Biology and Bioinformatics
- Indian Institute of Chemical Biology
- Kolkata 700 032
- India
| | - Priya Singh
- Department of Chemical
- Biological & Macromolecular Sciences
- S. N. Bose National Centre for Basic Sciences
- Kolkata 700 098
- India
| | - Raka Ghosh
- Division of Structural Biology and Bioinformatics
- Indian Institute of Chemical Biology
- Kolkata 700 032
- India
| | - Siddhartha Roy
- Division of Structural Biology and Bioinformatics
- Indian Institute of Chemical Biology
- Kolkata 700 032
- India
| | - Samir Kumar Pal
- Department of Chemical
- Biological & Macromolecular Sciences
- S. N. Bose National Centre for Basic Sciences
- Kolkata 700 098
- India
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7
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Abstract
Biomolecules are the prime information processing elements of living matter. Most of these inanimate systems are polymers that compute their own structures and dynamics using as input seemingly random character strings of their sequence, following which they coalesce and perform integrated cellular functions. In large computational systems with finite interaction-codes, the appearance of conflicting goals is inevitable. Simple conflicting forces can lead to quite complex structures and behaviors, leading to the concept of frustration in condensed matter. We present here some basic ideas about frustration in biomolecules and how the frustration concept leads to a better appreciation of many aspects of the architecture of biomolecules, and especially how biomolecular structure connects to function by means of localized frustration. These ideas are simultaneously both seductively simple and perilously subtle to grasp completely. The energy landscape theory of protein folding provides a framework for quantifying frustration in large systems and has been implemented at many levels of description. We first review the notion of frustration from the areas of abstract logic and its uses in simple condensed matter systems. We discuss then how the frustration concept applies specifically to heteropolymers, testing folding landscape theory in computer simulations of protein models and in experimentally accessible systems. Studying the aspects of frustration averaged over many proteins provides ways to infer energy functions useful for reliable structure prediction. We discuss how frustration affects folding mechanisms. We review here how the biological functions of proteins are related to subtle local physical frustration effects and how frustration influences the appearance of metastable states, the nature of binding processes, catalysis and allosteric transitions. In this review, we also emphasize that frustration, far from being always a bad thing, is an essential feature of biomolecules that allows dynamics to be harnessed for function. In this way, we hope to illustrate how Frustration is a fundamental concept in molecular biology.
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8
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van der Vaart A. Coupled binding-bending-folding: The complex conformational dynamics of protein-DNA binding studied by atomistic molecular dynamics simulations. Biochim Biophys Acta Gen Subj 2014; 1850:1091-1098. [PMID: 25161164 DOI: 10.1016/j.bbagen.2014.08.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 08/14/2014] [Accepted: 08/18/2014] [Indexed: 12/21/2022]
Abstract
BACKGROUND Protein-DNA binding often involves dramatic conformational changes such as protein folding and DNA bending. While thermodynamic aspects of this behavior are understood, and its biological function is often known, the mechanism by which the conformational changes occur is generally unclear. By providing detailed structural and energetic data, molecular dynamics simulations have been helpful in elucidating and rationalizing protein-DNA binding. SCOPE OF REVIEW This review will summarize recent atomistic molecular dynamics simulations of the conformational dynamics of DNA and protein-DNA binding. A brief overview of recent developments in DNA force fields is given as well. MAJOR CONCLUSIONS Simulations have been crucial in rationalizing the intrinsic flexibility of DNA, and have been instrumental in identifying the sequence of binding events, the triggers for the conformational motion, and the mechanism of binding for a number of important DNA-binding proteins. GENERAL SIGNIFICANCE Molecular dynamics simulations are an important tool for understanding the complex binding behavior of DNA-binding proteins. With recent advances in force fields and rapid increases in simulation time scales, simulations will become even more important for future studies. This article is part of a Special Issue entitled Recent developments of molecular dynamics.
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Affiliation(s)
- Arjan van der Vaart
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue CHE 205, Tampa, FL 33620, USA.
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9
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Direct observation of a transient ternary complex during IκBα-mediated dissociation of NF-κB from DNA. Proc Natl Acad Sci U S A 2013; 111:225-30. [PMID: 24367071 DOI: 10.1073/pnas.1318115111] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We previously demonstrated that IκBα markedly increases the dissociation rate of DNA from NF-κB. The mechanism of this process remained a puzzle because no ternary complex was observed, and structures show that the DNA and IκBα binding sites on NF-κB are overlapping. The kinetics of interaction of IκBα with NF-κB and its complex with DNA were analyzed by using stopped-flow experiments in which fluorescence changes in pyrene-labeled DNA or the native tryptophan in IκBα were monitored. Rate constants governing the individual steps in the reaction were obtained from analysis of the measured rate vs. concentration profiles. The NF-κB association with DNA is extremely rapid with a rate constant of 1.5 × 10(8) M(-1)⋅s(-1). The NF-κB-DNA complex dissociates with a rate constant of 0.41 s(-1), yielding a KD of 2.8 nM. When IκBα is added to the NF-κB-DNA complex, we observe the formation of a transient ternary complex in the first few milliseconds of the fluorescence trace, which rapidly rearranges to release DNA. The rate constant of this IκBα-mediated dissociation is nearly equal to the rate constant of association of IκBα with the NF-κB-DNA complex, showing that IκBα is optimized to repress transcription. The rate constants for the individual steps of a more folded mutant IκBα were also measured. This mutant associates with NF-κB more rapidly than wild-type IκBα, but it associates with the NF-κB-DNA complex more slowly and also is less efficient at mediating dissociation of the NF-κB-DNA complex.
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10
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Qin Y, Yang Y, Zhang L, Fowler JD, Qiu W, Wang L, Suo Z, Zhong D. Direct probing of solvent accessibility and mobility at the binding interface of polymerase (Dpo4)-DNA complex. J Phys Chem A 2013; 117:13926-34. [PMID: 24308461 DOI: 10.1021/jp410051w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Water plays essential structural and dynamical roles in protein-DNA recognition through contributing to enthalpic or entropic stabilization of binding complex and by mediating intermolecular interactions and fluctuations for biological function. These interfacial water molecules are confined by the binding partners in nanospace, but in many cases they are highly mobile and exchange with outside bulk solution. Here, we report our studies of the interfacial water dynamics in the binary and ternary complexes of a polymerase (Dpo4) with DNA and an incoming nucleotide using a site-specific tryptophan probe with femtosecond resolution. By systematic comparison of the interfacial water motions and local side chain fluctuations in the apo, binary, and ternary states of Dpo4, we observed that the DNA binding interface and active site are dynamically solvent accessible and the interfacial water dynamics are similar to the surface hydration water fluctuations on picosecond time scales. Our molecular dynamics simulations also show the binding interface full of water molecules and nonspecific weak interactions. Such a fluid binding interface facilitates the polymerase sliding on DNA for fast translocation whereas the spacious and mobile hydrated active site contributes to the low fidelity of the lesion-bypass Y-family DNA polymerase.
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Affiliation(s)
- Yangzhong Qin
- Department of Physics, Department of Chemistry and Biochemistry, Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
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11
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Structure of the transition state for the binding of c-Myb and KIX highlights an unexpected order for a disordered system. Proc Natl Acad Sci U S A 2013; 110:14942-7. [PMID: 23980173 DOI: 10.1073/pnas.1307337110] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A classical dogma of molecular biology dictates that the 3D structure of a protein is necessary for its function. However, a considerable fraction of the human proteome, although functional, does not adopt a defined folded state under physiological conditions. These intrinsically disordered proteins tend to fold upon binding to their partners with a molecular mechanism that is elusive to experimental characterization. Indeed, although many hypotheses have been put forward, the functional role (if any) of disorder in these intrinsically denatured systems is still shrouded in mystery. Here, we characterize the structure of the transition state of the binding-induced folding in the reaction between the KIX domain of the CREB-binding protein and the transactivation domain of c-Myb. The analysis, based on the characterization of a series of conservative site-directed mutants, reveals a very high content of native-like structure in the transition state and indicates that the recognition between KIX and c-Myb is geometrically precise. The implications of our results in the light of previous work on intrinsically unstructured systems are discussed.
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12
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Spiriti J, van der Vaart A. DNA Binding and Bending by Sac7d is Stepwise. Chembiochem 2013; 14:1434-7. [DOI: 10.1002/cbic.201300264] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Indexed: 11/10/2022]
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13
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Lobkovsky AE, Wolf YI, Koonin EV. Quantifying the similarity of monotonic trajectories in rough and smooth fitness landscapes. MOLECULAR BIOSYSTEMS 2013; 9:1627-31. [PMID: 23460358 DOI: 10.1039/c3mb25553k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
When selection is strong and mutations are rare, evolution can be thought of as an uphill trajectory in a rugged fitness landscape. In this context the fitness landscape is a directed acyclic graph in which nodes are genotypes and edges lead from lower to higher fitness genotypes that differ by a single mutation. Because the space of genotypes is vastly multi-dimensional, classification of fitness landscapes is challenging. Many proposed summary characteristics of fitness landscapes attempt to quantify biologically relevant and intuitive notions such as roughness or peak accessibility in alternative ways. Here we explore, in different types of landscapes, the behavior of the recently introduced mean path divergence which quantifies the degree of similarity among evolutionary trajectories with the same endpoints. We find that monotonic trajectories in empirical and model fitness landscapes are significantly more constrained, with low median path divergence, than those in purely additive landscapes. By contrast, transcription factor sequence specificity (aptamer binding affinity) landscapes are markedly smoother and allow substantial variability in monotonic paths that can be greater than that in fully additive landscapes. We propose that the smoothness of the specificity landscapes is a consequence of the simple dependence of the transcription factor binding affinity on the aptamer sequence in contrast to the complex sequence-fitness mapping in folding landscapes.
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Affiliation(s)
- Alexander E Lobkovsky
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894, USA
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14
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Cooperative binding of transcription factors promotes bimodal gene expression response. PLoS One 2012; 7:e44812. [PMID: 22984566 PMCID: PMC3440358 DOI: 10.1371/journal.pone.0044812] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 08/13/2012] [Indexed: 12/14/2022] Open
Abstract
In the present work we extend and analyze the scope of our recently proposed stochastic model for transcriptional regulation, which considers an arbitrarily complex cis-regulatory system using only elementary reactions. Previously, we determined the role of cooperativity on the intrinsic fluctuations of gene expression for activating transcriptional switches, by means of master equation formalism and computer simulation. This model allowed us to distinguish between two cooperative binding mechanisms and, even though the mean expression levels were not affected differently by the acting mechanism, we showed that the associated fluctuations were different. In the present generalized model we include other regulatory functions in addition to those associated to an activator switch. Namely, we introduce repressive regulatory functions and two theoretical mechanisms that account for the biphasic response that some cis-regulatory systems show to the transcription factor concentration. We have also extended our previous master equation formalism in order to include protein production by stochastic translation of mRNA. Furthermore, we examine the graded/binary scenarios in the context of the interaction energy between transcription factors. In this sense, this is the first report to show that the cooperative binding of transcription factors to DNA promotes the "all-or-none" phenomenon observed in eukaryotic systems. In addition, we confirm that gene expression fluctuation levels associated with one of two cooperative binding mechanism never exceed the fluctuation levels of the other.
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15
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Mapping the Transition State for DNA Bending by IHF. J Mol Biol 2012; 418:300-15. [DOI: 10.1016/j.jmb.2012.02.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 02/14/2012] [Accepted: 02/17/2012] [Indexed: 01/01/2023]
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16
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Chène P. Can biochemistry drive drug discovery beyond simple potency measurements? Drug Discov Today 2012; 17:388-95. [DOI: 10.1016/j.drudis.2012.01.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 01/23/2012] [Accepted: 01/25/2012] [Indexed: 10/14/2022]
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17
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Boryskina OP, Tkachenko MY, Shestopalova AV. Protein-DNA complexes: specificity and DNA readout mechanisms. ACTA ACUST UNITED AC 2011. [DOI: 10.7124/bc.00007c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- O. P. Boryskina
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine
| | - M. Yu. Tkachenko
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine
| | - A. V. Shestopalova
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine
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18
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Brown C, Campos-León K, Strickland M, Williams C, Fairweather V, Brady RL, Crump MP, Gaston K. Protein flexibility directs DNA recognition by the papillomavirus E2 proteins. Nucleic Acids Res 2010; 39:2969-80. [PMID: 21131281 PMCID: PMC3074142 DOI: 10.1093/nar/gkq1217] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Although DNA flexibility is known to play an important role in DNA–protein interactions, the importance of protein flexibility is less well understood. Here, we show that protein dynamics are important in DNA recognition using the well-characterized human papillomavirus (HPV) type 6 E2 protein as a model system. We have compared the DNA binding properties of the HPV 6 E2 DNA binding domain (DBD) and a mutant lacking two C-terminal leucine residues that form part of the hydrophobic core of the protein. Deletion of these residues results in increased specific and non-specific DNA binding and an overall decrease in DNA binding specificity. Using 15N NMR relaxation and hydrogen/deuterium exchange, we demonstrate that the mutation results in increased flexibility within the hydrophobic core and loop regions that orient the DNA binding helices. Stopped-flow kinetic studies indicate that increased flexibility alters DNA binding by increasing initial interactions with DNA but has little or no effect on the structural rearrangements that follow this step. Taken together these data demonstrate that subtle changes in protein dynamics have a major influence on protein–DNA interactions.
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Affiliation(s)
- Craig Brown
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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19
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Dellarole M, Sánchez IE, de Prat Gay G. Thermodynamics of cooperative DNA recognition at a replication origin and transcription regulatory site. Biochemistry 2010; 49:10277-86. [PMID: 21047141 PMCID: PMC3091369 DOI: 10.1021/bi1014908] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
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Binding cooperativity guides the formation of protein−nucleic acid complexes, in particular those that are highly regulated such as replication origins and transcription sites. Using the DNA binding domain of the origin binding and transcriptional regulator protein E2 from human papillomavirus type 16 as model, and through isothermal titration calorimetry analysis, we determined a positive, entropy-driven cooperativity upon binding of the protein to its cognate tandem double E2 site. This cooperativity is associated with a change in DNA structure, where the overall B conformation is maintained. Two homologous E2 domains, those of HPV18 and HPV11, showed that the enthalpic−entropic components of the reaction and DNA deformation can diverge. Because the DNA binding helix is almost identical in the three domains, the differences must lie dispersed throughout this unique dimeric β-barrel fold. This is in surprising agreement with previous results for this domain, which revealed a strong coupling between global dynamics and DNA recognition.
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Affiliation(s)
- Mariano Dellarole
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-Conicet, Patricias Argentinas 435, Buenos Aires, Argentina
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Sánchez IE, Ferreiro DU, Gay GDP. Mutational analysis of kinetic partitioning in protein folding and protein-DNA binding. Protein Eng Des Sel 2010; 24:179-84. [PMID: 20876193 DOI: 10.1093/protein/gzq064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Kinetic partitioning between competing routes is present in many biological processes. Here, we propose a methodology to characterize kinetic partitioning through site-directed mutagenesis and apply it to parallel routes for unfolding of the TI I27 protein and for recognition of its target DNA by the human papillomavirus E2 protein. The balance between the two competing reaction routes can be quantified by the partitioning constant K(p). K(p) is easily modulated by point mutations, opening the way for the rational design of kinetic partitioning. Conserved wild-type residues strongly favor one of the two competing reactions, suggesting that in these systems there is an evolutionary pressure to shift partitioning towards a certain route. The mutations with the largest effects on partitioning cluster together in space, defining the protein regions most relevant for the modulation of partitioning. Such regions are neither fully coincident with nor strictly segregated from the regions that are important from each competing reaction. We dissected the mutational effects on partitioning into the contributions from each competing route using a new parameter called pi-value. The results suggest how the design of kinetic partitioning may be approached in each case.
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Affiliation(s)
- Ignacio E Sánchez
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina.
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21
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Ballin JD, Prevas JP, Ross CR, Toth EA, Wilson GM, Record MT. Contributions of the histidine side chain and the N-terminal alpha-amino group to the binding thermodynamics of oligopeptides to nucleic acids as a function of pH. Biochemistry 2010; 49:2018-30. [PMID: 20108951 DOI: 10.1021/bi902027z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Interactions of histidine with nucleic acid phosphates and histidine pK(a) shifts make important contributions to many protein-nucleic acid binding processes. To characterize these phenomena in simplified systems, we quantified binding of a histidine-containing model peptide HWKK ((+)NH(3)-His-Trp-Lys-Lys-NH(2)) and its lysine analogue KWKK ((+)NH(3)-Lys-Trp-Lys-Lys-NH(2)) to a single-stranded RNA model, polyuridylate (polyU), by changes in tryptophan fluorescence as a function of salt concentration and pH. For both HWKK and KWKK, equilibrium binding constants, K(obs), and magnitudes of log-log salt derivatives, SK(obs) identical with (partial differential logK(obs)/partial differential log[Na(+)]), decreased with increasing pH in the manner expected for a titration curve model in which deprotonation of the histidine and alpha-amino groups weakens binding and reduces its salt-dependence. Fully protonated HWKK and KWKK exhibit the same K(obs) and SK(obs) within uncertainty, and these SK(obs) values are consistent with limiting-law polyelectrolyte theory for +4 cationic oligopeptides binding to single-stranded nucleic acids. The pH-dependence of HWKK binding to polyU provides no evidence for pK(a) shifts nor any requirement for histidine protonation, in stark contrast to the thermodynamics of coupled protonation often seen for these cationic residues in the context of native protein structure where histidine protonation satisfies specific interactions (e.g., salt-bridge formation) within highly complementary binding interfaces. The absence of pK(a) shifts in our studies indicates that additional Coulombic interactions across the nonspecific-binding interface between RNA and protonated histidine or the alpha-amino group are not sufficient to promote proton uptake for these oligopeptides. We present our findings in the context of hydration models for specific vs nonspecific nucleic acid binding.
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Affiliation(s)
- Jeff D Ballin
- Department of Biochemistry and Molecular Biology and Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
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22
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Abstract
Protein recognition of DNA sites is a primary event for gene function. Its ultimate mechanistic understanding requires an integrated structural, dynamic, kinetic, and thermodynamic dissection that is currently limited considering the hundreds of structures of protein-DNA complexes available. We describe a protein-DNA-binding pathway in which an initial, diffuse, transition state ensemble with some nonnative contacts is followed by formation of extensive nonnative interactions that drive the system into a kinetic trap. Finally, nonnative contacts are slowly rearranged into native-like interactions with the DNA backbone. Dissimilar protein-DNA interfaces that populate along the DNA-binding route are explained by a temporary degeneracy of protein-DNA interactions, centered on "dual-role" residues. The nonnative species slow down the reaction allowing for extended functionality.
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Abstract
Biomolecular folding and function are often coupled. During molecular recognition events, one of the binding partners may transiently or partially unfold, allowing more rapid access to a binding site. We describe a simple model for this fly-casting mechanism based on the capillarity approximation and polymer chain statistics. The model shows that fly casting is most effective when the protein unfolding barrier is small and the part of the chain which extends toward the target is relatively rigid. These features are often seen in known examples of fly casting in protein-DNA binding. Simulations of protein-DNA binding based on well-funneled native-topology models with electrostatic forces confirm the trends of the analytical theory.
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Wetzler DE, Gallo M, Melis R, Eliseo T, Nadra AD, Ferreiro DU, Paci M, Sánchez IE, Cicero DO, de Prat Gay G. A strained DNA binding helix is conserved for site recognition, folding nucleation, and conformational modulation. Biopolymers 2009; 91:432-43. [PMID: 19156829 DOI: 10.1002/bip.21146] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nucleic acid recognition is often mediated by alpha-helices or disordered regions that fold into alpha-helix on binding. A peptide bearing the DNA recognition helix of HPV16 E2 displays type II polyproline (PII) structure as judged by pH, temperature, and solvent effects on the CD spectra. NMR experiments indicate that the canonical alpha-helix is stabilized at the N-terminus, while the PII forms at the C-terminus half of the peptide. Re-examination of the dihedral angles of the DNA binding helix in the crystal structure and analysis of the NMR chemical shift indexes confirm that the N-terminus half is a canonical alpha-helix, while the C-terminal half adopts a 3(10) helix structure. These regions precisely match two locally driven folding nucleii, which partake in the native hydrophobic core and modulate a conformational switch in the DNA binding helix. The peptide shows only weak and unspecific residual DNA binding, 10(4)-fold lower affinity, and 500-fold lower discrimination capacity compared with the domain. Thus, the precise side chain conformation required for modulated and tight physiological binding by HPV E2 is largely determined by the noncanonical strained alpha-helix conformation, "presented" by this unique architecture. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 432-443, 2009.
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Affiliation(s)
- Diana E Wetzler
- Fundación Instituto Leloir and IIBBA-CONICET, Patricias Argentinas 435 (C1405BWE), Buenos Aires, Argentina
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Eliseo T, Sánchez IE, Nadra AD, Dellarole M, Paci M, de Prat Gay G, Cicero DO. Indirect DNA Readout on the Protein Side: Coupling between Histidine Protonation, Global Structural Cooperativity, Dynamics, and DNA Binding of the Human Papillomavirus Type 16 E2C Domain. J Mol Biol 2009; 388:327-44. [PMID: 19285507 DOI: 10.1016/j.jmb.2009.03.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 03/06/2009] [Accepted: 03/06/2009] [Indexed: 11/26/2022]
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