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Yang M, Shi J, Schlenoff JB. Control of Dynamics in Polyelectrolyte Complexes by Temperature and Salt. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02577] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Mo Yang
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Jianbing Shi
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Joseph B. Schlenoff
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
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2
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Pica A, Graziano G. Shedding light on the extra thermal stability of thermophilic proteins. Biopolymers 2017; 105:856-63. [PMID: 27449333 DOI: 10.1002/bip.22923] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 07/12/2016] [Accepted: 07/20/2016] [Indexed: 11/08/2022]
Abstract
An entropic stabilization mechanism has recently gained attention and credibility as the physical ground for the extra thermal stability of globular proteins from thermophilic microorganisms. An empirical result, obtained from the analysis of thermodynamic data for a large set of proteins, strengthens the general reliability of the theoretical approach originally devised to rationalize the occurrence of cold denaturation [Graziano, PCCP 2014, 16, 21755-21767]. It is shown that this theoretical approach can readily account for the entropic stabilization mechanism. On decreasing the conformational entropy gain associated with denaturation, the thermal stability of a model globular protein increases markedly.
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Affiliation(s)
- Andrea Pica
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, Via Cintia, Napoli, 80126, Italy
| | - Giuseppe Graziano
- Dipartimento di Scienze e Tecnologie, Università del Sannio, Via Port'Arsa 11, Benevento, 82100, Italy.
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De Geyter J, Tsirigotaki A, Orfanoudaki G, Zorzini V, Economou A, Karamanou S. Protein folding in the cell envelope of Escherichia coli. Nat Microbiol 2016; 1:16107. [PMID: 27573113 DOI: 10.1038/nmicrobiol.2016.107] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 06/02/2016] [Indexed: 11/09/2022]
Abstract
While the entire proteome is synthesized on cytoplasmic ribosomes, almost half associates with, localizes in or crosses the bacterial cell envelope. In Escherichia coli a variety of mechanisms are important for taking these polypeptides into or across the plasma membrane, maintaining them in soluble form, trafficking them to their correct cell envelope locations and then folding them into the right structures. The fidelity of these processes must be maintained under various environmental conditions including during stress; if this fails, proteases are called in to degrade mislocalized or aggregated proteins. Various soluble, diffusible chaperones (acting as holdases, foldases or pilotins) and folding catalysts are also utilized to restore proteostasis. These responses can be general, dealing with multiple polypeptides, with functional overlaps and operating within redundant networks. Other chaperones are specialized factors, dealing only with a few exported proteins. Several complex machineries have evolved to deal with binding to, integration in and crossing of the outer membrane. This complex protein network is responsible for fundamental cellular processes such as cell wall biogenesis; cell division; the export, uptake and degradation of molecules; and resistance against exogenous toxic factors. The underlying processes, contributing to our fundamental understanding of proteostasis, are a treasure trove for the development of novel antibiotics, biopharmaceuticals and vaccines.
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Affiliation(s)
- Jozefien De Geyter
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
| | - Alexandra Tsirigotaki
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
| | - Georgia Orfanoudaki
- Institute of Molecular Biology and Biotechnology, FORTH and Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece
| | - Valentina Zorzini
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
| | - Anastassios Economou
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium.,Institute of Molecular Biology and Biotechnology, FORTH and Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece
| | - Spyridoula Karamanou
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
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Iwahara J, Esadze A, Zandarashvili L. Physicochemical Properties of Ion Pairs of Biological Macromolecules. Biomolecules 2015; 5:2435-63. [PMID: 26437440 PMCID: PMC4693242 DOI: 10.3390/biom5042435] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 09/09/2015] [Accepted: 09/11/2015] [Indexed: 11/23/2022] Open
Abstract
Ion pairs (also known as salt bridges) of electrostatically interacting cationic and anionic moieties are important for proteins and nucleic acids to perform their function. Although numerous three-dimensional structures show ion pairs at functionally important sites of biological macromolecules and their complexes, the physicochemical properties of the ion pairs are not well understood. Crystal structures typically show a single state for each ion pair. However, recent studies have revealed the dynamic nature of the ion pairs of the biological macromolecules. Biomolecular ion pairs undergo dynamic transitions between distinct states in which the charged moieties are either in direct contact or separated by water. This dynamic behavior is reasonable in light of the fundamental concepts that were established for small ions over the last century. In this review, we introduce the physicochemical concepts relevant to the ion pairs and provide an overview of the recent advancement in biophysical research on the ion pairs of biological macromolecules.
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Affiliation(s)
- Junji Iwahara
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Alexandre Esadze
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Levani Zandarashvili
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
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Karshikoff A, Nilsson L, Ladenstein R. Rigidity versus flexibility: the dilemma of understanding protein thermal stability. FEBS J 2015; 282:3899-917. [PMID: 26074325 DOI: 10.1111/febs.13343] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/17/2015] [Accepted: 06/09/2015] [Indexed: 01/19/2023]
Abstract
The role of fluctuations in protein thermostability has recently received considerable attention. In the current literature a dualistic picture can be found: thermostability seems to be associated with enhanced rigidity of the protein scaffold in parallel with the reduction of flexible parts of the structure. In contradiction to such arguments it has been shown by experimental studies and computer simulation that thermal tolerance of a protein is not necessarily correlated with the suppression of internal fluctuations and mobility. Both concepts, rigidity and flexibility, are derived from mechanical engineering and represent temporally insensitive features describing static properties, neglecting that relative motion at certain time scales is possible in structurally stable regions of a protein. This suggests that a strict separation of rigid and flexible parts of a protein molecule does not describe the reality correctly. In this work the concepts of mobility/flexibility versus rigidity will be critically reconsidered by taking into account molecular dynamics calculations of heat capacity and conformational entropy, salt bridge networks, electrostatic interactions in folded and unfolded states, and the emerging picture of protein thermostability in view of recently developed network theories. Last, but not least, the influence of high temperature on the active site and activity of enzymes will be considered.
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Affiliation(s)
- Andrey Karshikoff
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Lennart Nilsson
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Rudolf Ladenstein
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
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Abarca F, Gutierrez-Maldonado SE, Parada P, Martinez P, Maass A, Perez-Acle T. Insights on the structure and stability of Licanantase: a trimeric acid-stable coiled-coil lipoprotein from Acidithiobacillus thiooxidans. PeerJ 2014; 2:e457. [PMID: 25165619 PMCID: PMC4137666 DOI: 10.7717/peerj.457] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 06/06/2014] [Indexed: 12/29/2022] Open
Abstract
Licanantase (Lic) is the major component of the secretome of Acidithiobacillus thiooxidans when grown in elemental sulphur. When used as an additive, Lic improves copper recovery from bioleaching processes. However, this recovery enhancement is not fully understood. In this context, our aim is to predict the 3D structure of Lic, to shed light on its structure-function relationships. Bioinformatics analyses on the amino acid sequence of Lic showed a great similarity with Lpp, an Escherichia coli Lipoprotein that can form stable trimers in solution. Lic and Lpp share the secretion motif, intracellular processing and alpha helix structure, as well as the distribution of hydrophobic residues in heptads forming a hydrophobic core, typical of coiled-coil structures. Cross-linking experiments showed the presence of Lic trimers, supporting our predictions. Taking the in vitro and in silico evidence as a whole, we propose that the most probable structure for Lic is a trimeric coiled-coil. According to this prediction, a suitable model for Lic was produced using the de novo algorithm "Rosetta Fold-and-Dock". To assess the structural stability of our model, Molecular Dynamics (MD) and Replica Exchange MD simulations were performed using the structure of Lpp and a 14-alanine Lpp mutant as controls, at both acidic and neutral pH. Our results suggest that Lic was the most stable structure among the studied proteins in both pH conditions. This increased stability can be explained by a higher number of both intermonomer hydrophobic contacts and hydrogen bonds, key elements for the stability of Lic's secondary and tertiary structure.
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Affiliation(s)
- Fernando Abarca
- Computational Biology Lab (DLab), Fundación Ciencia y Vida, Ñuñoa, Santiago, Chile
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Sebastian E. Gutierrez-Maldonado
- Computational Biology Lab (DLab), Fundación Ciencia y Vida, Ñuñoa, Santiago, Chile
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | | | | | - Alejandro Maass
- Mathomics, Center for Mathematical Modeling (CMM) and Center for Genome Regulation (CRG), Universidad de Chile, Santiago, Chile
- Department of Mathematical Engineering, Universidad de Chile, Santiago, Chile
| | - Tomas Perez-Acle
- Computational Biology Lab (DLab), Fundación Ciencia y Vida, Ñuñoa, Santiago, Chile
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
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Karshikoff A, Nilsson L, Foloppe N. Understanding the −C–X1–X2–C– Motif in the Active Site of the Thioredoxin Superfamily: E. coli DsbA and Its Mutants as a Model System. Biochemistry 2013; 52:5730-45. [DOI: 10.1021/bi400500e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrey Karshikoff
- Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str.,
bl. 21, Sofia 1113, Bulgaria
| | - Lennart Nilsson
- Department of Biosciences and
Nutrition, Center for Biosciences, Karolinska Institutet, S-141 83 Huddinge, Sweden
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Nilsson L, Karshikoff A. Multiple pH regime molecular dynamics simulation for pK calculations. PLoS One 2011; 6:e20116. [PMID: 21647418 PMCID: PMC3103538 DOI: 10.1371/journal.pone.0020116] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 04/25/2011] [Indexed: 11/25/2022] Open
Abstract
Ionisation equilibria in proteins are influenced by conformational flexibility, which can in principle be accounted for by molecular dynamics simulation. One problem in this method is the bias arising from the fixed protonation state during the simulation. Its effect is mostly exhibited when the ionisation behaviour of the titratable groups is extrapolated to pH regions where the predetermined protonation state of the protein may not be statistically relevant, leading to conformational sampling that is not representative of the true state. In this work we consider a simple approach which can essentially reduce this problem. Three molecular dynamics structure sets are generated, each with a different protonation state of the protein molecule expected to be relevant at three pH regions, and pK calculations from the three sets are combined to predict pK over the entire pH range of interest. This multiple pH molecular dynamics approach was tested on the GCN4 leucine zipper, a protein for which a full data set of experimental data is available. The pK values were predicted with a mean deviation from the experimental data of 0.29 pH units, and with a precision of 0.13 pH units, evaluated on the basis of equivalent sites in the dimeric GCN4 leucine zipper.
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Affiliation(s)
- Lennart Nilsson
- Department of Biosciences and Nutrition, Center for Biosciences, Karolinska Institutet, Huddinge, Sweden.
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Liu Y, Chapagain PP, Gerstman BS. Stabilization of Native and Non-native Structures by Salt Bridges in a Lattice Model of the GCN4 Leucine Dimer. J Phys Chem B 2009; 114:796-803. [DOI: 10.1021/jp909872a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yanxin Liu
- Department of Physics, Florida International University, University Park, Miami, Florida 33199
| | - Prem P. Chapagain
- Department of Physics, Florida International University, University Park, Miami, Florida 33199
| | - Bernard S. Gerstman
- Department of Physics, Florida International University, University Park, Miami, Florida 33199
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10
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Song Y, Pipalia NH, Fung LWM. The L49F mutation in alpha erythroid spectrin induces local disorder in the tetramer association region: Fluorescence and molecular dynamics studies of free and bound alpha spectrin. Protein Sci 2009; 18:1916-25. [PMID: 19593814 DOI: 10.1002/pro.202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The bundling of the N-terminal, partial domain helix (Helix C') of human erythroid alpha-spectrin (alphaI) with the C-terminal, partial domain helices (Helices A' and B') of erythroid beta-spectrin (betaI) to give a spectrin pseudo structural domain (triple helical bundle A'B'C') has long been recognized as a crucial step in forming functional spectrin tetramers in erythrocytes. We have used apparent polarity and Stern-Volmer quenching constants of Helix C' of alphaI bound to Helices A' and B' of betaI, along with previous NMR and EPR results, to propose a model for the triple helical bundle. This model was used as the input structure for molecular dynamics simulations for both wild type (WT) and alphaI mutant L49F. The simulation output structures show a stable helical bundle for WT, but not for L49F. In WT, four critical interactions were identified: two hydrophobic clusters and two salt bridges. However, in L49F, the region downstream of Helix C' was unable to assume a helical conformation and one critical hydrophobic cluster was disrupted. Other molecular interactions critical to the WT helical bundle were also weakened in L49F, possibly leading to the lower tetramer levels observed in patients with this mutation-induced blood disorder.
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Affiliation(s)
- Yuanli Song
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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Abstract
Although the energetic balance of forces stabilizing proteins has been established qualitatively over the last decades, quantification of the energetic contribution of particular interactions still poses serious problems. The reasons are the strong cooperativity and the interdependence ofnoncovalent interactions. Salt bridges are a typical example. One expects that ionizable side chains frequently form ion pairs in innumerable crystal structures. Since electrostatic attraction between opposite charges is strong per se, salt bridges can intuitively be regarded as an important factor stabilizing the native structure. Is that really so? In this chapter we critically reassess the available methods to delineate the role ofelectrostatic interactions and salt bridges to protein stability, and discuss the progress and the obstacles in this endeavor. The basic problem is that formation of salt bridges depends on the ionization properties of the participating groups, which is significantly influenced by the protein environment. Furthermore, salt bridges experience thermal fluctuations, continuously break and re-form, and their lifespan in solution is governed by the flexibility of the protein. Finally, electrostatic interactions are long-range and might be significant in the unfolded state, thus seriously influencing the energetic profile. Elimination of salt bridges by protonation/deprotonation at extreme pH or by mutation provides only rough energetic estimates, since there is no way to account for the nonadditive response of the protein moiety. From what we know so far, the strength of electrostatic interactions is strongly context-dependent, yet it is unlikely that salt bridges are dominant factors governing protein stability. Nevertheless, proteins from thermophiles and hyperthermophiles exhibit more, and frequently networked, salt bridges than proteins from the mesophilic counterparts. Increasing the thermal (not the thermodynamic) stability of proteins by optimization of charge-charge interactions is a good example for an evolutionary solution utilizing physical factors.
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Affiliation(s)
- Ilian Jelesarov
- Biochemisches Institut der Universität Zürich, Zürich, Switzerland
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