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Abdul-Ganiyu R, Venegas LA, Wang X, Puerner C, Arkowitz RA, Kay BK, Stone DE. Phosphorylated Gβ is a directional cue during yeast gradient tracking. Sci Signal 2021; 14:14/682/eabf4710. [PMID: 33975981 DOI: 10.1126/scisignal.abf4710] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Budding yeast cells interpret shallow pheromone gradients from cells of the opposite mating type, polarize their growth toward the pheromone source, and fuse at the chemotropic growth site. We previously proposed a deterministic, gradient-sensing model that explains how yeast cells switch from the intrinsically positioned default polarity site (DS) to the gradient-aligned chemotropic site (CS) at the plasma membrane. Because phosphorylation of the mating-specific Gβ subunit is thought to be important for this process, we developed a biosensor that bound to phosphorylated but not unphosphorylated Gβ and monitored its spatiotemporal dynamics to test key predictions of our gradient-sensing model. In mating cells, the biosensor colocalized with both Gβ and receptor reporters at the DS and then tracked with them to the CS. The biosensor concentrated on the leading side of the tracking Gβ and receptor peaks and was the first to arrive and stop tracking at the CS. Our data showed that the concentrated localization of phosphorylated Gβ correlated with the tracking direction and final position of the G protein and receptor, consistent with the idea that gradient-regulated phosphorylation and dephosphorylation of Gβ contributes to gradient sensing. Cells expressing a nonphosphorylatable mutant form of Gβ exhibited defects in gradient tracking, orientation toward mating partners, and mating efficiency.
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Affiliation(s)
- Rashida Abdul-Ganiyu
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Leon A Venegas
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xin Wang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Charles Puerner
- Université Côte D'Azur, CNRS, INSERM, Institute of Biology Valrose (iBV), Parc Valrose, Nice, France.,Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH 03755, USA
| | - Robert A Arkowitz
- Université Côte D'Azur, CNRS, INSERM, Institute of Biology Valrose (iBV), Parc Valrose, Nice, France
| | - Brian K Kay
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - David E Stone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
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Miller CJ, McGinnis JE, Martinez MJ, Wang G, Zhou J, Simmons E, Amet T, Abdeen SJ, Van Huysse JW, Bowsher RR, Kay BK. FN3-based monobodies selective for the receptor binding domain of the SARS-CoV-2 spike protein. N Biotechnol 2021; 62:79-85. [PMID: 33556628 PMCID: PMC7863792 DOI: 10.1016/j.nbt.2021.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 01/19/2021] [Accepted: 01/31/2021] [Indexed: 12/17/2022]
Abstract
A phage library displaying 1010 variants of the fibronectin type III (FN3) domain was affinity selected with the biotinylated form of the receptor binding domain (RBD, residues 319-541) of the SARS-CoV-2 virus spike protein. Nine binding FN3 variants (i.e. monobodies) were recovered, representing four different primary structures. Soluble forms of the monobodies bound to several different preparations of the RBD and the S1 spike subunit, with affinities ranging from 3 to 14 nM as measured by bio-layer interferometry. Three of the four monobodies bound selectively to the RBD of SARS-CoV-2, with the fourth monobody showing slight cross-reactivity to the RBD of SARS-CoV-1 virus. Examination of binding to the spike fragments and its trimeric form revealed that the monobodies recognise at least three overlapping epitopes on the RBD of SARS-CoV-2. While pairwise tests failed to identify a monobody pair that could bind simultaneously to the RBD, one monobody could simultaneously bind to the RBD with the ectodomain of the cellular receptor angiotensin converting enzyme 2 (ACE2). All four monobodies successfully bound the RBD after overexpression in Chinese hamster ovary (CHO) cells as fusions to the Fc domain of human IgG1.
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Affiliation(s)
- Christina J Miller
- Tango Biosciences, Inc., 2201 W. Campbell Park Drive, Chicago, IL 60612 USA
| | | | - Michael J Martinez
- Tango Biosciences, Inc., 2201 W. Campbell Park Drive, Chicago, IL 60612 USA
| | - Guangli Wang
- Euprotein Inc., 675 US Highway 1, Suite 129, North Brunswick, NJ 08902 USA
| | - Jian Zhou
- LifeTein LLC, 100 Randolph Road, Suite 2D, Somerset, NJ 08873 USA
| | - Erica Simmons
- B2S Life Sciences, 97 East Monroe Street, Franklin, IN 46131 USA
| | - Tohti Amet
- B2S Life Sciences, 97 East Monroe Street, Franklin, IN 46131 USA
| | - Sanofar J Abdeen
- B2S Life Sciences, 97 East Monroe Street, Franklin, IN 46131 USA
| | | | - Ronald R Bowsher
- B2S Life Sciences, 97 East Monroe Street, Franklin, IN 46131 USA
| | - Brian K Kay
- Tango Biosciences, Inc., 2201 W. Campbell Park Drive, Chicago, IL 60612 USA.
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McGinnis JE, Kay BK. Generation of recombinant affinity reagents against a two-phosphosite epitope of ATF2. N Biotechnol 2018; 45:45-50. [PMID: 29107187 DOI: 10.1016/j.nbt.2017.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/12/2017] [Accepted: 10/24/2017] [Indexed: 11/24/2022]
Abstract
Activating Transcription Factor 2 (ATF2) plays an important role in mammalian cell proliferation, apoptosis and DNA repair. Its activation is dependent on the sequential phosphorylation of residue threonine 71 (T71) followed by threonine 69 (T69) in its transactivation domain. While these modifications can be directed by a variety of kinases, the time to reach full phosphorylation is dependent on which signaling pathway has been activated, which is thought to be important for proper temporal regulation. To explore this phenomenon further, there have been ongoing efforts to generate affinity reagents for monitoring phosphorylation events in cellular assays. While phospho-specific antibodies have been valuable tools for monitoring cell signaling events, those raised against a peptide containing two or more adjacent phosphosites tend to cross-react with that peptide's various phospho-states, rendering such reagents unusable for studying sequential phosphorylation. As an alternative, we have employed the N-terminal Forkhead-associated 1 (FHA1) domain of yeast Rad53p as a scaffold to generate recombinant affinity reagents via phage display and were successful in generating a set of reagents that can distinguish between the dual-phosphorylated epitope, 63-IVADQpTPpTPTRFLK-77, and the mono-phosphorylated epitope, 63-IVADQpTPTPTRFLK-77, in the human ATF2 transactivation domain.
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Affiliation(s)
- Jennifer E McGinnis
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Ave., MBRB 4318, MC 567, Chicago, IL 60607 USA.
| | - Brian K Kay
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Ave., MBRB 4318, MC 567, Chicago, IL 60607 USA
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Generating a recombinant phosphothreonine-binding domain for a phosphopeptide of the human transcription factor, c-Myc. N Biotechnol 2018; 45:36-44. [PMID: 29763736 DOI: 10.1016/j.nbt.2018.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/28/2018] [Accepted: 05/02/2018] [Indexed: 11/21/2022]
Abstract
Transcription factor c-Myc is an oncoprotein that is regulated at the post-translational level through phosphorylation of two conserved residues, Serine 62 (Ser62) and Threonine 58 (Thr58). A highly specific tool capable of recognizing Myc via pThr58 is needed to monitor activation and localization. Through phage display, we have isolated 10 engineered Forkhead-associated (FHA) domains that selectively bind to a phosphothreonine (pThr)-containing peptide (53-FELLPpTPPLSPS-64) segment of human c-Myc. One domain variant was observed to bind to the Myc-pThr58 peptide with a KD value of 800 nM and had >1000-fold discrimination between the phosphorylated and non-phosphorylated peptide. The crystal structure of the engineered FHA Myc-pThr-binding domain (Myc-pTBD) was solved in complex with its cognate ligand. The Myc-pTBD was observed to be structurally similar to the yeast Rad9 FHA1 domain, except that its β4-β5 and β10-β11 loops form a hydrophobic pocket to facilitate the interaction between the domain and the peptide ligand. The Myc-pTBD's specificity for its cognate ligand was demonstrated to be on a par with 3 commercial polyclonal antibodies, suggesting that this recombinant reagent is a viable alternative to antibodies for monitoring Myc regulation.
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A Recombinant Affinity Reagent Specific for a Phosphoepitope of Akt1. Int J Mol Sci 2018; 19:ijms19113305. [PMID: 30355958 PMCID: PMC6274716 DOI: 10.3390/ijms19113305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/10/2018] [Accepted: 10/16/2018] [Indexed: 11/17/2022] Open
Abstract
The serine/threonine-protein kinase, Akt1, plays an important part in mammalian cell growth, proliferation, migration and angiogenesis, and becomes activated through phosphorylation. To monitor phosphorylation of threonine 308 in Akt1, we developed a recombinant phosphothreonine-binding domain (pTBD) that is highly selective for the Akt1 phosphopeptide. A phage-display library of variants of the Forkhead-associated 1 (FHA1) domain of yeast Rad53p was screened by affinity selection to the phosphopeptide, 301-KDGATMKpTFCGTPEY-315, and yielded 12 binding clones. The strongest binders have equilibrium dissociation constants of 160–180 nanomolar and are phosphothreonine-specific in binding. The specificity of one Akt1-pTBD was compared to commercially available polyclonal antibodies (pAbs) generated against the same phosphopeptide. The Akt1-pTBD was either equal to or better than three pAbs in detecting the Akt1 pT308 phosphopeptide in ELISAs.
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Gorman K, McGinnis J, Kay B. Generating FN3-Based Affinity Reagents Through Phage Display. ACTA ACUST UNITED AC 2018; 10:e39. [PMID: 29927113 DOI: 10.1002/cpch.39] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Antibodies are useful tools for detecting individual proteins in complex samples and for learning about their location, amount, binding partners, and function in cells. Unfortunately, generating antibodies is time consuming and laborious, and their affinity and/or specificity is often limited. This protocol offers a fast and inexpensive alternative to generate antibody surrogates through phage display of a library of fibronectin type III (FN3) monobody variants and affinity selection for binders. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Kevin Gorman
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Jennifer McGinnis
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Brian Kay
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
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7
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Venegas LA, Pershad K, Bankole O, Shah N, Kay BK. A comparison of phosphospecific affinity reagents reveals the utility of recombinant Forkhead-associated domains in recognizing phosphothreonine-containing peptides. N Biotechnol 2016; 33:537-43. [PMID: 26772725 DOI: 10.1016/j.nbt.2015.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/21/2015] [Accepted: 12/29/2015] [Indexed: 12/14/2022]
Abstract
Phosphorylation is an important post-translational event that has a wide array of functional consequences. With advances in the ability of various technologies in revealing and mapping new phosphosites in proteins, it is equally important to develop affinity reagents that can monitor such post-translational modifications in eukaryotic cells. While monoclonal and polyclonal antibodies have been shown to be useful in assessing the phosphoproteome, we have expanded our efforts to exploit the Forkhead-associated 1 (FHA1) domain as scaffold for generating recombinant affinity reagents that recognize phosphothreonine-containing peptides. A phage display library of FHA1 variants was screened by affinity selection with 15 phosphothreonine-containing peptides corresponding to various human transcription factors and kinases, including human Myc, calmodulin-dependent protein kinase II (CaMKII), and extracellular-signal regulated kinases 1 and 2 (ERK1/2). The library yielded binding variants against 10 targets (66% success rate); success was largely determined by what residue occurred at the +3 position (C-terminal) to the pThr moiety (i.e., pT+3). The FHA domains binding Myc, CaMKII, and ERK1/2 were characterized and compared against commercially available antibodies. All FHA domains were shown to be phosphorylation-dependent and phosphothreonine-specific in their binding, unlike several commercial monoclonal and polyclonal antibodies. Both the pThr and the residue at the pT+3 position were major factors in defining the specificity of the FHA domains.
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Affiliation(s)
- Leon A Venegas
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Kritika Pershad
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Oluwadamilola Bankole
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Noman Shah
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Brian K Kay
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
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8
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Modular peptide binding: From a comparison of natural binders to designed armadillo repeat proteins. J Struct Biol 2014; 185:147-62. [DOI: 10.1016/j.jsb.2013.07.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 07/26/2013] [Accepted: 07/27/2013] [Indexed: 11/23/2022]
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Koerber JT, Thomsen ND, Hannigan BT, Degrado WF, Wells JA. Nature-inspired design of motif-specific antibody scaffolds. Nat Biotechnol 2013; 31:916-21. [PMID: 23955275 PMCID: PMC3795957 DOI: 10.1038/nbt.2672] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 07/17/2013] [Indexed: 12/26/2022]
Abstract
Aberrant changes in post-translational modifications (PTMs) such as phosphorylation underlie a majority of human diseases. However, detection and quantification of PTMs for diagnostic or biomarker applications often requires monoclonal PTM-specific antibodies, which are challenging to generate using traditional antibody-generation platforms. Here we outline a general strategy for producing synthetic PTM-specific antibodies by engineering a motif-specific ‘hot spot’ into an antibody scaffold. Inspired by a natural phosphate-binding motif, we designed antibody scaffolds with hot spots specific for phosphoserine, phosphothreonine, or phosphotyrosine. Crystal structures of the phospho-specific antibodies revealed two distinct modes of phosphoresidue recognition. Our data suggest that each hot spot functions independently of the surrounding scaffold, as phage display antibody libraries using these scaffolds yielded >50 phospho- and target-specific antibodies against 70% of target peptides. Ultimately, our motif-specific scaffold strategy may provide a general solution for the rapid, robust development of monoclonal anti-PTM antibodies for signaling, diagnostic and therapeutic applications.
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Affiliation(s)
- James T Koerber
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, USA
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Pershad K, Kay BK. Generating thermal stable variants of protein domains through phage display. Methods 2012; 60:38-45. [PMID: 23276752 DOI: 10.1016/j.ymeth.2012.12.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 12/17/2012] [Accepted: 12/19/2012] [Indexed: 12/13/2022] Open
Abstract
Often in protein design research, one desires to generate thermally stable variants of a protein or domain. One route to identifying mutations that yield domains that remain folded and active at a higher temperature is through the use of directed evolution. A library of protein domain variants can be generated by mutagenic PCR, expressed on the surface of bacteriophage M13, and subjected to heat, such that the unfolded forms of the domain, showing reduced or no binding activity, are lost during subsequent affinity selection, whereas variants that still retain binding to their target are selected and enriched with each subsequent round of affinity selection. This approach takes advantage of the fact that bacteriophage M13 particles are heat stable and resistant to many proteases and protein denaturants. We present the application of this general approach to generating thermally stable variants of a eukaryotic peptide-binding domain. The benefits of producing such variants are that they typically express at high levels in Escherichia coli (30-60 mg/L shake flask) and remain soluble in solution at higher concentrations for longer periods of time than the wild-type form of the domain. The process of library generation and screening generally requires about one month of effort, and yields variants with >10 °C increase in thermal stability, as measured in a simple fluorescence-based thermal shift assay. It is anticipated that thermally stable variants will serve as excellent scaffolds for generating affinity reagents to a variety of targets of interest.
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Affiliation(s)
- Kritika Pershad
- Department of Biological Sciences, University of Illinois at Chicago, 845 W. Taylor St., 3240 SES-MC 066, Chicago, IL 60607-7060, USA
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