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Ó'Fágáin C. Protein Stability: Enhancement and Measurement. Methods Mol Biol 2023; 2699:369-419. [PMID: 37647007 DOI: 10.1007/978-1-0716-3362-5_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
This chapter defines protein stability, emphasizes its importance, and surveys the field of protein stabilization, with summary reference to a selection of 2014-2021 publications. One can enhance stability, particularly by protein engineering strategies but also by chemical modification and by other means. General protocols are set out on how to measure a given protein's (i) kinetic thermal stability and (ii) oxidative stability and (iii) how to undertake chemical modification of a protein in solution.
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Affiliation(s)
- Ciarán Ó'Fágáin
- School of Biotechnology, Dublin City University, Dublin, Ireland.
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2
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Raeeszadeh-Sarmazdeh M, Boder ET. Yeast Surface Display: New Opportunities for a Time-Tested Protein Engineering System. Methods Mol Biol 2022; 2491:3-25. [PMID: 35482182 DOI: 10.1007/978-1-0716-2285-8_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Yeast surface display has proven to be a powerful tool for the discovery of antibodies and other novel binding proteins and for engineering the affinity and selectivity of existing proteins for their targets. In the decades since the first demonstrations of the approach, the range of yeast display applications has greatly expanded to include many different protein targets and has grown to encompass methods for rapid protein characterization. Here, we briefly summarize the development of yeast display methodologies and highlight several selected examples of recent applications to timely and challenging protein engineering and characterization problems.
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Affiliation(s)
| | - Eric T Boder
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA.
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3
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Cluet D, Vergier B, Levy NP, Dehau L, Thurman A, Amri I, Spichty M. Titration of apparent in-cellula affinities of protein-protein interactions. Chembiochem 2021; 23:e202100640. [PMID: 34932835 DOI: 10.1002/cbic.202100640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/21/2021] [Indexed: 11/07/2022]
Abstract
A genetic assay permits simultaneous quantification of two interacting proteins and their bound fraction at the single-cell level using flow cytometry. Apparent in-cellula affinities of protein-protein interactions can be extracted from the acquired data through a titration-like analysis. The applicability of this approach is demonstrated on a diverse set of interactions with proteins from different families and organisms and with in-vitro dissociation constants ranging from picomolar to micromolar.
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Affiliation(s)
- David Cluet
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France
| | - Blandine Vergier
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France
| | - Nicolas-Pierre Levy
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France
| | - Lucie Dehau
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France
| | - Alexandre Thurman
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France
| | - Ikram Amri
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon cedex 07, France
| | - Martin Spichty
- Laboratoire d'Innovation Moléculaire et Applications, Université de Strasbourg -, Centre National de la Recherche Scientifique, Université de Haute-Alsace, 3 bis rue Alfred Werner, 68057, Mulhouse Cedex, France
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4
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Cluet D, Amri I, Vergier B, Léault J, Audibert A, Grosjean C, Calabrési D, Spichty M. A Quantitative Tri-fluorescent Yeast Two-hybrid System: From Flow Cytometry to In cellula Affinities. Mol Cell Proteomics 2020; 19:701-715. [PMID: 32015065 PMCID: PMC7124468 DOI: 10.1074/mcp.tir119.001692] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 01/31/2020] [Indexed: 12/14/2022] Open
Abstract
We present a technological advancement for the estimation of the affinities of Protein-Protein Interactions (PPIs) in living cells. A novel set of vectors is introduced that enables a quantitative yeast two-hybrid system based on fluorescent fusion proteins. The vectors allow simultaneous quantification of the reaction partners (Bait and Prey) and the reporter at the single-cell level by flow cytometry. We validate the applicability of this system on a small but diverse set of PPIs (eleven protein families from six organisms) with different affinities; the dissociation constants range from 117 pm to 17 μm After only two hours of reaction, expression of the reporter can be detected even for the weakest PPI. Through a simple gating analysis, it is possible to select only cells with identical expression levels of the reaction partners. As a result of this standardization of expression levels, the mean reporter levels directly reflect the affinities of the studied PPIs. With a set of PPIs with known affinities, it is straightforward to construct an affinity ladder that permits rapid classification of PPIs with thus far unknown affinities. Conventional software can be used for this analysis. To permit automated analysis, we provide a graphical user interface for the Python-based FlowCytometryTools package.
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Affiliation(s)
- David Cluet
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France
| | - Ikram Amri
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France
| | - Blandine Vergier
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France
| | - Jérémie Léault
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France
| | - Astrid Audibert
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France
| | - Clémence Grosjean
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France
| | - Dylan Calabrési
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France
| | - Martin Spichty
- Laboratoire de Biologie et Modé lisation de la Cellule, Ecole Normale Supé rieure de Lyon, CNRS, Université Lyon 1, Université de Lyon, 46 allée d'Italie, 69364 Lyon cedex 07, France.
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5
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Abstract
This article defines protein stability, emphasizes its importance and surveys the field of protein stabilization, with summary reference to a selection of 2009-2015 publications. One can enhance stability by, in particular, protein engineering strategies and by chemical modification (including conjugation) in solution. General protocols are set out on how to measure a given protein's (1) kinetic thermal stability, and (2) oxidative stability, and (3) how to undertake chemical modification of a protein in solution.
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Affiliation(s)
- Ciarán Ó'Fágáin
- School of Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.
- National Centre for Sensor Research, Dublin City University, Glasnevin, Dublin 9, Ireland.
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6
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Generating High-Accuracy Peptide-Binding Data in High Throughput with Yeast Surface Display and SORTCERY. Methods Mol Biol 2016; 1414:233-47. [PMID: 27094295 DOI: 10.1007/978-1-4939-3569-7_14] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Library methods are widely used to study protein-protein interactions, and high-throughput screening or selection followed by sequencing can identify a large number of peptide ligands for a protein target. In this chapter, we describe a procedure called "SORTCERY" that can rank the affinities of library members for a target with high accuracy. SORTCERY follows a three-step protocol. First, fluorescence-activated cell sorting (FACS) is used to sort a library of yeast-displayed peptide ligands according to their affinities for a target. Second, all sorted pools are deep sequenced. Third, the resulting data are analyzed to create a ranking. We demonstrate an application of SORTCERY to the problem of ranking peptide ligands for the anti-apoptotic regulator Bcl-xL.
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7
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Reich LL, Dutta S, Keating AE. SORTCERY-A High-Throughput Method to Affinity Rank Peptide Ligands. J Mol Biol 2014; 427:2135-50. [PMID: 25311858 DOI: 10.1016/j.jmb.2014.09.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 08/13/2014] [Accepted: 09/24/2014] [Indexed: 10/24/2022]
Abstract
Uncovering the relationships between peptide and protein sequences and binding properties is critical for successfully predicting, re-designing and inhibiting protein-protein interactions. Systematically collected data that link protein sequence to binding are valuable for elucidating determinants of protein interaction but are rare in the literature because such data are experimentally difficult to generate. Here we describe SORTCERY, a high-throughput method that we have used to rank hundreds of yeast-displayed peptides according to their affinities for a target interaction partner. The procedure involves fluorescence-activated cell sorting of a library, deep sequencing of sorted pools and downstream computational analysis. We have developed theoretical models and statistical tools that assist in planning these stages. We demonstrate SORTCERY's utility by ranking 1026 BH3 (Bcl-2 homology 3) peptides with respect to their affinities for the anti-apoptotic protein Bcl-xL. Our results are in striking agreement with measured affinities for 19 individual peptides with dissociation constants ranging from 0.1 to 60nM. High-resolution ranking can be used to improve our understanding of sequence-function relationships and to support the development of computational models for predicting and designing novel interactions.
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Affiliation(s)
- Lothar Luther Reich
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
| | - Sanjib Dutta
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
| | - Amy E Keating
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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Gee EPS, Yüksel D, Stultz CM, Ingber DE. SLLISWD sequence in the 10FNIII domain initiates fibronectin fibrillogenesis. J Biol Chem 2013; 288:21329-21340. [PMID: 23740248 DOI: 10.1074/jbc.m113.462077] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fibronectin (FN) assembly into extracellular matrix is tightly regulated and essential to embryogenesis and wound healing. FN fibrillogenesis is initiated by cytoskeleton-derived tensional forces transmitted across transmembrane integrins onto RGD binding sequences within the tenth FN type III (10FNIII) domains. These forces unfold 10FNIII to expose cryptic FN assembly sites; however, a specific sequence has not been identified in 10FNIII. Our past steered molecular dynamics simulations modeling 10FNIII unfolding by force at its RGD loop predicted a mechanical intermediate with a solvent-exposed N terminus spanning the A and B β-strands. Here, we experimentally confirm that the predicted 23-residue cryptic peptide 1 (CP1) initiates FN multimerization, which is mediated by interactions with 10FNIII that expose hydrophobic surfaces that support 8-anilino-1-napthalenesulfonic acid binding. Localization of multimerization activity to the C terminus led to the discovery of a minimal 7-amino acid "multimerization sequence" (SLLISWD), which induces polymerization of FN and the clotting protein fibrinogen in addition to enhancing FN fibrillogenesis in fibroblasts. A point mutation at Trp-6 that reduces exposure of hydrophobic sites for 8-anilino-1-napthalenesulfonic acid binding and β-structure formation inhibits FN multimerization and prevents physiological cell-based FN assembly in culture. We propose a model for cell-mediated fibrillogenesis whereby cell traction force initiates a cascade of intermolecular exchange starting with the unfolding of 10FNIII to expose the multimerization sequence, which interacts with strand B of another 10FNIII domain via a Trp-mediated β-strand exchange to stabilize a partially unfolded intermediate that propagates FN self-assembly.
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Affiliation(s)
- Elaine P S Gee
- From the Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115
| | - Deniz Yüksel
- From the Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115,; the Vascular Biology Program and Departments of Pathology and Surgery, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115
| | - Collin M Stultz
- the Institute of Medical Engineering and Sciences, Department of Electrical Engineering and Computer Science, and the Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and
| | - Donald E Ingber
- From the Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115,; the Vascular Biology Program and Departments of Pathology and Surgery, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115,; the Harvard School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138.
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9
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Diversity in genetic in vivo methods for protein-protein interaction studies: from the yeast two-hybrid system to the mammalian split-luciferase system. Microbiol Mol Biol Rev 2012; 76:331-82. [PMID: 22688816 DOI: 10.1128/mmbr.05021-11] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The yeast two-hybrid system pioneered the field of in vivo protein-protein interaction methods and undisputedly gave rise to a palette of ingenious techniques that are constantly pushing further the limits of the original method. Sensitivity and selectivity have improved because of various technical tricks and experimental designs. Here we present an exhaustive overview of the genetic approaches available to study in vivo binary protein interactions, based on two-hybrid and protein fragment complementation assays. These methods have been engineered and employed successfully in microorganisms such as Saccharomyces cerevisiae and Escherichia coli, but also in higher eukaryotes. From single binary pairwise interactions to whole-genome interactome mapping, the self-reassembly concept has been employed widely. Innovative studies report the use of proteins such as ubiquitin, dihydrofolate reductase, and adenylate cyclase as reconstituted reporters. Protein fragment complementation assays have extended the possibilities in protein-protein interaction studies, with technologies that enable spatial and temporal analyses of protein complexes. In addition, one-hybrid and three-hybrid systems have broadened the types of interactions that can be studied and the findings that can be obtained. Applications of these technologies are discussed, together with the advantages and limitations of the available assays.
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10
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Traxlmayr MW, Hasenhindl C, Hackl M, Stadlmayr G, Rybka JD, Borth N, Grillari J, Rüker F, Obinger C. Construction of a stability landscape of the CH3 domain of human IgG1 by combining directed evolution with high throughput sequencing. J Mol Biol 2012; 423:397-412. [PMID: 22846908 PMCID: PMC3469823 DOI: 10.1016/j.jmb.2012.07.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/13/2012] [Accepted: 07/18/2012] [Indexed: 12/21/2022]
Abstract
One of the most important but still poorly understood issues in protein chemistry is the relationship between sequence and stability of proteins. Here, we present a method for analyzing the influence of each individual residue on the foldability and stability of an entire protein. A randomly mutated library of the crystallizable fragment of human immunoglobulin G class 1 (IgG1-Fc) was expressed on the surface of yeast, followed by heat incubation at 79 °C and selection of stable variants that still bound to structurally specific ligands. High throughput sequencing allowed comparison of the mutation rate between the starting and selected library pools, enabling the generation of a stability landscape for the entire CH3 domain of human IgG1 at single residue resolution. Its quality was analyzed with respect to (i) the structure of IgG1-Fc, (ii) evolutionarily conserved positions and (iii) in silico calculations of the energy of unfolding of all variants in comparison with the wild-type protein. In addition, this new experimental approach allowed the assignment of functional epitopes of structurally specific ligands used for selection [Fc γ‐receptor I (CD64) and anti-human CH2 domain antibody] to distinct binding regions in the CH2 domain.
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Affiliation(s)
- Michael W Traxlmayr
- Christian Doppler Laboratory for Antibody Engineering, Vienna Institute of BioTechnology, BOKU University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
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11
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Boder ET, Raeeszadeh-Sarmazdeh M, Price JV. Engineering antibodies by yeast display. Arch Biochem Biophys 2012; 526:99-106. [PMID: 22450168 DOI: 10.1016/j.abb.2012.03.009] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 03/09/2012] [Accepted: 03/10/2012] [Indexed: 12/19/2022]
Abstract
Since its first application to antibody engineering 15 years ago, yeast display technology has been developed into a highly potent tool for both affinity maturing lead molecules and isolating novel antibodies and antibody-like species. Robust approaches to the creation of diversity, construction of yeast libraries, and library screening or selection have been elaborated, improving the quality of engineered molecules and certainty of success in an antibody engineering campaign and positioning yeast display as one of the premier antibody engineering technologies currently in use. Here, we summarize the history of antibody engineering by yeast surface display, approaches used in its application, and a number of examples highlighting the utility of this method for antibody engineering.
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Affiliation(s)
- Eric T Boder
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.
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12
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Hong Lim K, Hwang I, Park S. Biotin-assisted folding of streptavidin on the yeast surface. Biotechnol Prog 2011; 28:276-83. [DOI: 10.1002/btpr.721] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 07/31/2011] [Indexed: 01/28/2023]
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13
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Maksay G. Allostery in pharmacology: Thermodynamics, evolution and design. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 106:463-73. [DOI: 10.1016/j.pbiomolbio.2011.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/03/2011] [Indexed: 12/13/2022]
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Magliery TJ, Lavinder JJ, Sullivan BJ. Protein stability by number: high-throughput and statistical approaches to one of protein science's most difficult problems. Curr Opin Chem Biol 2011; 15:443-51. [PMID: 21498105 DOI: 10.1016/j.cbpa.2011.03.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/18/2011] [Accepted: 03/18/2011] [Indexed: 01/24/2023]
Abstract
Most proteins are only barely stable, which impedes research, complicates therapeutic applications, and makes proteins susceptible to pathologically destabilizing mutations. Our ability to predict the thermodynamic consequences of even single point mutations is still surprisingly limited, and established methods of measuring stability are slow. Recent advances are bringing protein stability studies into the high-throughput realm. Some methods are based on inferential read-outs such as activity, proteolytic resistance or split-protein fragment reassembly. Other methods use miniaturization of direct measurements, such as intrinsic fluorescence, H/D exchange, cysteine reactivity, aggregation and hydrophobic dye binding (DSF). Protein engineering based on statistical analysis (consensus and correlated occurrences of amino acids) is promising, but much work remains to understand and implement these methods.
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Affiliation(s)
- Thomas J Magliery
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA.
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15
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Abstract
This article defines protein stability, emphasizes its importance and surveys some notable recent publications (2004-2008) in the field of protein stability/stabilization. Knowledge of the factors stabilizing proteins has emerged from denaturation studies and from study of thermophilic (and other extremophilic) proteins. One can enhance stability by protein engineering strategies, the judicious use of solutes and additives, immobilization, and chemical modification in solution. General protocols are set out on how to measure the kinetic thermal stability of a given protein and how to undertake chemical modification of a protein in solution.
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Affiliation(s)
- Ciarán O'Fágáin
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland.
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16
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Lim KH, Madabhushi SR, Mann J, Neelamegham S, Park S. Disulfide trapping of protein complexes on the yeast surface. Biotechnol Bioeng 2010; 106:27-41. [PMID: 20047188 DOI: 10.1002/bit.22651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Protein complexes are common in nature and play important roles in biology, but studying the quaternary structure formation in vitro is challenging since it involves lengthy and expensive biochemical steps. There are frequent technical difficulties as well with the sensitivity and resolution of the assays. In this regard, a technique that can analyze protein-protein interactions in high throughput would be a useful experimental tool. Here, we introduce a combination of yeast display and disulfide trapping that we refer to as stabilization of transient and unstable complexes by engineered disulfide (STUCKED) that can be used to detect the formation of a broad spectrum of protein complexes on the yeast surface using fluorescence labeling. The technique uses an engineered intersubunit disulfide to covalently crosslink the subunits of a complex, so that the disulfide-trapped complex can be displayed on the yeast surface for detection and analysis. Transient protein complexes are difficult to display on the yeast surface, since they may dissociate before they can be detected due to a long induction period in yeast. To this end, we show that three different quaternary structures with the subunit dissociation constant K(d) approximately 0.5-20 microM, the antibody variable domain (Fv), the IL-8 dimer, and the p53-MDM2 complex, cannot be displayed on the yeast surface as a noncovalent complex. However, when we introduce an interchain disulfide between the subunits, all three systems are efficiently displayed on the yeast surface, showing that disulfide trapping can help display protein complexes that cannot be displayed otherwise. We also demonstrate that a disulfide forms only between the subunits that interact specifically, the displayed complexes exhibit functional characteristics that are expected of wt proteins, the mutations that decrease the affinity of subunit interaction also reduce the display efficiency, and most of the disulfide stabilized complexes are formed within the secretory pathway during export to the surface. Disulfide crosslinking is therefore a convenient way to study weak protein association in the context of yeast display.
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Affiliation(s)
- Kok Hong Lim
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York 14260, USA
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