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Yeh F, Jara-Oseguera A, Aldrich RW. Implications of a temperature-dependent heat capacity for temperature-gated ion channels. Proc Natl Acad Sci U S A 2023; 120:e2301528120. [PMID: 37279277 PMCID: PMC10268252 DOI: 10.1073/pnas.2301528120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 04/26/2023] [Indexed: 06/08/2023] Open
Abstract
Temperature influences dynamics and state-equilibrium distributions in all molecular processes, and only a relatively narrow range of temperatures is compatible with life-organisms must avoid temperature extremes that can cause physical damage or metabolic disruption. Animals evolved a set of sensory ion channels, many of them in the family of transient receptor potential cation channels that detect biologically relevant changes in temperature with remarkable sensitivity. Depending on the specific ion channel, heating or cooling elicits conformational changes in the channel to enable the flow of cations into sensory neurons, giving rise to electrical signaling and sensory perception. The molecular mechanisms responsible for the heightened temperature-sensitivity in these ion channels, as well as the molecular adaptations that make each channel specifically heat- or cold-activated, are largely unknown. It has been hypothesized that a heat capacity difference (ΔCp) between two conformational states of these biological thermosensors can drive their temperature-sensitivity, but no experimental measurements of ΔCp have been achieved for these channel proteins. Contrary to the general assumption that the ΔCp is constant, measurements from soluble proteins indicate that the ΔCp is likely to be a function of temperature. By investigating the theoretical consequences for a linearly temperature-dependent ΔCp on the open-closed equilibrium of an ion channel, we uncover a range of possible channel behaviors that are consistent with experimental measurements of channel activity and that extend beyond what had been generally assumed to be possible for a simple two-state model, challenging long-held assumptions about ion channel gating models at equilibrium.
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Affiliation(s)
- Frank Yeh
- Institute for Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Neuroscience, University of Texas at Austin, Austin, TX78712
| | - Andrés Jara-Oseguera
- Institute for Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX78712
| | - Richard W. Aldrich
- Institute for Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Neuroscience, University of Texas at Austin, Austin, TX78712
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2
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POT1 stability and binding measured by fluorescence thermal shift assays. PLoS One 2021; 16:e0245675. [PMID: 33784306 PMCID: PMC8009405 DOI: 10.1371/journal.pone.0245675] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/03/2021] [Indexed: 11/19/2022] Open
Abstract
The protein POT1 (Protection of Telomeres 1) is an integral part of the shelterin complex that protects the ends of human chromosomes from degradation or end fusions. It is the only component of shelterin that binds single-stranded DNA. We describe here the application of two separate fluorescent thermal shift assays (FTSA) that provide quantitative biophysical characterization of POT1 stability and its interactions. The first assay uses Sypro Orange™ and monitors the thermal stability of POT1 and its binding under a variety of conditions. This assay is useful for the quality control of POT1 preparations, for biophysical characterization of its DNA binding and, potentially, as an efficient screening tool for binding of small molecule drug candidates. The second assay uses a FRET-labeled human telomeric G-quadruplex structure that reveals the effects of POT1 binding on thermal stability from the DNA frame of reference. These complementary assays provide efficient biophysical approaches for the quantitative characterization of multiple aspects of POT1 structure and function. The results from these assays provide thermodynamics details of POT1 folding, the sequence selectivity of its DNA binding and the thermodynamic profile for its binding to its preferred DNA binding sequence. Most significantly, results from these assays elucidate two mechanisms for the inhibition of POT1 -DNA interactions. The first is by competitive inhibition at the POT1 DNA binding site. The second is indirect and is by stabilization of G-quadruplex formation within the normal POT1 single-stranded DNA sequence to prevent POT1 binding.
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3
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Achazi K, Haag R, Ballauff M, Dernedde J, Kizhakkedathu JN, Maysinger D, Multhaup G. Understanding the Interaction of Polyelectrolyte Architectures with Proteins and Biosystems. Angew Chem Int Ed Engl 2021; 60:3882-3904. [PMID: 32589355 PMCID: PMC7894192 DOI: 10.1002/anie.202006457] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Indexed: 02/06/2023]
Abstract
The counterions neutralizing the charges on polyelectrolytes such as DNA or heparin may dissociate in water and greatly influence the interaction of such polyelectrolytes with biomolecules, particularly proteins. In this Review we give an overview of studies on the interaction of proteins with polyelectrolytes and how this knowledge can be used for medical applications. Counterion release was identified as the main driving force for the binding of proteins to polyelectrolytes: Patches of positive charge become multivalent counterions of the polyelectrolyte and lead to the release of counterions from the polyelectrolyte and a concomitant increase in entropy. This is shown from investigations on the interaction of proteins with natural and synthetic polyelectrolytes. Special emphasis is paid to sulfated dendritic polyglycerols (dPGS). The Review demonstrates that we are moving to a better understanding of charge-charge interactions in systems of biological relevance. Research along these lines will aid and promote the design of synthetic polyelectrolytes for medical applications.
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Affiliation(s)
- Katharina Achazi
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
| | - Rainer Haag
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
| | - Matthias Ballauff
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
- IRIS AdlershofHumboldt Universität zu BerlinZum Grossen Windkanal 612489BerlinGermany
| | - Jens Dernedde
- Charité-Universitätsmedizin BerlinInstitute of Laboratory MedicineClinical Chemistry, and PathobiochemistryCVK Augustenburger Platz 113353BerlinGermany
| | - Jayachandran N. Kizhakkedathu
- Centre for Blood ResearchDepartment of Pathology and Laboratory MedicineLife Science InstituteDepartment of ChemistrySchool of Biomedical EngineeringUniversity of British ColumbiaVancouverV6T 1Z3Canada
| | - Dusica Maysinger
- Department of Pharmacology and TherapeuticsMcGill UniversityMontrealH3G 1Y6Canada
| | - Gerd Multhaup
- Department of Pharmacology and TherapeuticsMcGill UniversityMontrealH3G 1Y6Canada
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4
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Gliech CR, Holland AJ. Keeping track of time: The fundamentals of cellular clocks. J Cell Biol 2020; 219:e202005136. [PMID: 32902596 PMCID: PMC7594491 DOI: 10.1083/jcb.202005136] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 12/13/2022] Open
Abstract
Biological timekeeping enables the coordination and execution of complex cellular processes such as developmental programs, day/night organismal changes, intercellular signaling, and proliferative safeguards. While these systems are often considered separately owing to a wide variety of mechanisms, time frames, and outputs, all clocks are built by calibrating or delaying the rate of biochemical reactions and processes. In this review, we explore the common themes and core design principles of cellular clocks, giving special consideration to the challenges associated with building timers from biochemical components. We also outline how evolution has coopted time to increase the reliability of a diverse range of biological systems.
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Affiliation(s)
| | - Andrew J. Holland
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD
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5
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Achazi K, Haag R, Ballauff M, Dernedde J, Kizhakkedathu JN, Maysinger D, Multhaup G. Wechselwirkung von Polyelektrolyt‐Architekturen mit Proteinen und Biosystemen. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006457] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Katharina Achazi
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Rainer Haag
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Matthias Ballauff
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
- IRIS Adlershof Humboldt-Universität zu Berlin Zum Großen Windkanal 6 12489 Berlin Deutschland
| | - Jens Dernedde
- Charité-Universitätsmedizin Berlin Institut für Laboratoriumsmedizin Klinische Chemie und Pathobiochemie CVK Augustenburger Platz 1 13353 Berlin Deutschland
| | - Jayachandran N. Kizhakkedathu
- Centre for Blood Research Department of Pathology and Laboratory Medicine Life Science Institute Department of Chemistry School of Biomedical Engineering University of British Columbia Vancouver V6T 1Z3 Kanada
| | - Dusica Maysinger
- Department of Pharmacology and Therapeutics McGill University Montreal H3G 1Y6 Kanada
| | - Gerd Multhaup
- Department of Pharmacology and Therapeutics McGill University Montreal H3G 1Y6 Kanada
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6
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Manka SW, Brew K. Thermodynamic and Mechanistic Insights into Coupled Binding and Unwinding of Collagen by Matrix Metalloproteinase 1. J Mol Biol 2020; 432:5985-5993. [PMID: 33058879 DOI: 10.1016/j.jmb.2020.10.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/06/2020] [Accepted: 10/06/2020] [Indexed: 10/23/2022]
Abstract
Local unwinding of the collagen triple helix is a necessary step for initiating the collagen degradation cascade in extracellular matrices. A few matrix metalloproteinases (MMPs) are known to support this key process, but its energetic aspects remain unknown. Here, we captured the thermodynamics of the triple helix unwinding by monitoring interactions between a collagen peptide and MMP-1(E200A) - an active-site mutant of an archetypal vertebrate collagenase - at increasing temperatures, using isothermal titration calorimetry (ITC). Coupled binding and unwinding manifests as a curved relationship between the total enthalpy change and temperature of the reaction, producing increasingly negative heat capacity change (ΔΔCp ≈ -36.3 kcal/molK2). A specially designed solid-phase binding and cleavage assay (SPBCA) reported strain in the catalytically relevant unwound state, suggesting that this state is distinct from the horizon of sampled conformations of the collagenase-susceptible site. MMP-1 appears to blend selected fit with induced fit mechanisms to catalyse collagen unwinding prior to cleavage of individual collagen chains.
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Affiliation(s)
- Szymon W Manka
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Kennedy Institute of Rheumatology, University of Oxford, Oxford, UK.
| | - Keith Brew
- Department of Biomedical Science, Florida Atlantic University, Boca Raton, FL 33431, USA
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7
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Xu X, Ballauff M. Interaction of Lysozyme with a Dendritic Polyelectrolyte: Quantitative Analysis of the Free Energy of Binding and Comparison to Molecular Dynamics Simulations. J Phys Chem B 2019; 123:8222-8231. [DOI: 10.1021/acs.jpcb.9b07448] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Xiao Xu
- School of Chemical Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, 210094 Nanjing, P. R. China
| | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
- Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
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8
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Xu X, Angioletti-Uberti S, Lu Y, Dzubiella J, Ballauff M. Interaction of Proteins with Polyelectrolytes: Comparison of Theory to Experiment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5373-5391. [PMID: 30095921 DOI: 10.1021/acs.langmuir.8b01802] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We discuss recent investigations of the interaction of polyelectrolytes with proteins. In particular, we review our recent studies on the interaction of simple proteins such as human serum albumin (HSA) and lysozyme with linear polyelectrolytes, charged dendrimers, charged networks, and polyelectrolyte brushes. In all cases discussed here, we combined experimental work with molecular dynamics (MD) simulations and mean-field theories. In particular, isothermal titration calorimetry (ITC) has been employed to obtain the respective binding constants Kb and the Gibbs free energy of binding. MD simulations with explicit counterions but implicit water demonstrate that counterion release is the main driving force for the binding of proteins to strongly charged polyelectrolytes: patches of positive charges located on the surface of the protein become multivalent counterions of the polyelectrolyte, thereby releasing a number of counterions condensed on the polyelectrolyte. The binding Gibbs free energy due to counterion release is predicted to scale with the logarithm of the salt concentration in the system, which is verified by both simulations and experiment. In several cases, namely, for the interaction of proteins with linear polyelectrolytes and highly charged hydrophilic dendrimers, the binding constant could be calculated from simulations to very good approximation. This finding demonstrated that in these cases explicit hydration effects do not contribute to the Gibbs free energy of binding. The Gibbs free energy can also be used to predict the kinetics of protein uptake by microgels for a given system by applying dynamic density functional theory. The entire discussion demonstrates that the direct comparison of theory with experiments can lead to a full understanding of the interaction of proteins with charged polymers. Possible implications for applications, such as drug design, are discussed.
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Affiliation(s)
- Xiao Xu
- School of Chemical Engineering , Nanjing University of Science and Technology , 200 Xiao Ling Wei , Nanjing 210094 , P. R. China
| | - Stefano Angioletti-Uberti
- Department of Materials , Imperial College London , London SW7 2AZ - UK , U.K
- International Research Centre for Soft Matter , Beijing University of Chemical Technology , 100099 Beijing , PR China
| | - Yan Lu
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institute of Chemistry , University of Potsdam , 14467 Potsdam , Germany
| | - Joachim Dzubiella
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Physikalisches Institut , Albert-Ludwigs-Universität , 79104 Freiburg , Germany
| | - Matthias Ballauff
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institut für Physik , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
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9
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Kocaman S, Serpersu EH. The Thermodynamics of Ligand Binding to the Aminoglycoside O-Nucleotidyltransferase(4′) and Variants Yields Clues about Thermophilic Properties. Biochemistry 2019; 58:1579-1586. [DOI: 10.1021/acs.biochem.8b01201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Seda Kocaman
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Engin H. Serpersu
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, Tennessee 37996, United States
- Graduate School of Genome Science and Technology, The University of Tennessee and Oak Ridge National Laboratories, Knoxville, Tennessee 37996, United States
- National Science Foundation, 2415 Eisenhower Avenue, Alexandria, Virginia 22314, United States
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10
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Structural insights into chaperone addiction of toxin-antitoxin systems. Nat Commun 2019; 10:782. [PMID: 30770830 PMCID: PMC6377645 DOI: 10.1038/s41467-019-08747-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 01/10/2019] [Indexed: 12/20/2022] Open
Abstract
SecB chaperones assist protein export by binding both unfolded proteins and the SecA motor. Certain SecB homologs can also control toxin-antitoxin (TA) systems known to modulate bacterial growth in response to stress. In such TA-chaperone (TAC) systems, SecB assists the folding and prevents degradation of the antitoxin, thus facilitating toxin inhibition. Chaperone dependency is conferred by a C-terminal extension in the antitoxin known as chaperone addiction (ChAD) sequence, which makes the antitoxin aggregation-prone and prevents toxin inhibition. Using TAC of Mycobacterium tuberculosis, we present the structure of a SecB-like chaperone bound to its ChAD peptide. We find differences in the binding interfaces when compared to SecB–SecA or SecB-preprotein complexes, and show that the antitoxin can reach a functional form while bound to the chaperone. This work reveals how chaperones can use discrete surface binding regions to accommodate different clients or partners and thereby expand their substrate repertoire and functions. SecB homologs can be associated with stress-responsive type II toxin–antitoxin (TA) systems and form tripartite toxin-antitoxin-chaperone systems (TAC). Here the authors provide structural insights into TACs by presenting the crystal structure of the M. tuberculosis TA-associated SecB chaperone in complex with the C-terminal ChAD (chaperone addiction) extension of the antitoxin HigA1.
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11
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Morris G, Stoychev S, Naicker P, Dirr HW, Fanucchi S. The forkhead domain hinge-loop plays a pivotal role in DNA binding and transcriptional activity of FOXP2. Biol Chem 2018; 399:881-893. [DOI: 10.1515/hsz-2018-0185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 04/26/2018] [Indexed: 01/01/2023]
Abstract
Abstract
Forkhead box (FOX) proteins are a ubiquitously expressed family of transcription factors that regulate the development and differentiation of a wide range of tissues in animals. The FOXP subfamily members are the only known FOX proteins capable of forming domain-swapped forkhead domain (FHD) dimers. This is proposed to be due to an evolutionary mutation (P539A) that lies in the FHD hinge loop, a key region thought to fine-tune DNA sequence specificity in the FOX transcription factors. Considering the importance of the hinge loop in both the dimerisation mechanism of the FOXP FHD and its role in tuning DNA binding, a detailed investigation into the implications of mutations within this region could provide important insight into the evolution of the FOX family. Isothermal titration calorimetry and hydrogen exchange mass spectroscopy were used to study the thermodynamic binding signature and changes in backbone dynamics of FOXP2 FHD DNA binding. Dual luciferase reporter assays were performed to study the effect that the hinge-loop mutation has on FOXP2 transcriptional activity in vivo. We demonstrate that the change in dynamics of the hinge-loop region of FOXP2 alters the energetics and mechanism of DNA binding highlighting the critical role of hinge loop mutations in regulating DNA binding characteristics of the FOX proteins.
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Affiliation(s)
- Gavin Morris
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology , University of the Witwatersrand, 1 Jan Smuts Ave, Braamfontein , 2050 Johannesburg, Gauteng , South Africa
| | - Stoyan Stoychev
- CSIR Biosciences, CSIR, Meiring Naude Road , Brummeria, 0001 Pretoria, Gauteng , South Africa
| | - Previn Naicker
- CSIR Biosciences, CSIR, Meiring Naude Road , Brummeria, 0001 Pretoria, Gauteng , South Africa
| | - Heini W. Dirr
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology , University of the Witwatersrand, 1 Jan Smuts Ave, Braamfontein , 2050 Johannesburg, Gauteng , South Africa
| | - Sylvia Fanucchi
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology , University of the Witwatersrand, 1 Jan Smuts Ave, Braamfontein , 2050 Johannesburg, Gauteng , South Africa
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12
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Lee AL, Sapienza PJ. Thermodynamic and NMR Assessment of Ligand Cooperativity and Intersubunit Communication in Symmetric Dimers: Application to Thymidylate Synthase. Front Mol Biosci 2018; 5:47. [PMID: 29888227 PMCID: PMC5981203 DOI: 10.3389/fmolb.2018.00047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 04/23/2018] [Indexed: 01/17/2023] Open
Abstract
Thymidylate synthase (TS) is a homodimeric enzyme with evidence for negative regulation of one protomer while the other protomer acts on substrate, so called half-the-sites reactivity. The mechanisms by which multisubunit allosteric proteins communicate between protomers is not well understood, and the simplicity of dimeric systems has advantages for observing conformational and dynamic processes that functionally connect distance-separated active sites. This review considers progress in overcoming the inherent challenges of accurate thermodynamic and atomic-resolution characterization of interprotomer communication mechanisms in symmetric protein dimers, with TS used as an example. Isothermal titration calorimetry (ITC) is used to measure ligand binding cooperativity, even in cases where the two binding enthalpies are similar, and NMR spectroscopy is used to detect site-specific changes occurring in the two protomers. The NMR approach makes use of mixed-labeled dimers, enabling protomer-specific detection of signals in the singly ligated state. The rich informational content of the NMR signals from the singly ligated state, relative to the apo and saturated states, requires new considerations that do not arise in simple cases of 1:1 protein-ligand interactions.
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Affiliation(s)
- Andrew L Lee
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Paul J Sapienza
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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13
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On the link between conformational changes, ligand binding and heat capacity. Biochim Biophys Acta Gen Subj 2016; 1860:868-878. [DOI: 10.1016/j.bbagen.2015.10.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/09/2015] [Accepted: 10/10/2015] [Indexed: 10/22/2022]
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14
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Basu A, Kumar GS. Targeting proteins with toxic azo dyes: a microcalorimetric characterization of the interaction of the food colorant amaranth with serum proteins. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:7955-7962. [PMID: 25033020 DOI: 10.1021/jf5025278] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The interaction of amaranth with two homologous serum albumins from human and bovine (HSA and BSA) was studied by microcalorimetry. The binding stoichiometry for the complexation of amaranth to both BSA and HSA was around 1, and the equilibrium constants were (5.79 ± 0.07) × 10(5) and (1.76 ± 0.05) × 10(5) M(-1), respectively. The binding reaction to HSA at 298.15 K was driven by a large negative enthalpic contribution and a small but positive entropic contribution, while to BSA, it was entirely enthalpy-driven and the entropic contribution was unfavorable. Parsing of the standard molar Gibbs energy revealed that the complexation was dominated by non-polyelectrolytic forces. Temperature-dependent isothermal titration calorimetry studies revealed that the enthalpic contribution increased and the entropic contribution decreased with the rise in the temperature but the Gibbs energy change remained almost unaltered. Differential scanning calorimetry results revealed that the binding reaction stabilized the serum albumins significantly against thermal unfolding.
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Affiliation(s)
- Anirban Basu
- Biophysical Chemistry Laboratory, Chemistry Division, Council of Scientific and Industrial Research (CSIR)-Indian Institute of Chemical Biology , Kolkata 700 032, India
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15
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Temperature-dependence of the DnaA-DNA interaction and its effect on the autoregulation of dnaA expression. Biochem J 2013; 449:333-41. [PMID: 23092251 DOI: 10.1042/bj20120876] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The DnaA protein is a key factor for the regulation of the timing and synchrony of initiation of bacterial DNA replication. The transcription of the dnaA gene in Escherichia coli is regulated by two promoters, dnaAP1 and dnaAP2. The region between these two promoters contains several DnaA-binding sites that have been shown to play an important role in the negative auto-regulation of dnaA expression. The results obtained in the present study using an in vitro and in vivo quantitative analysis of the effect of mutations to the high-affinity DnaA sites reveal an additional effect of positive autoregulation. We investigated the role of transcription autoregulation in the change of dnaA expression as a function of temperature. While negative auto-regulation is lost at dnaAP1, the effects of both positive and negative autoregulation are maintained at the dnaAP2 promoter upon lowering the growth temperature. These observations can be explained by the results obtained in vitro showing a difference in the temperature-dependence of DnaA-ATP binding to its high- and low-affinity sites, resulting in a decrease in DnaA-ATP oligomerization at lower temperatures. The results of the present study underline the importance of the role for autoregulation of gene expression in the cellular adaptation to different growth temperatures.
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16
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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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17
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Analysis of Free Energy Versus Temperature Curves in Protein Folding and Macromolecular Interactions. Methods Enzymol 2011; 488:219-38. [DOI: 10.1016/b978-0-12-381268-1.00009-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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18
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Portolés S, Más P. The functional interplay between protein kinase CK2 and CCA1 transcriptional activity is essential for clock temperature compensation in Arabidopsis. PLoS Genet 2010; 6:e1001201. [PMID: 21079791 PMCID: PMC2973838 DOI: 10.1371/journal.pgen.1001201] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 10/07/2010] [Indexed: 01/17/2023] Open
Abstract
Circadian rhythms are daily biological oscillations driven by an endogenous mechanism known as circadian clock. The protein kinase CK2 is one of the few clock components that is evolutionary conserved among different taxonomic groups. CK2 regulates the stability and nuclear localization of essential clock proteins in mammals, fungi, and insects. Two CK2 regulatory subunits, CKB3 and CKB4, have been also linked with the Arabidopsis thaliana circadian system. However, the biological relevance and the precise mechanisms of CK2 function within the plant clockwork are not known. By using ChIP and Double-ChIP experiments together with in vivo luminescence assays at different temperatures, we were able to identify a temperature-dependent function for CK2 modulating circadian period length. Our study uncovers a previously unpredicted mechanism for CK2 antagonizing the key clock regulator CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1). CK2 activity does not alter protein accumulation or subcellular localization but interferes with CCA1 binding affinity to the promoters of the oscillator genes. High temperatures enhance the CCA1 binding activity, which is precisely counterbalanced by the CK2 opposing function. Altering this balance by over-expression, mutation, or pharmacological inhibition affects the temperature compensation profile, providing a mechanism by which plants regulate circadian period at changing temperatures. Therefore, our study establishes a new model demonstrating that two opposing and temperature-dependent activities (CCA1-CK2) are essential for clock temperature compensation in Arabidopsis.
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Affiliation(s)
- Sergi Portolés
- Consortium CSIC-IRTA-UAB, Centre for Research in Agricultural Genomics (CRAG), Department of Plant Molecular Genetics, Barcelona, Spain
| | - Paloma Más
- Consortium CSIC-IRTA-UAB, Centre for Research in Agricultural Genomics (CRAG), Department of Plant Molecular Genetics, Barcelona, Spain
- * E-mail:
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Pliska V. Thermodynamic descriptors, profiles and driving forces in membrane receptor-ligand interactions. J Recept Signal Transduct Res 2010; 30:454-68. [DOI: 10.3109/10799893.2010.515594] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Wowor AJ, Datta K, Brown HS, Thompson GS, Ray S, Grove A, LiCata VJ. Thermodynamics of the DNA structural selectivity of the Pol I DNA polymerases from Escherichia coli and Thermus aquaticus. Biophys J 2010; 98:3015-24. [PMID: 20550914 DOI: 10.1016/j.bpj.2010.03.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/10/2010] [Accepted: 03/12/2010] [Indexed: 10/19/2022] Open
Abstract
Understanding the thermodynamics of substrate selection by DNA polymerase I is important for characterizing the balance between replication and repair for this enzyme in vivo. Due to their sequence and structural similarities, Klenow and Klentaq, the large fragments of the Pol I DNA polymerases from Escherichia coli and Thermus aquaticus, are considered functional homologs. Klentaq, however, does not have a functional proofreading site. Examination of the DNA binding thermodynamics of Klenow and Klentaq to different DNA structures: single-stranded DNA (ss-DNA), primer-template DNA (pt-DNA), and blunt-end double-stranded DNA (ds-DNA) show that the binding selectivity pattern is similar when examined across a wide range of salt concentration, but can significantly differ at any individual salt concentration. For both proteins, binding of single-stranded DNA shifts from weakest to tightest binding of the three structures as the salt concentration increases. Both Klenow and Klentaq release two to three more ions when binding to pt-DNA and ds-DNA than when binding to ss-DNA. Klenow exhibits significant differences in the Delta C(p) of binding to pt-DNA versus ds-DNA, and a difference in pI for these two complexes, whereas Klentaq does not, suggesting that Klenow and Klentaq discriminate between these two structures differently. Taken together, the data suggest that the two polymerases bind ds-DNA very differently, but that both bind pt-DNA and ss-DNA similarly, despite the absence of a proofreading site in Klentaq.
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Affiliation(s)
- Andy J Wowor
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
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Survey of the year 2008: applications of isothermal titration calorimetry. J Mol Recognit 2010; 23:395-413. [DOI: 10.1002/jmr.1025] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Yu L, Fang J, Wei Y. Characterization of the ligand and DNA binding properties of a putative archaeal regulator ST1710. Biochemistry 2009; 48:2099-108. [PMID: 19166356 DOI: 10.1021/bi801662s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While a rich collection of bacterium-like regulating proteins has been identified in the archaeal genome, few of them have been studied at the molecular level. In this study, we characterized the ligand and DNA binding properties of a putative regulator ST1710 from the archaeon Sulfolobus tokodaii. ST1710 is homologous to the multiple-antibiotic resistance repressor (MarR) family bacterial regulators. The protein consists of a ligand binding site, partially overlapping with a winged helix-turn-helix DNA binding site. We characterized the interactions between ST1710 and three ligands, salicylate, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and ethidium, which bind to bacterial MarRs. The binding affinities of the ligands for ST1710 were comparable to their affinities for the bacterial MarRs. The ligand binding was temperature sensitive and caused conformational changes in ST1710. To investigate the effect of ligand binding on the interaction between ST1710 and DNA, we fluorescently labeled a 47mer dsDNA (ST1) containing a putative ST1710 recognition site and determined the dissociation constant between ST1 and ST1710 using the fluorescence polarization method. The binding affinity almost doubled from 10 degrees C (Kd = 618 +/- 34 nM) to 30 degreesC (Kd = 334 +/- 15 nM), and again from 30 to 50 degrees C (Kd = 189 +/- 9 nM). This result suggests that under the natural living condition (80 degrees C) of S. tokodaii, the binding affinity might increase even further. The presence of CCCP and salicylate suppressed ST1710-ST1 interaction, indicating that ST1710 functioned as a repressor.
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Affiliation(s)
- Linliang Yu
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA
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Baranauskienė L, Petrikaitė V, Matulienė J, Matulis D. Titration calorimetry standards and the precision of isothermal titration calorimetry data. Int J Mol Sci 2009; 10:2752-2762. [PMID: 19582227 PMCID: PMC2705514 DOI: 10.3390/ijms10062752] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 06/01/2009] [Accepted: 06/15/2009] [Indexed: 11/16/2022] Open
Abstract
Current Isothermal Titration Calorimetry (ITC) data in the literature have relatively high errors in the measured enthalpies of protein-ligand binding reactions. There is a need for universal validation standards for titration calorimeters. Several inorganic salt co-precipitation and buffer protonation reactions have been suggested as possible enthalpy standards. The performances of several commercial calorimeters, including the VP-ITC, ITC200, and Nano ITC-III, were validated using these suggested standard reactions.
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Affiliation(s)
| | | | | | - Daumantas Matulis
- Author to whom correspondence should be addressed; E-Mail:
; Tel. +370-5-269-1884; Fax: +370-5-260-2116
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