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Beygmoradi A, Homaei A, Hemmati R, Fernandes P. Recombinant protein expression: Challenges in production and folding related matters. Int J Biol Macromol 2023; 233:123407. [PMID: 36708896 DOI: 10.1016/j.ijbiomac.2023.123407] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/13/2023] [Accepted: 01/20/2023] [Indexed: 01/26/2023]
Abstract
Protein folding is a biophysical process by which proteins reach a specific three-dimensional structure. The amino acid sequence of a polypeptide chain contains all the information needed to determine the final three-dimensional structure of a protein. When producing a recombinant protein, several problems can occur, including proteolysis, incorrect folding, formation of inclusion bodies, or protein aggregation, whereby the protein loses its natural structure. To overcome such limitations, several strategies have been developed to address each specific issue. Identification of proper protein refolding conditions can be challenging, and to tackle this high throughput screening for different recombinant protein folding conditions can prove a sound solution. Different approaches have emerged to tackle refolding issues. One particular approach to address folding issues involves molecular chaperones, highly conserved proteins that contribute to proper folding by shielding folding proteins from other proteins that could hinder the process. Proper protein folding is one of the main prerequisites for post-translational modifications. Incorrect folding, if not dealt with, can lead to a buildup of protein misfoldings that damage cells and cause widespread abnormalities. Said post-translational modifications, widespread in eukaryotes, are critical for protein structure, function and biological activity. Incorrect post-translational protein modifications may lead to individual consequences or aggregation of therapeutic proteins. In this review article, we have tried to examine some key aspects of recombinant protein expression. Accordingly, the relevance of these proteins is highlighted, major problems related to the production of recombinant protein and to refolding issues are pinpointed and suggested solutions are presented. An overview of post-translational modification, their biological significance and methods of identification are also provided. Overall, the work is expected to illustrate challenges in recombinant protein expression.
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Affiliation(s)
- Azadeh Beygmoradi
- Department of Marine Biology, Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran
| | - Ahmad Homaei
- Department of Marine Biology, Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran.
| | - Roohullah Hemmati
- Department of Biology, Faculty of Basic Sciences, Shahrekord University, Shahrekord, Iran
| | - Pedro Fernandes
- DREAMS and Faculdade de Engenharia, Universidade Lusófona de Humanidades e Tecnologias, Av. Campo Grande 376, 1749-024 Lisboa, Portugal; iBB-Institute for Bioengineering and Biosciences and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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2
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Carman PJ, Dominguez R. Novel Protein Production Method Combining Native Expression in Human Cells with an Intein-based Affinity Purification and Self-cleavable Tag. Bio Protoc 2022; 12:e4363. [PMID: 35434194 PMCID: PMC8983157 DOI: 10.21769/bioprotoc.4363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 12/03/2021] [Accepted: 02/09/2022] [Indexed: 12/29/2022] Open
Abstract
The human proteins used in most biochemical studies are commonly obtained using bacterial expression. Owing to its relative simplicity and low cost, this approach has been extremely successful, but is inadequate for many proteins that require the mammalian folding machinery and posttranslational modifications (PTMs) for function. Moreover, the expressed proteins are typically purified using N- and/or C-terminal affinity tags, which are often left on proteins or leave non-native extra amino acids when removed proteolytically. Many proteins cannot tolerate such extra amino acids for function. Here we describe a protein production method that resolves both these issues. Our method combines expression in human Expi293F cells, which grow in suspension to high density and can process native PTMs, with a chitin-binding domain (CBD)-intein affinity purification and self-cleavable tag, which can be precisely removed after purification. In this protocol, we describe how to clone a target gene into our specifically designed human cell expression vector (pJCX4), and how to efficiently transfect the Expi293F cells and purify the expressed proteins using a chitin affinity resin. Graphic abstract.
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Affiliation(s)
- Peter J. Carman
- Department of Physiology and Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Roberto Dominguez
- Department of Physiology and Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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3
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Sorokina I, Mushegian AR, Koonin EV. Is Protein Folding a Thermodynamically Unfavorable, Active, Energy-Dependent Process? Int J Mol Sci 2022; 23:521. [PMID: 35008947 PMCID: PMC8745595 DOI: 10.3390/ijms23010521] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 02/04/2023] Open
Abstract
The prevailing current view of protein folding is the thermodynamic hypothesis, under which the native folded conformation of a protein corresponds to the global minimum of Gibbs free energy G. We question this concept and show that the empirical evidence behind the thermodynamic hypothesis of folding is far from strong. Furthermore, physical theory-based approaches to the prediction of protein folds and their folding pathways so far have invariably failed except for some very small proteins, despite decades of intensive theory development and the enormous increase of computer power. The recent spectacular successes in protein structure prediction owe to evolutionary modeling of amino acid sequence substitutions enhanced by deep learning methods, but even these breakthroughs provide no information on the protein folding mechanisms and pathways. We discuss an alternative view of protein folding, under which the native state of most proteins does not occupy the global free energy minimum, but rather, a local minimum on a fluctuating free energy landscape. We further argue that ΔG of folding is likely to be positive for the majority of proteins, which therefore fold into their native conformations only through interactions with the energy-dependent molecular machinery of living cells, in particular, the translation system and chaperones. Accordingly, protein folding should be modeled as it occurs in vivo, that is, as a non-equilibrium, active, energy-dependent process.
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Affiliation(s)
| | - Arcady R. Mushegian
- Division of Molecular and Cellular Biosciences, National Science Foundation, Alexandria, VA 22314, USA;
- Clare Hall College, University of Cambridge, Cambridge CB3 9AL, UK
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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4
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Functional expression of an echinocandin B deacylase from Actinoplanes utahensis in Escherichia coli. Int J Biol Macromol 2021; 187:850-857. [PMID: 34339787 DOI: 10.1016/j.ijbiomac.2021.07.146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 07/10/2021] [Accepted: 07/21/2021] [Indexed: 11/20/2022]
Abstract
Echinocandin B deacylase (ECBD) from Actinoplanes utahensis can be applied to produce echinocandin B nucleus (ECBN), an essential intermediate of the echinocandins antifungal drugs such as anidulafungin. To date, the expression of ECBD has been limited to Streptomyces. To achieve the active expression of ECBD in Escherichia coli (E. coli), we constructed a plasmid carrying two subunits of ECBD for T7 RNA polymerase driven transcription of dicistron messenger after codon optimization. Subsequently, the introduction of peptide tags in the recombinant ECBD was adopted to reduce the formation of inclusion bodies and enhance the ECBD solubility. The peptide tags with the opposite electrostatic charge, hexa-lysine (6K) and GEGEG (GE), exhibited the best positive effect, which was verified by activity assay and structural simulation. After that, optimization of culture conditions and characterization of ECBD were conducted, the optimal pH and temperature were 7.0 and 60 °C. It is the first report concerning the functional expression of ECBD in the host E. coli. Our results reported here can provide a reference for the high-level expression of other deacylases with respect to a possible industrial application.
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Sanagavarapu K, Nüske E, Nasir I, Meisl G, Immink JN, Sormanni P, Vendruscolo M, Knowles TPJ, Malmendal A, Cabaleiro-Lago C, Linse S. A method of predicting the in vitro fibril formation propensity of Aβ40 mutants based on their inclusion body levels in E. coli. Sci Rep 2019; 9:3680. [PMID: 30842594 PMCID: PMC6403284 DOI: 10.1038/s41598-019-39216-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 12/12/2018] [Indexed: 12/12/2022] Open
Abstract
Overexpression of recombinant proteins in bacteria may lead to their aggregation and deposition in inclusion bodies. Since the conformational properties of proteins in inclusion bodies exhibit many of the characteristics typical of amyloid fibrils. Based on these findings, we hypothesize that the rate at which proteins form amyloid fibrils may be predicted from their propensity to form inclusion bodies. To establish a method based on this concept, we first measured by SDS-PAGE and confocal microscopy the level of inclusion bodies in E. coli cells overexpressing the 40-residue amyloid-beta peptide, Aβ40, wild-type and 24 charge mutants. We then compared these results with a number of existing computational aggregation propensity predictors as well as the rates of aggregation measured in vitro for selected mutants. Our results show a strong correlation between the level of inclusion body formation and aggregation propensity, thus demonstrating the power of this approach and its value in identifying factors modulating aggregation kinetics.
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Affiliation(s)
- Kalyani Sanagavarapu
- Lund University, Biochemistry and Structural Biology, Chemical Center, Lund, Sweden.
| | | | - Irem Nasir
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 N, Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Georg Meisl
- University of Cambridge, Chemistry Department, Lensfield Road, Cambridge, UK
| | - Jasper N Immink
- Lund University, Physical Chemistry, Chemical Center, Lund, Sweden
| | - Pietro Sormanni
- University of Cambridge, Chemistry Department, Lensfield Road, Cambridge, UK
| | - Michele Vendruscolo
- University of Cambridge, Chemistry Department, Lensfield Road, Cambridge, UK
| | - Tuomas P J Knowles
- University of Cambridge, Chemistry Department, Lensfield Road, Cambridge, UK.,Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge, UK
| | - Anders Malmendal
- Lund University, Biochemistry and Structural Biology, Chemical Center, Lund, Sweden
| | - Celia Cabaleiro-Lago
- Lund University, Biochemistry and Structural Biology, Chemical Center, Lund, Sweden.,Faculty of natural sciences, Kristianstad University, Kristianstad, Sweden
| | - Sara Linse
- Lund University, Biochemistry and Structural Biology, Chemical Center, Lund, Sweden.
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Paraskevopoulou V, Falcone FH. Polyionic Tags as Enhancers of Protein Solubility in Recombinant Protein Expression. Microorganisms 2018; 6:microorganisms6020047. [PMID: 29882886 PMCID: PMC6027335 DOI: 10.3390/microorganisms6020047] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/16/2018] [Accepted: 05/21/2018] [Indexed: 12/30/2022] Open
Abstract
Since the introduction of recombinant protein expression in the second half of the 1970s, the growth of the biopharmaceutical field has been rapid and protein therapeutics has come to the foreground. Biophysical and structural characterisation of recombinant proteins is the essential prerequisite for their successful development and commercialisation as therapeutics. Despite the challenges, including low protein solubility and inclusion body formation, prokaryotic host systems and particularly Escherichia coli, remain the system of choice for the initial attempt of production of previously unexpressed proteins. Several different approaches have been adopted, including optimisation of growth conditions, expression in the periplasmic space of the bacterial host or co-expression of molecular chaperones, to assist correct protein folding. A very commonly employed approach is also the use of protein fusion tags that enhance protein solubility. Here, a range of experimentally tested peptide tags, which present specific advantages compared to protein fusion tags and the concluding remarks of these experiments are reviewed. Finally, a concept to design solubility-enhancing peptide tags based on a protein’s pI is suggested.
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Affiliation(s)
- Vasiliki Paraskevopoulou
- Division of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK.
| | - Franco H Falcone
- Division of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK.
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7
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Slomka C, Späth GP, Lemke P, Skoupi M, Niemeyer CM, Syldatk C, Rudat J. Toward a cell-free hydantoinase process: screening for expression optimization and one-step purification as well as immobilization of hydantoinase and carbamoylase. AMB Express 2017; 7:122. [PMID: 28605882 PMCID: PMC5466576 DOI: 10.1186/s13568-017-0420-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 06/01/2017] [Indexed: 11/13/2022] Open
Abstract
The hydantoinase process is applied for the industrial synthesis of optically pure amino acids via whole cell biocatalysis, providing a simple and well-established method to obtain the catalyst. Nevertheless, whole cell approaches also bear disadvantages like intracellular degradation reactions, transport limitations as well as low substrate solubility. In this work the hydantoinase and carbamoylase from Arthrobacter crystallopoietes DSM 20117 were investigated with respect to their applicability in a cell-free hydantoinase process. Both enzymes were heterologously expressed in Escherichia coli BL21DE3. Cultivation and induction of the hydantoinase under oxygen deficiency resulted in markedly higher specific activities and a further increase in expression was achieved by codon-optimization. Further expression conditions of the hydantoinase were tested using the microbioreactor system BioLector®, which showed a positive effect upon the addition of 3% ethanol to the cultivation medium. Additionally, the hydantoinase and carbamoylase were successfully purified by immobilized metal ion affinity using Ni Sepharose beads as well as by functionalized magnetic beads, while the latter method was clearly more effective with respect to recovery and purification factor. Immobilization of both enzymes via functionalized magnetic beads directly from the crude cell extract was successful and resulted in specific activities that turned out to be much higher than those of the purified free enzymes.
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Ng IS, Chi X, Wu X, Bao Z, Lu Y, Chang JS, Ling X. Cloning and expression of Cel8A from Klebsiella pneumoniae in Escherichia coli and comparison to cel gene of Cellulomonas uda. Biochem Eng J 2013. [DOI: 10.1016/j.bej.2013.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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9
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Abstract
Kinetic data measured from folding of the protein interleukin-1β fits best to three exponential phases when studied with tryptophan fluorescence but only two exponential phases when measured using other methods. The technique of ANS fluorescence was used to determine whether the additional phase observed in tryptophan fluorescence was also detected with ANS dye binding. Unlike trytophan fluorescence, the ANS fluorescence was highly dependent on the concentration of protein present during the folding experiment. Experimental controls provide evidence that ANS binds to protein aggregates, present at higher concentrations and absent at lower concentrations. Protein concentration-dependent folding studies demonstrate that, at lower interleukin-1β concentrations, tryptophan fluorescence kinetics can be fit adequately with a two exponential fit. This study indicates that (1) measured interleukin-1β folding kinetics fit to a 2 phase model and (2) at higher protein concentrations, transient association of IL-1β may result in a kinetic fit of 3 phases.
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Affiliation(s)
- J M Finke
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093-0359
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10
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Abstract
Recombinant production has become an invaluable tool for supplying research and therapy with proteins of interest. The target proteins are not in every case soluble and/or correctly folded. That is why different production parameters such as host, cultivation conditions and co-expression of chaperones and foldases are applied in order to yield functional recombinant protein. There has been a constant increase and success in the use of folding promoting agents in recombinant protein production. Recent cases are reviewed and discussed in this chapter. Any impact of such strategies cannot be predicted and has to be analyzed and optimized for the corresponding target protein. The in vivo effects of the agents are at least partially comparable to their in vitro mode of action and have been studied by means of modern systems approaches and even in combination with folding/activity screening assays. Resulting data can be used directly for experimental planning or can be fed into knowledge-based modelling. An overview of such technologies is included in the chapter in order to facilitate a decision about the potential in vivo use of folding promoting agents.
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Affiliation(s)
- Beatrix Fahnert
- Cardiff School of Biosciences, Cardiff University, Wales, UK.
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11
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Baumann K, Carnicer M, Dragosits M, Graf AB, Stadlmann J, Jouhten P, Maaheimo H, Gasser B, Albiol J, Mattanovich D, Ferrer P. A multi-level study of recombinant Pichia pastoris in different oxygen conditions. BMC SYSTEMS BIOLOGY 2010; 4:141. [PMID: 20969759 PMCID: PMC2987880 DOI: 10.1186/1752-0509-4-141] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 10/22/2010] [Indexed: 12/24/2022]
Abstract
Background Yeasts are attractive expression platforms for many recombinant proteins, and there is evidence for an important interrelation between the protein secretion machinery and environmental stresses. While adaptive responses to such stresses are extensively studied in Saccharomyces cerevisiae, little is known about their impact on the physiology of Pichia pastoris. We have recently reported a beneficial effect of hypoxia on recombinant Fab secretion in P. pastoris chemostat cultivations. As a consequence, a systems biology approach was used to comprehensively identify cellular adaptations to low oxygen availability and the additional burden of protein production. Gene expression profiling was combined with proteomic analyses and the 13C isotope labelling based experimental determination of metabolic fluxes in the central carbon metabolism. Results The physiological adaptation of P. pastoris to hypoxia showed distinct traits in relation to the model yeast S. cerevisiae. There was a positive correlation between the transcriptomic, proteomic and metabolic fluxes adaptation of P. pastoris core metabolism to hypoxia, yielding clear evidence of a strong transcriptional regulation component of key pathways such as glycolysis, pentose phosphate pathway and TCA cycle. In addition, the adaptation to reduced oxygen revealed important changes in lipid metabolism, stress responses, as well as protein folding and trafficking. Conclusions This systems level study helped to understand the physiological adaptations of cellular mechanisms to low oxygen availability in a recombinant P. pastoris strain. Remarkably, the integration of data from three different levels allowed for the identification of differences in the regulation of the core metabolism between P. pastoris and S. cerevisiae. Detailed comparative analysis of the transcriptomic data also led to new insights into the gene expression profiles of several cellular processes that are not only susceptible to low oxygen concentrations, but might also contribute to enhanced protein secretion.
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Affiliation(s)
- Kristin Baumann
- Department of Chemical Engineering, Autonomous University of Barcelona, Spain
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Shen VK, Cheung JK, Errington JR, Truskett TM. Insights Into Crowding Effects on Protein Stability From a Coarse-Grained Model. J Biomech Eng 2009; 131:071002. [DOI: 10.1115/1.3127259] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Proteins aggregate and precipitate from high concentration solutions in a wide variety of problems of natural and technological interest. Consequently, there is a broad interest in developing new ways to model the thermodynamic and kinetic aspects of protein stability in these crowded cellular or solution environments. We use a coarse-grained modeling approach to study the effects of different crowding agents on the conformational equilibria of proteins and the thermodynamic phase behavior of their solutions. At low to moderate protein concentrations, we find that crowding species can either stabilize or destabilize the native state, depending on the strength of their attractive interaction with the proteins. At high protein concentrations, crowders tend to stabilize the native state due to excluded volume effects, irrespective of the strength of the crowder-protein attraction. Crowding agents reduce the tendency of protein solutions to undergo a liquid-liquid phase separation driven by strong protein-protein attractions. The aforementioned equilibrium trends represent, to our knowledge, the first simulation predictions for how the properties of crowding species impact the global thermodynamic stability of proteins and their solutions.
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Affiliation(s)
- Vincent K. Shen
- Physical and Chemical Properties Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8380
| | - Jason K. Cheung
- Biological and Sterile Product Development, Schering-Plough Research Institute, Summit, NJ 07091
| | - Jeffrey R. Errington
- Department of Chemical and Biological Engineering, The State University of New York at Buffalo, Buffalo, NY 14260-4200
| | - Thomas M. Truskett
- Department of Chemical Engineering, and Institute for Theoretical Chemistry, The University of Texas at Austin, Austin, TX 78712
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Zhang L, Lu D, Liu Z. Dynamic control of protein conformation transition in chromatographic separation based on hydrophobic interactions. J Chromatogr A 2009; 1216:2483-90. [DOI: 10.1016/j.chroma.2009.01.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 01/07/2009] [Accepted: 01/12/2009] [Indexed: 11/27/2022]
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Margreiter G, Schwanninger M, Bayer K, Obinger C. Impact of different cultivation and induction regimes on the structure of cytosolic inclusion bodies of TEM1-beta-lactamase. Biotechnol J 2009; 3:1245-55. [PMID: 18702088 DOI: 10.1002/biot.200800072] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The enzyme TEM1-beta-lactamase has been used as a model to study the impact of different cultivation and induction regimes on the structure of cytosolic inclusion bodies (IBs). The protein has been heterologously expressed in Escherichia coli in fed-batch cultivations at different temperatures (30, 37, and 40 degrees C) as well as induction regimes that guaranteed distinct product formation rates and ratios of soluble to aggregated protein. Additionally, shake flask cultivations at 20, 30, and 37 degrees C were performed. IBs were sampled during the whole bioprocess and structural analysis was performed by attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy. This work clearly demonstrates that the tested production regimes and rates had no impact on the IB structure, which was characterized by decreased alpha-helical and increased and modified beta-sheet contents compared to the native protein. Moreover, aggregates formed during refolding of IBs by solubilization and simple dilution showed very similar FT-IR spectra suggesting (i) the existence of only one critical folding step from which either aggregation (IB formation) or native folding branches off, and (ii) underlining the important role of the specific amino acid sequence in aggregation. The findings are discussed with respect to the known structure of TEM1-beta-lactamase and the reported kinetics of its (un)folding as well as contradictory data on the effect of cultivation regimes on IB structure(s) of other proteins.
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Affiliation(s)
- Gerd Margreiter
- Department of Biotechnology Division of Biochemistry, BOKU-University of Natural Resources and Applied Life Sciences, Vienna, Vienna, Austria
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15
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Bershtein S, Goldin K, Tawfik DS. Intense neutral drifts yield robust and evolvable consensus proteins. J Mol Biol 2008; 379:1029-44. [PMID: 18495157 DOI: 10.1016/j.jmb.2008.04.024] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Revised: 04/08/2008] [Accepted: 04/09/2008] [Indexed: 11/27/2022]
Abstract
What changes occur when a natural protein that had been under low mutation rates is subjected to a neutral drift at high mutational loads, thus generating genetically diverse (polymorphic) gene ensembles that all maintain the protein's original function and structure? To address this question we subjected large populations of TEM-1 beta-lactamase to a prolonged neutral drift, applying high mutation rates and purifying selection to maintain TEM-1's existing penicillinase activity. Purging of deleterious mutations and enrichment of beneficial ones maintained the sequence of these ensembles closer to TEM-1's family consensus and inferred ancestor. In particular, back-to-consensus/ancestor mutations that increase TEM-1's kinetic and thermodynamic stability were enriched. These acted as global suppressors and enabled the tolerance of a broad range of deleterious mutations, thus further increasing the genetic diversity of the drifting populations. The probability of a new function emerging (cefotaxime degradation) was also substantially increased in these ensembles owing to the presence of many gene variants carrying the global suppressors. Our findings indicate the unique features of large, polymorphic neutral ensembles generated under high mutational loads and prompt the speculation that the progenitors of today's proteins may have evolved under high mutational loads. The results also suggest that predictable back-to-consensus/ancestor changes can be used in the laboratory to generate highly diverse and evolvable gene libraries.
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Affiliation(s)
- Shimon Bershtein
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, 76100, Israel
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16
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Zhang L, Lu D, Liu Z. How native proteins aggregate in solution: A dynamic Monte Carlo simulation. Biophys Chem 2008; 133:71-80. [DOI: 10.1016/j.bpc.2007.12.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 12/16/2007] [Accepted: 12/16/2007] [Indexed: 11/15/2022]
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17
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trans-Cyclohexanediamines Prevent Thermal Inactivation of Protein: Role of Hydrophobic and Electrostatic Interactions. Protein J 2008; 27:253-7. [DOI: 10.1007/s10930-008-9132-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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18
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Kar K, Kishore N. Enhancement of thermal stability and inhibition of protein aggregation by osmolytic effect of hydroxyproline. Biopolymers 2007; 87:339-51. [PMID: 17764077 DOI: 10.1002/bip.20834] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A combination of spectroscopic, calorimetric, and microscopic studies to understand the effect of hydroxyproline on the thermal stability, conformation, biological activity, and aggregation of proteins has been investigated. Significantly increased protein stability and suppression of aggregation is achieved in the presence of hydroxyproline. For example, exceptional increase in the thermal stability of lysozyme up to 26.4 degrees C and myoglobin up to 31.8 degrees C is obtained in the presence of hydroxyproline. The increased thermal stability of the proteins is observed to be accompanied with significant rise of the catalytic activity. Hydroxyproline is observed to prevent lysozyme fibril formation in vitro. Fluorescence and circular dichroism studies indicate induction of tertiary structures of the studied proteins in the presence of hydroxyproline. Preferential hydration of the native state is found to be crucial for the mechanism of protein stabilization by hydroxyproline. We compared the effect of hydroxyproline to that of proline and observed similar increase in the activity and suppression of protein aggregation. The results demonstrate the use of hydroxyproline as a protein stabilizer and in the prevention of protein aggregation and fibril formation.
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Affiliation(s)
- Karunakar Kar
- Indian Institute of Technology-Bombay, Powai, Mumbai, India
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19
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Possoz C, Newmark J, Sorto N, Sherratt DJ, Tolmasky ME. Sublethal concentrations of the aminoglycoside amikacin interfere with cell division without affecting chromosome dynamics. Antimicrob Agents Chemother 2006; 51:252-6. [PMID: 17043119 PMCID: PMC1797645 DOI: 10.1128/aac.00892-06] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aminoglycosides bind to the 16S rRNA at the tRNA acceptor site (A site) and disturb protein synthesis by inducing codon misreading. We investigated Escherichia coli cell elongation and division, as well as the dynamics of chromosome replication and segregation, in the presence of sublethal concentrations of amikacin (AMK). The fates of the chromosome ori and ter loci were monitored by visualization by using derivatives of LacI and TetR fused to fluorescent proteins in E. coli strains that carry operator arrays at the appropriate locations. The results showed that cultures containing sublethal concentrations of AMK contained abnormally elongated cells. The chromosomes in these cells were properly located, suggesting that the dynamics of replication and segregation were normal. FtsZ, an essential protein in the process of cell division, was studied by using an ectopic FtsZ-cyan fluorescent protein fusion. Consistent with a defect in cell division, we revealed that the Z ring failed to properly assemble in these elongated cells.
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Affiliation(s)
- Christophe Possoz
- College of Natural Science and Mathematics, P.O. Box 6850, 800 N. State College Boulevard, Fullerton, CA 92831-3599, USA
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Bomhoff G, Sloan K, McLain C, Gogol EP, Fisher MT. The effects of the flavonoid baicalein and osmolytes on the Mg 2+ accelerated aggregation/fibrillation of carboxymethylated bovine 1SS-α-lactalbumin. Arch Biochem Biophys 2006; 453:75-86. [PMID: 16530158 DOI: 10.1016/j.abb.2006.02.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 02/02/2006] [Indexed: 12/01/2022]
Abstract
Many protein conformational diseases arise when proteins form alternative stable conformations, resulting in aggregation and accumulation of the protein as fibrillar deposits, or amyloids. Interestingly, numerous proteins implicated in amyloid protein formation show similar structural and functional properties. Given this similarity, we tested the notion that carboxymethylated bovine alpha-lactalbumin (1SS-alpha-lac) could serve as a general amyloid fibrillation/aggregation model system. Like most amyloid forming systems, Mg2+ ions accelerate 1SS-alpha-lac amyloid fibril formation. While osmolytes such as trimethylamine N-oxide (TMAO), and sucrose enhanced thioflavin T detected aggregation, a mixture of trehalose and TMAO substantially inhibited aggregation. Most importantly however, the flavonoid, baicalein, known to inhibit alpha-synuclein amyloid fibril formation, also inhibits 1SS-alpha-lac amyloid with the same apparent efficacy. These data suggest that the easily obtainable 1SS-alpha-lac protein can serve as a general amyloid model and that some small molecule amyloid inhibitors may function successfully with many different amyloid systems.
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Affiliation(s)
- Greg Bomhoff
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
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21
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Weinreich DM, Delaney NF, Depristo MA, Hartl DL. Darwinian evolution can follow only very few mutational paths to fitter proteins. Science 2006; 312:111-4. [PMID: 16601193 DOI: 10.1126/science.1123539] [Citation(s) in RCA: 950] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Five point mutations in a particular beta-lactamase allele jointly increase bacterial resistance to a clinically important antibiotic by a factor of approximately 100,000. In principle, evolution to this high-resistance beta-lactamase might follow any of the 120 mutational trajectories linking these alleles. However, we demonstrate that 102 trajectories are inaccessible to Darwinian selection and that many of the remaining trajectories have negligible probabilities of realization, because four of these five mutations fail to increase drug resistance in some combinations. Pervasive biophysical pleiotropy within the beta-lactamase seems to be responsible, and because such pleiotropy appears to be a general property of missense mutations, we conclude that much protein evolution will be similarly constrained. This implies that the protein tape of life may be largely reproducible and even predictable.
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Affiliation(s)
- Daniel M Weinreich
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
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22
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Ventura S, Villaverde A. Protein quality in bacterial inclusion bodies. Trends Biotechnol 2006; 24:179-85. [PMID: 16503059 DOI: 10.1016/j.tibtech.2006.02.007] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Accepted: 02/13/2006] [Indexed: 11/29/2022]
Abstract
A common limitation of recombinant protein production in bacteria is the formation of insoluble protein aggregates known as inclusion bodies. The propensity of a given protein to aggregate is unpredictable, and the goal of a properly folded, soluble species has been pursued using four main approaches: modification of the protein sequence; increasing the availability of folding assistant proteins; increasing the performance of the translation machinery; and minimizing physicochemical conditions favoring conformational stress and aggregation. From a molecular point of view, inclusion bodies are considered to be formed by unspecific hydrophobic interactions between disorderly deposited polypeptides, and are observed as "molecular dust-balls" in productive cells. However, recent data suggest that these protein aggregates might be a reservoir of alternative conformational states, their formation being no less specific than the acquisition of the native-state structure.
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Affiliation(s)
- Salvador Ventura
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
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23
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Shen VK, Cheung JK, Errington JR, Truskett TM. Coarse-grained strategy for modeling protein stability in concentrated solutions. II: phase behavior. Biophys J 2006; 90:1949-60. [PMID: 16387768 PMCID: PMC1386775 DOI: 10.1529/biophysj.105.076497] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Accepted: 12/08/2005] [Indexed: 11/18/2022] Open
Abstract
We use highly efficient transition-matrix Monte Carlo simulations to determine equilibrium unfolding curves and fluid phase boundaries for solutions of coarse-grained globular proteins. The model we analyze derives the intrinsic stability of the native state and protein-protein interactions from basic information about protein sequence using heteropolymer collapse theory. It predicts that solutions of low hydrophobicity proteins generally exhibit a single liquid phase near their midpoint temperatures for unfolding, while solutions of proteins with high sequence hydrophobicity display the type of temperature-inverted, liquid-liquid transition associated with aggregation processes of proteins and other amphiphilic molecules. The phase transition occurring in solutions of the most hydrophobic protein we study extends below the unfolding curve, creating an immiscibility gap between a dilute, mostly native phase and a concentrated, mostly denatured phase. The results are qualitatively consistent with the solution behavior of hemoglobin (HbA) and its sickle variant (HbS), and they suggest that a liquid-liquid transition resulting in significant protein denaturation should generally be expected on the phase diagram of high-hydrophobicity protein solutions. The concentration fluctuations associated with this transition could be a driving force for the nonnative aggregation that can occur below the midpoint temperature.
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Affiliation(s)
- Vincent K Shen
- Physical and Chemical Properties Division, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
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24
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DePristo MA, Weinreich DM, Hartl DL. Missense meanderings in sequence space: a biophysical view of protein evolution. Nat Rev Genet 2006; 6:678-87. [PMID: 16074985 DOI: 10.1038/nrg1672] [Citation(s) in RCA: 484] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Proteins are finicky molecules; they are barely stable and are prone to aggregate, but they must function in a crowded environment that is full of degradative enzymes bent on their destruction. It is no surprise that many common diseases are due to missense mutations that affect protein stability and aggregation. Here we review the literature on biophysics as it relates to molecular evolution, focusing on how protein stability and aggregation affect organismal fitness. We then advance a biophysical model of protein evolution that helps us to understand phenomena that range from the dynamics of molecular adaptation to the clock-like rate of protein evolution.
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Affiliation(s)
- Mark A DePristo
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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25
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Maestro B, Sanz J. Accumulation of partly folded states in the equilibrium unfolding of the pneumococcal choline-binding module C-LytA. Biochem J 2005; 387:479-88. [PMID: 15574122 PMCID: PMC1134977 DOI: 10.1042/bj20041194] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Choline-binding modules are present in some virulence factors and many other proteins of Streptococcus pneumoniae (Pneumococcus). The most extensively studied choline-binding module is C-LytA, the C-terminal moiety of the pneumococcal cell-wall amidase LytA. The three-dimensional structure of C-LytA is built up from six loop-hairpin structures forming a left-handed beta-solenoid with four choline-binding sites. The affinity of C-LytA for choline and other structural analogues allows its use as an efficient fusion tag for single-step purification of hybrid proteins. In the present study, we characterize the folding and stability of C-LytA by chemical and thermal equilibrium denaturation experiments. Unfolding experiments using guanidinium chloride at pH 7.0 and 20 degrees C suggest the existence of two partly folded states (I1 and I2) in the following model: N (native)-->I1<=>I2. The N-->I1 transition is non-co-operative and irreversible, and is significant even in the absence of a denaturant. In contrast, the I1<=>I2 transition is co-operative and reversible, with an associated freeenergy change (DeltaG(0)) of 30.9+/-0.8 kJ x mol(-1). The residual structure in the I2 state is unusually stable even in 7.4 M guanidinium chloride. Binding of choline stabilizes the structure of the native state, induces its dimerization and prevents the accumulation of the I1 species ([N]2<=>[I2]2, DeltaG(0)=50.1+/-0.8 kJ x mol(-1)). Fluorescence and CD measurements, gel-filtration chromatography and limited proteolysis suggest that I1 differs from N in the local unfolding of the N-terminal beta-hairpins, and that I2 has a residual structure in the C-terminal region. Thermal denaturation of C-LytA suggests the accumulation of at least the I1 species. These results might pave the way for an effective improvement of its biotechnological applications by protein engineering.
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Affiliation(s)
- Beatriz Maestro
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Av. Universidad, s/n, E-03202 Elche (Alicante), Spain
| | - Jesús M. Sanz
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Av. Universidad, s/n, E-03202 Elche (Alicante), Spain
- To whom correspondence should be addressed (email )
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Ventura S. Sequence determinants of protein aggregation: tools to increase protein solubility. Microb Cell Fact 2005; 4:11. [PMID: 15847694 PMCID: PMC1087874 DOI: 10.1186/1475-2859-4-11] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Accepted: 04/22/2005] [Indexed: 11/10/2022] Open
Abstract
Escherichia coli is one of the most widely used hosts for the production of recombinant proteins. However, very often the target protein accumulates into insoluble aggregates in a misfolded and biologically inactive form. Bacterial inclusion bodies are major bottlenecks in protein production and are hampering the development of top priority research areas such structural genomics. Inclusion body formation was formerly considered to occur via non-specific association of hydrophobic surfaces in folding intermediates. Increasing evidence, however, indicates that protein aggregation in bacteria resembles to the well-studied process of amyloid fibril formation. Both processes appear to rely on the formation of specific, sequence-dependent, intermolecular interactions driving the formation of structured protein aggregates. This similarity in the mechanisms of aggregation will probably allow applying anti-aggregational strategies already tested in the amyloid context to the less explored area of protein aggregation inside bacteria. Specifically, new sequence-based approaches appear as promising tools to tune protein aggregation in biotechnological processes.
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Affiliation(s)
- Salvador Ventura
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain.
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27
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Wang W. Protein aggregation and its inhibition in biopharmaceutics. Int J Pharm 2005; 289:1-30. [PMID: 15652195 DOI: 10.1016/j.ijpharm.2004.11.014] [Citation(s) in RCA: 687] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2004] [Revised: 08/20/2004] [Accepted: 11/12/2004] [Indexed: 12/21/2022]
Abstract
Protein aggregation is arguably the most common and troubling manifestation of protein instability, encountered in almost all stages of protein drug development. Protein aggregation, along with other physical and/or chemical instabilities of proteins, remains to be one of the major road barriers hindering rapid commercialization of potential protein drug candidates. Although a variety of methods have been used/designed to prevent/inhibit protein aggregation, the end results are often unsatisfactory for many proteins. The limited success is partly due to our lack of a clear understanding of the protein aggregation process. This article intends to discuss protein aggregation and its related mechanisms, methods characterizing protein aggregation, factors affecting protein aggregation, and possible venues in aggregation prevention/inhibition in various stages of protein drug development.
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Affiliation(s)
- Wei Wang
- Biotechnology Division, Bayer HealthCare, 800 Dwight Way, Berkeley, CA 94701, USA.
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Kendrick BS, Li T, Chang BS. Physical stabilization of proteins in aqueous solution. PHARMACEUTICAL BIOTECHNOLOGY 2002; 13:61-84. [PMID: 11987754 DOI: 10.1007/978-1-4615-0557-0_3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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30
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Shin I, Wachtel E, Roth E, Bon C, Silman I, Weiner L. Thermal denaturation of Bungarus fasciatus acetylcholinesterase: Is aggregation a driving force in protein unfolding? Protein Sci 2002; 11:2022-32. [PMID: 12142456 PMCID: PMC2373691 DOI: 10.1110/ps.0205102] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A monomeric form of acetylcholinesterase from the venom of Bungarus fasciatus is converted to a partially unfolded molten globule species by thermal inactivation, and subsequently aggregates rapidly. To separate the kinetics of unfolding from those of aggregation, single molecules of the monomeric enzyme were encapsulated in reverse micelles of Brij 30 in 2,2,4-trimethylpentane, or in large unilamellar vesicles of egg lecithin/cholesterol at various protein/micelle (vesicle) ratios. The first-order rate constant for thermal inactivation at 45 degrees C, of single molecules entrapped within the reverse micelles (0.031 min(-1)), was higher than in aqueous solution (0.007 min(-1)) or in the presence of normal micelles (0.020 min(-1)). This clearly shows that aggregation does not provide the driving force for thermal inactivation of BfAChE. Within the large unilamellar vesicles, at average protein/vesicle ratios of 1:1 and 10:1, the first-order rate constants for thermal inactivation of the encapsulated monomeric acetylcholinesterase, at 53 degrees C, were 0.317 and 0.342 min(-1), respectively. A crosslinking technique, utilizing the photosensitive probe, hypericin, showed that thermal denaturation produces a distribution of species ranging from dimers through to large aggregates. Consequently, at a protein/vesicle ratio of 10:1, aggregation can occur upon thermal denaturation. Thus, these experiments also demonstrate that aggregation does not drive the thermal unfolding of Bungarus fasciatus acetylcholinesterase. Our experimental approach also permitted monitoring of recovery of enzymic activity after thermal denaturation in the absence of a competing aggregation process. Whereas no detectable recovery of enzymic activity could be observed in aqueous solution, up to 23% activity could be obtained for enzyme sequestered in the reverse micelles.
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Affiliation(s)
- I Shin
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
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31
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de la Torre F, García-Gutiérrez A, Crespillo R, Cantón FR, Avila C, Cánovas FM. Functional expression of two pine glutamine synthetase genes in bacteria reveals that they encode cytosolic holoenzymes with different molecular and catalytic properties. PLANT & CELL PHYSIOLOGY 2002; 43:802-809. [PMID: 12154143 DOI: 10.1093/pcp/pcf094] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Two glutamine synthetase isogenes, GS1a and GS1b, isolated from pine have been functionally expressed in E. coli and the characteristics of individual gene products compared. When bacteria were grown at 37 degrees C most pine GS1 protein was found in the insoluble fraction but lowering of the expression temperature increased yield of both GS1 polypeptide and activity in the soluble fraction. High levels of functionally active GS1a (309 + or - 35 nkat mg(-1)) and GS1b (1,166 + or - 65 nkat mg(-1)) enzymes were obtained by decreasing the expression temperature to 10 degrees C. Purification and characterization of recombinant products showed that pine GS1 polypeptides are assembled in octameric GS holoenzymes showing structural and kinetic differences. The results are discussed with regard to the specific localization of GS1a and GS1b in different cell types of pine seedlings. The isoform GS1a may control the assimilation of the high levels of ammonium released in photosynthetic tissues, whereas GS1b enzyme could mitigate oscillations in glutamate availability providing a constant flux of glutamine for nitrogen transport in vascular cells.
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Affiliation(s)
- Fernando de la Torre
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Unidad Asociada UMA-CSIC, Universidad de Málaga, Campus de Teatinos, E-29071 Málaga, Spain
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32
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Webb SD, Cleland JL, Carpenter JF, Randolph TW. A new mechanism for decreasing aggregation of recombinant human interferon-gamma by a surfactant: slowed dissolution of lyophilized formulations in a solution containing 0.03% polysorbate 20. J Pharm Sci 2002; 91:543-58. [PMID: 11835212 DOI: 10.1002/jps.10033] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To study the mechanisms by which Tween 20 (polysorbate 20) used in a reconstitution solution affects the aggregation of lyophilized recombinant human interferon-gamma (rhIFN-gamma), we used four types of buffered formulations containing 0.4-5 mg/mL rhIFN-gamma in either 10 mM potassium phosphate or phosphate buffered saline: (1) without excipients, (2) with 5% sucrose, (3) with 0.03% polysorbate 20, or (4) with the combination of 5% sucrose and 0.03% polysorbate 20. After lyophilization, infrared spectroscopy was used to analyze the secondary structure of the protein in the freeze-dried solid. Each solid showed structural perturbation of the protein. Each formulation was reconstituted with water or a 0.03% polysorbate 20 solution. Aggregation of rhIFN-gamma after reconstitution was measured by optical density at A(350), and recovery of soluble protein was determined by high-performance liquid chromatography and ultraviolet spectroscopy. After reconstitution with a 0.03% polysorbate 20 solution, aggregation levels in all formulations were either reduced or similar to those found after reconstitution with water. These results revealed the potential for recovery of native protein using the appropriate reconstitution conditions, even though the protein is non-native in the lyophilized state. Urea-induced unfolding with and without polysorbate 20 as measured by second-derivative ultraviolet spectroscopy indicated that a concentration of 0.03% polysorbate 20 lowered the free energy of unfolding for rhIFN-gamma (destabilizing). Polysorbate 20 also retarded refolding from urea solutions and increased aggregation. At a level of 0.03%, polysorbate 20 did not protect the protein against surface-induced aggregation during agitation. Dissolution times in water versus a 0.03% polysorbate 20 solution were measured using a rotating disk electrode for lyophilized formulations containing an electrochemically reactive species. The presence of 0.03% polysorbate 20 in the reconstitution solution nearly doubled the time required for dissolution of the phosphate buffered saline formulation, and the sucrose formulations dissolved 33-57% more slowly. Slowing the dissolution rates of lyophilized powders allows more time for the protein to refold while it decreases the maximum concentration of the protein at the dissolution interface, thus reducing the total amount of aggregation.
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Affiliation(s)
- Serena D Webb
- Department of Chemical Engineering, Center for Pharmaceutical Biotechnology, University of Colorado, Engineering Center, Room ECCH 111, Boulder, Colorado 80309-0424, USA
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Lawung R, Prachayasittikul V, Bülow L. Purification and characterization of a beta-lactamase from Haemophilus ducreyi in Escherichia coli. Protein Expr Purif 2001; 23:151-8. [PMID: 11570857 DOI: 10.1006/prep.2001.1485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A pCb plasmid encoding a beta-lactamase from Haemophilus ducreyi was transferred to Escherichia coli, purified, and characterized. The beta-lactamase could be isolated from a culture filtrate and further purified by ammonium sulfate and chelating Sepharose fast flow loaded with Zn(2+). The purified enzyme resulted in a major band at approximately 30-kDa on SDS-PAGE and its pI was determined to be 5.4. The beta-lactamase could hydrolyze both penicillin antibiotics including ampicillin, benzylpenicillin, and carbenicillin as well as cephalosporin antibiotics including nitrocefin, cephalothin, cephaloridine, and cefoperazone. However, benzylpenicillin was the best substrate. The enzyme activity was inhibited by clavulanic acid but not by boric acid, cefotaxime, ethylenediaminetetraacetic acid, or phenylmethylsulfonyl fluoride. The sequence of the beta-lactamase gene was also determined. It confirmed that the enzyme belonged to a class A beta-lactamase which had 99% identity to the ampicillin resistance transposon Tn3 of pBR322. Two nucleotides were different between the E. coli (Tn3) and H. ducreyi (pCb) genes that affected the amino-acid sequence. The valine at position 82 (ABL 84) was changed to isoleucine and the alanine at position 182 (ABL 184) was changed to valine. Genetic homogeneity among beta-lactamases is remarkable. Amino acid sequencing of some beta-lactamases has shown that substitution of only a few amino acids in the bla gene leads to high-level resistance against specific cephalosporins.
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Affiliation(s)
- R Lawung
- Department of Pure and Applied Biochemistry, Center for Chemistry and Chemical Engineering, Lund, S-221 00, Sweden
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Sideraki V, Huang W, Palzkill T, Gilbert HF. A secondary drug resistance mutation of TEM-1 -lactamase that suppresses misfolding and aggregation. Proc Natl Acad Sci U S A 2001; 98:283-8. [PMID: 11114163 PMCID: PMC14582 DOI: 10.1073/pnas.98.1.283] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Gram-negative bacteria, TEM-1 beta-lactamase provides the major mechanism of plasmid-mediated beta-lactam resistance. Natural variants of TEM-1 with increased antibiotic resistance have appeared in response to the use of extended-spectrum beta-lactam antibiotics (e.g., ceftazidime) and beta-lactamase inhibitors (e.g., clavulanic acid). Some of the variant enzymes are more efficient at catalyzing beta-lactam hydrolysis, whereas others are more resistant to inhibitors. M182T is a substitution observed in both types of variant TEM-1 beta-lactamases. This mutation is found only in combination with other amino acid substitutions, suggesting that it may correct defects introduced by other mutations that alter the specificity. An engineered core mutation, L76N, which diminishes the periplasmic beta-lactamase activity by 100-fold, was used as a model to understand the mechanism of suppression of the M182T mutation. Biochemical studies of the L76N enzyme alone and in combination with the M182T mutation indicate that the M182T substitution acts at the level of folding but does not affect the thermodynamic stability of TEM-1 beta-lactamase. Thus, the M182T substitution is an example of a naturally occurring mutation that has evolved to alter the folding pathway of a protein and confer a selective advantage during the evolution of drug resistance.
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Affiliation(s)
- V Sideraki
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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35
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A secondary drug resistance mutation of TEM-1 beta-lactamase that suppresses misfolding and aggregation. Proc Natl Acad Sci U S A 2001. [PMID: 11114163 PMCID: PMC14582 DOI: 10.1073/pnas.011454198] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Gram-negative bacteria, TEM-1 beta-lactamase provides the major mechanism of plasmid-mediated beta-lactam resistance. Natural variants of TEM-1 with increased antibiotic resistance have appeared in response to the use of extended-spectrum beta-lactam antibiotics (e.g., ceftazidime) and beta-lactamase inhibitors (e.g., clavulanic acid). Some of the variant enzymes are more efficient at catalyzing beta-lactam hydrolysis, whereas others are more resistant to inhibitors. M182T is a substitution observed in both types of variant TEM-1 beta-lactamases. This mutation is found only in combination with other amino acid substitutions, suggesting that it may correct defects introduced by other mutations that alter the specificity. An engineered core mutation, L76N, which diminishes the periplasmic beta-lactamase activity by 100-fold, was used as a model to understand the mechanism of suppression of the M182T mutation. Biochemical studies of the L76N enzyme alone and in combination with the M182T mutation indicate that the M182T substitution acts at the level of folding but does not affect the thermodynamic stability of TEM-1 beta-lactamase. Thus, the M182T substitution is an example of a naturally occurring mutation that has evolved to alter the folding pathway of a protein and confer a selective advantage during the evolution of drug resistance.
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36
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Abstract
The application of temperature-sensitive polymer (PNIPAAm) for the renaturation of beta-lactamase from inclusion bodies was investigated. It was observed that PNIPAAm was more effective than PEG in enhancing protein renaturation. At a concentration of 0.1%, PNIPAAm improved the yield of beta-lactamase activity by 41% from 46. 5 to 65.4 IU/mL, compared to 26% with PEG from 46.5 to 58.7 IU/mL. Kinetic study indicated that PNIPAAm did not significantly affect the initial rate of protein renaturation but did increase final activity yield. In the presence of PEG and PNIPAAm, the activity yields increased with temperature, indicating that hydrophobic interactions between denatured protein and polymer molecules contributed to the enhanced protein renaturation with polymers. The sequential addition approach, aiming at enhancing protein renaturation by reducing local protein concentration during renaturation, was also shown effective in enhancing protein renaturation, especially in the presence of polymers. With the sequential addition approach, the activity yield was increased by 60. 5% from 46.5 to 74.6 IU/mL with PNIPAAm. Similar behavior was also observed with PEG. PNIPAAm exhibited similar behavior as PEG on the renaturation of beta-lactamase in terms of temperature effect and concentration effect, indicating that the mechanism for enhanced protein renaturation for the two polymers might be similar. PNIPAAm exhibits a lower critical solution temperature (LCST) of 32 degrees C and can be effectively separated from aqueous solution and recycled. A protein renaturation process employing PNIPAAm, which offers the advantages of enhanced renaturation efficiency, minimum loss of protein aggregates, and ease of polymers recycling, was proposed.
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Affiliation(s)
- S C Lin
- Department of Chemical Engineering, National Chung Hsing University, Taichung, Taiwan, Republic of China.
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37
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Ruvinov SB, Thompson J, Sackett DL, Ginsburg A. Tetrameric N(5)-(L-1-carboxyethyl)-L-ornithine synthase: guanidine. HCl-induced unfolding and a low temperature requirement for refolding. Arch Biochem Biophys 1999; 371:115-23. [PMID: 10525296 DOI: 10.1006/abbi.1999.1429] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Guanidine x HCl (GdnHCl)-induced unfolding of tetrameric N(5)-(L-1-carboxyethyl)-L-ornithine synthase (CEOS; 141,300 M(r)) from Lactococcus lactis at pH 7.2 and 25 degrees C occurred in several phases. The enzyme was inactivated at approximately 1 M GdnHCl. A time-, temperature-, and concentration-dependent formation of soluble protein aggregates occurred at 0.5-1.5 M GdnHCl due to an increased exposure of apolar surfaces. A transition from tetramer to unfolded monomer was observed between 2 and 3.5 M GdnHCl (without observable dimer or trimer intermediates), as evidenced by tyrosyl and tryptophanyl fluorescence changes, sulfhydryl group exposure, loss of secondary structure, size-exclusion chromatography, and sedimentation equilibrium data. GdnHCl-induced dissociation and unfolding of tetrameric CEOS was concerted, and yields of reactivated CEOS by dilution from 5 M GdnHCl were improved when unfolding took place on ice rather than at 25 degrees C. Refolding and reconstitution of the enzyme were optimal at </=15 degrees C and yields of active tetramer increased as the concentration of unfolded subunits decreased. Refolding of unfolded subunits and active tetramer assembly upon 100-fold dilution from 5 M GdnHCl at 0 degrees C also was increased two- or fourfold (to 44 or 28% reactivation for 0.08 or 0.28 microM subunit, respectively) when incubated at 15 degrees C, pH 7.2, for 4 h with the Escherichia coli molecular chaperonin GroEL, ATP, MgCl(2), and KCl.
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Affiliation(s)
- S B Ruvinov
- Laboratory of Biochemistry, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892, USA
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Dziejman M, Kolmar H, Fritz HJ, Mekalanos JJ. ToxR co-operative interactions are not modulated by environmental conditions or periplasmic domain conformation. Mol Microbiol 1999; 31:305-17. [PMID: 9987131 DOI: 10.1046/j.1365-2958.1999.01173.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ToxR is a transmembrane regulatory protein that controls virulence gene expression in Vibrio cholerae. Previous experiments using lambda repressor-ToxR chimeric proteins and a lambda repressor-controlled reporter system (OR1 PR-lacZY) established that ToxR sequences can effectively dimerize the amino-terminal domain of lambda repressor in Escherichia coli. However, in E. coli, ToxR does not respond to environmental signals that control virulence gene expression in V. cholerae. Here, we report the results of experiments designed to test whether environmental signals that modulate virulence gene expression in V. cholerae also modulate a monomer to dimerization transition of lambda-ToxR chimeras. When the OR1 PR-lacZY reporter fusion and chimeric proteins were transferred to V. cholerae, we unexpectedly found that lambda-ToxR chimeras did not dimerize significantly. Interestingly, experiments evaluating the ability of lambda-ToxR proteins to form tetramers in E. coli suggested that lambda-ToxR dimers could act co-operatively. Using a redesigned reporter system containing multiple lambda operator sites (OR1 OR2 OR3 PR-lacZY), we found that lambda-ToxR could dimerize quite efficiently in V. cholerae. These data imply that multiple DNA binding sites might enhance the ability of ToxR to dimerize in V. cholerae and suggest that ToxR dimers might be capable of co-operative interactions. However, we falled to correlate a monomer-dimer transition of the lambda-ToxR chimeras with changes in virulence gene expression in response to environmental signals in V. cholerae. Finally, because of conflicting results in the literature, the importance of membrane localization of ToxR and dimerization of the ToxR periplasmic domain was re-evaluated. This was accomplished by measuring the ability of various chimeric proteins to activate toxin gene expression in both E. coli and V. cholerae. These assays suggest that, in V. cholerae, deletion of the transmembrane domain has a profound effect on ToxR activity, although it is not an absolute requirement when ToxR is dimerized by a heterologous domain. In addition, we noted differences in chimeric protein activity when expressed in E. coli and V. cholerae. A construct substituting the monomeric MalE domain for the periplasmic domain of ToxR was unable to activate a ctx::lacZ reporter fusion in E. coli. Although the addition of leucine zipper sequences to this construct resulted in enhanced activity of the chimera in E. coli, both chimeras were able to produce wild-type levels of toxin in V. cholerae. These data support the notion that dimerization of ToxR stimulates its activity as a transcriptional activator in E. coli. In V. cholerae, however, we present data that do not demonstrate a correlation between dimerization of the periplasmic domain and ToxR activity.
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Affiliation(s)
- M Dziejman
- Department of Microbiology and Molecular Genetics, Shipley Institute of Harvard Medical School, Boston, MA 02115, USA
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Uversky VN, Karnoup AS, Khurana R, Segel DJ, Doniach S, Fink AL. Association of partially-folded intermediates of staphylococcal nuclease induces structure and stability. Protein Sci 1999; 8:161-73. [PMID: 10210194 PMCID: PMC2144103 DOI: 10.1110/ps.8.1.161] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Staphylococcal nuclease forms three different partially-folded intermediates at low pH in the presence of low to moderate concentration of anions, differing in the amount of secondary structure, globularity, stability, and compactness. Although these intermediates are monomeric at low protein concentration (< or =0.25 mg/mL), increasing concentrations of protein result in the formation of dimers and soluble oligomers, ultimately leading to larger insoluble aggregates. Unexpectedly, increasing protein concentration not only led to association, but also to increased structure of the intermediates. The secondary structure, stability, and globularity of the two less-ordered partially-folded intermediates (A1 and A2) were substantially increased upon association, suggesting that aggregation induces structure. An excellent correlation was found between degree of association and amount of structure measured by different techniques, including circular dichroism, fluorescence, Fourier transform infrared spectroscopy (FTIR), and small-angle X-ray scattering. The associated states were also substantially more stable toward urea denaturation than the monomeric forms. A mechanism is proposed, in which the observed association of monomeric intermediates involves intermolecular interactions which correspond to those found intramolecularly in normal folding to the native state.
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Affiliation(s)
- V N Uversky
- Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064, USA
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Kendrick BS, Carpenter JF, Cleland JL, Randolph TW. A transient expansion of the native state precedes aggregation of recombinant human interferon-gamma. Proc Natl Acad Sci U S A 1998; 95:14142-6. [PMID: 9826667 PMCID: PMC24340 DOI: 10.1073/pnas.95.24.14142] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Aggregation of proteins, even under conditions favoring the native state, is a ubiquitous problem in biotechnology and biomedical engineering. Providing a mechanistic basis for the pathways that lead to aggregation should allow development of rational approaches for its prevention. We have chosen recombinant human interferon-gamma (rhIFN-gamma) as a model protein for a mechanistic study of aggregation. In the presence of 0.9 M guanidinium hydrochloride, rhIFN-gamma aggregates with first order kinetics, a process that is inhibited by addition of sucrose. We describe a pathway that accounts for both the observed first-order aggregation of rhIFN-gamma and the effect of sucrose. In this pathway, aggregation proceeds through a transient expansion of the native state. Sucrose shifts the equilibrium within the ensemble of rhIFN-gamma native conformations to favor the most compact native species over more expanded ones, thus stabilizing rhIFN-gamma against aggregation. This phenomenon is attributed to the preferential exclusion of sucrose from the protein surface. In addition, kinetic analysis combined with solution thermodynamics shows that only a small (9%) expansion surface area is needed to form the transient native state that precedes aggregation. The approaches used here link thermodynamics and aggregation kinetics to provide a powerful tool for understanding both the pathway of protein aggregation and the rational use of excipients to inhibit the process.
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Affiliation(s)
- B S Kendrick
- Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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41
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Xie Y, Lashuel HA, Miroy GJ, Dikler S, Kelly JW. Recombinant human retinol-binding protein refolding, native disulfide formation, and characterization. Protein Expr Purif 1998; 14:31-7. [PMID: 9758748 DOI: 10.1006/prep.1998.0944] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human retinol-binding protein (RBP) is a monomeric 21-kDa protein that is currently the subject of numerous studies owing to its role in the cellular uptake and utilization of retinol. When the RBP gene is overexpressed in Escherichia coli, inclusion bodies of aggregated RBP are found in the cells. These inclusion bodies are solubilized in 5.0 M GdmCl containing 10 mM DTT. Refolding of RBP is carried out in the presence of vitamin A by diluting denatured and reduced RBP into a redox refolding buffer consisting of 3 mM cysteine/0.3 mM cystine at 4 degreesC. Ion exchange chromatography (HPLC) is utilized to purify refolded RBP to homogeneity as demonstrated by SDS-PAGE and electrospray MS. The native structure of refolded RBP was established by its ability to bind to vitamin A and the plasma protein transthyretin. The reconstitution of RBP outlined within affords a 50-60% overall yield, i.e., 73 mg of pure RBP/L of E. coli culture.
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Affiliation(s)
- Y Xie
- Department of Chemistry and the Skaggs Institute of Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, MB12, La Jolla, California, 92037, USA
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42
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Pfau JD, Taylor RK. Mutations in toxR and toxS that separate transcriptional activation from DNA binding at the cholera toxin gene promoter. J Bacteriol 1998; 180:4724-33. [PMID: 9721317 PMCID: PMC107489 DOI: 10.1128/jb.180.17.4724-4733.1998] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/1998] [Accepted: 06/21/1998] [Indexed: 11/20/2022] Open
Abstract
ToxR and ToxS are integral membrane proteins that activate the transcription of virulence genes in Vibrio cholerae. ToxR can be separated into three different domains: an N-terminal cytoplasmic DNA binding domain, a central transmembrane domain, and a C-terminal periplasmic domain. ToxS is thought to enhance ToxR-mediated transcriptional activation through a periplasmic interaction. By P22 challenge phage selection for DNA binding, in combination with a screen for cholera toxin gene transcription, 12 toxR and toxS positive control mutants producing variant ToxR proteins from the toxRS operon that bind to the cholera toxin promoter but that fail to activate transcription were isolated. One mutation in toxR specifies an E82K change in the predicted helix-loop-helix DNA binding domain and destroys ToxR-mediated activation. Seven toxR mutations included frameshifts and stop codons introduced into the periplasmic domain, and six of these mutations appeared to produce proteolytically processed shorter forms of ToxR, suggesting that even short periplasmic deletions alter the folding of ToxR in the periplasm. Deletion of toxS did not alter the steady-state level of ToxR, and ToxR was found to be capable of binding to DNA in the absence of ToxS even though it did not activate transcription. However, the ToxS L33S variant rendered ToxR susceptible to proteolysis, suggesting that the natural function of ToxS is to complex with ToxR. Therefore, certain alterations that map to the ToxR cytoplasmic DNA binding domain, to the periplasmic domain, or to ToxS separate DNA binding activity from activator function. These data support a model where proper assembly or stability of the periplasmic domain of ToxR is enhanced by ToxS. This chaperone-like activity of ToxS may be required for the formation of the transcriptional activation complex but not the ToxR-DNA complex.
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Affiliation(s)
- J D Pfau
- Department of Microbiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
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43
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Abstract
The disaccharide trehalose is produced in large quantities by diverse organisms during a variety of stresses. Trehalose prevents proteins from denaturing at high temperatures in vitro, but its function in stress tolerance in vivo is controversial. We report that trehalose stabilizes proteins in yeast cells during heat shock. Surprisingly, trehalose also suppresses the aggregation of denatured proteins, maintaining them in a partially-folded state from which they can be activated by molecular chaperones. The continued presence of trehalose, however, interferes with refolding, suggesting why it is rapidly hydrolyzed following heat shock. These findings reconcile conflicting reports on the role of trehalose in stress tolerance, provide a novel tool for accessing protein folding intermediates, and define new parameters for modulating stress tolerance and protein aggregation.
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Affiliation(s)
- M A Singer
- Department of Pathology, Howard Hughes Medical Institute, University of Chicago, Illinois 60637, USA
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44
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Abstract
Aggregation results in the formation of inclusion bodies, amyloid fibrils and folding aggregates. Substantial data support the hypothesis that partially folded intermediates are key precursors to aggregates, that aggregation involves specific intermolecular interactions and that most aggregates involve beta sheets.
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Affiliation(s)
- A L Fink
- Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064, USA.
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45
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Gervasoni P, Gehrig P, Plückthun A. Two conformational states of beta-lactamase bound to GroEL: a biophysical characterization. J Mol Biol 1998; 275:663-75. [PMID: 9466939 DOI: 10.1006/jmbi.1997.1481] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Escherichia coli RTEM beta-lactamase, in which both cysteine residues which form the single disulfide bond have been mutated to alanine residues, can form stable reversible complexes with GroEL under two different sets of conditions. Starting with the GdmCl-denatured enzyme, it is bound to GroEL in a state where no protons are protected against exchange with 2H2O, as determined by electrospray ionization mass spectrometry (ESI-MS). In contrast, when native protein is destabilized at high temperature and added to GroEL, a conformation is bound with 18 protected protons after two hours of exchange. While the high-temperature complex can form both with the wild-type enzyme (with intact disulfide bond) and the Cys-Ala double mutant, only the latter protein can form a complex starting from GdmCl denatured states. Thus, two different sets of conformations of the same protein can be bound, depending both on the conditions used to form the complex and on the intrinsic stability of the intermediate recognized by GroEL, and we have characterized the properties of both complexes.
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Affiliation(s)
- P Gervasoni
- Biochemisches Institut der Universität Zürich, Switzerland
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46
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Yang QH, Wu CL, Lin K, Li L. Low concentration of inducer favors production of active form of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase in Escherichia coli. Protein Expr Purif 1997; 10:320-4. [PMID: 9268678 DOI: 10.1006/prep.1997.0749] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Expression of chicken and rat liver bifunctional enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, in Escherichia coli encountered two common problems: the chicken enzyme was liable to proteolysis and the rat enzyme was prone to form inclusion bodies. Reducing the rate of protein synthesis by lowering either growth temperature or isopropyl-beta-D-thiogalactopyranoside (IPTG) concentration alleviated these two problems. Growth at 22 degrees C was optimum for expression of both enzymes. The optimum range of IPTG concentration for expression was 0.1-1 microM for the chicken liver bifunctional enzyme and 10 microM for rat liver enzyme. The components of growth medium also influenced the production. Compared with Luria-Bertani medium, an enriched medium-tryptone-phosphate medium-tripled the production of the active enzymes. Addition of glucose (0.2%) doubled the expression level of active chicken liver enzyme, but reduced the production of active rat liver enzyme to half the maximal level, while the phosphate in tryptone-phosphate medium had no effect on the production of the two enzymes.
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Affiliation(s)
- Q H Yang
- Shanghai Institute of Biochemistry, Academia Sinica, China
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47
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Betton JM, Hofnung M. Folding of a mutant maltose-binding protein of Escherichia coli which forms inclusion bodies. J Biol Chem 1996; 271:8046-52. [PMID: 8626487 DOI: 10.1074/jbc.271.14.8046] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The maltose-binding protein (MalE) of Escherichia coli is the periplasmic component of the transport system for malto-oligosaccharides. We have examined the characteristics of a Mal- mutant of malE corresponding to the double substitution Gly32 --> Asp/Ile33 --> Pro, MalE31, previously obtained by random mutagenesis. In vivo, the MalE31 precursor is efficiently processed, but the mature protein forms inclusion bodies in the periplasm. Furthermore, the accumulation of insoluble MalE31 is independent of its cellular localization; MalE31 lacking its signal sequence forms inclusion bodies in the cytoplasm. The native MalE31 protein can be purified by affinity chromatography from inclusion bodies after denaturation by 8 M urea. The renatured protein exhibits full maltose binding affinity (Kd= 9 x 10(-7) M), suggesting that its folded structure is similar to that of the wild-type protein. Unfolding/refolding experiments show that MalE31 is less stable (-5. 5 kcal/mol) than the wild-type protein (-9.5 kcal/mol) and that folding intermediates have a high tendency to form aggregates. In conclusion, the observed phenotype of cells expressing malE31 can be explained by a defective folding pathway of the protein.
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Affiliation(s)
- J M Betton
- Département des Biotechnologies, Institut Pasteur, 25, rue du Docteur Roux, 75015 Paris, France
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48
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Abstract
Many heterologous polypeptides fail to fold into their native state when expressed in Escherichia coli; instead, they are either degraded by the cellular proteolytic machinery or accumulate in insoluble form, typically as inclusion bodies. Misfolding is a particularly vexing problem in the expression of mammalian proteins, especially those that are composed of multiple subunits, have several disulfide bonds, or contain prosthetic groups. Fortunately, bacteria exhibit a remarkable physiological plasticity that can be successfully exploited to improve protein folding. Significant yields of active heterologous proteins have been obtained through strategies that include the co-expression of homologous or heterologous folding accessory proteins, the optimization of growth conditions, and the use of fusion proteins. A flood of recent reports documenting the successful production of complex eukaryotic proteins in active form have demonstrated that bacteria can provide the proper environment for the folding of the vast majority of recombinant polypeptides.
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Affiliation(s)
- G Georgiou
- Department of Chemical Engineering, University of Texas, Austin, 78712, USA
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