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Chaisupa P, Wright RC. State-of-the-art in engineering small molecule biosensors and their applications in metabolic engineering. SLAS Technol 2024; 29:100113. [PMID: 37918525 DOI: 10.1016/j.slast.2023.10.005] [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] [Received: 07/07/2023] [Revised: 10/18/2023] [Accepted: 10/25/2023] [Indexed: 11/04/2023]
Abstract
Genetically encoded biosensors are crucial for enhancing our understanding of how molecules regulate biological systems. Small molecule biosensors, in particular, help us understand the interaction between chemicals and biological processes. They also accelerate metabolic engineering by increasing screening throughput and eliminating the need for sample preparation through traditional chemical analysis. Additionally, they offer significantly higher spatial and temporal resolution in cellular analyte measurements. In this review, we discuss recent progress in in vivo biosensors and control systems-biosensor-based controllers-for metabolic engineering. We also specifically explore protein-based biosensors that utilize less commonly exploited signaling mechanisms, such as protein stability and induced degradation, compared to more prevalent transcription factor and allosteric regulation mechanism. We propose that these lesser-used mechanisms will be significant for engineering eukaryotic systems and slower-growing prokaryotic systems where protein turnover may facilitate more rapid and reliable measurement and regulation of the current cellular state. Lastly, we emphasize the utilization of cutting-edge and state-of-the-art techniques in the development of protein-based biosensors, achieved through rational design, directed evolution, and collaborative approaches.
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Affiliation(s)
- Patarasuda Chaisupa
- Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA 24061, United States
| | - R Clay Wright
- Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA 24061, United States; Translational Plant Sciences Center (TPSC), Virginia Tech, Blacksburg, VA 24061, United States.
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Blanchard PL, Knick BJ, Whelan SA, Hackel BJ. Hyperstable Synthetic Mini-Proteins as Effective Ligand Scaffolds. ACS Synth Biol 2023; 12:3608-3622. [PMID: 38010428 PMCID: PMC10822706 DOI: 10.1021/acssynbio.3c00409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Small, single-domain protein scaffolds are compelling sources of molecular binding ligands with the potential for efficient physiological transport, modularity, and manufacturing. Yet, mini-proteins require a balance between biophysical robustness and diversity to enable new functions. We tested the developability and evolvability of millions of variants of 43 designed libraries of synthetic 40-amino acid βαββ proteins with diversified sheet, loop, or helix paratopes. We discovered a scaffold library that yielded hundreds of binders to seven targets while exhibiting high stability and soluble expression. Binder discovery yielded 6-122 nM affinities without affinity maturation and Tms averaging ≥78 °C. Broader βαββ libraries exhibited varied developability and evolvability. Sheet paratopes were the most consistently developable, and framework 1 was the most evolvable. Paratope evolvability was dependent on target, though several libraries were evolvable across many targets while exhibiting high stability and soluble expression. Select βαββ proteins are strong starting points for engineering performant binders.
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Affiliation(s)
- Paul L. Blanchard
- Department of Chemical Engineering and Materials Science, University of Minnesota – Twin Cities, 421 Washington Avenue SE, Minneapolis, MN 55455
| | - Brandon J. Knick
- Department of Chemical Engineering and Materials Science, University of Minnesota – Twin Cities, 421 Washington Avenue SE, Minneapolis, MN 55455
| | - Sarah A. Whelan
- Department of Chemical Engineering and Materials Science, University of Minnesota – Twin Cities, 421 Washington Avenue SE, Minneapolis, MN 55455
| | - Benjamin J. Hackel
- Department of Chemical Engineering and Materials Science, University of Minnesota – Twin Cities, 421 Washington Avenue SE, Minneapolis, MN 55455
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Golinski AW, Holec PV, Mischler KM, Hackel BJ. Biophysical Characterization Platform Informs Protein Scaffold Evolvability. ACS COMBINATORIAL SCIENCE 2019; 21:323-335. [PMID: 30681831 PMCID: PMC6458986 DOI: 10.1021/acscombsci.8b00182] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Evolving specific molecular recognition function of proteins requires strategic navigation of a complex mutational landscape. Protein scaffolds aid evolution via a conserved platform on which a modular paratope can be evolved to alter binding specificity. Although numerous protein scaffolds have been discovered, the underlying properties that permit binding evolution remain unknown. We present an algorithm to predict a protein scaffold's ability to evolve novel binding function based upon computationally calculated biophysical parameters. The ability of 17 small proteins to evolve binding functionality across seven discovery campaigns was determined via magnetic activated cell sorting of 1010 yeast-displayed protein variants. Twenty topological and biophysical properties were calculated for 787 small protein scaffolds and reduced into independent components. Regularization deduced which extracted features best predicted binding functionality, providing a 4/6 true positive rate, a 9/11 negative predictive value, and a 4/6 positive predictive value. Model analysis suggests a large, disconnected paratope will permit evolved binding function. Previous protein engineering endeavors have suggested that starting with a highly developable (high producibility, stability, solubility) protein will offer greater mutational tolerance. Our results support this connection between developability and evolvability by demonstrating a relationship between protein production in the soluble fraction of Escherichia coli and the ability to evolve binding function upon mutation. We further explain the necessity for initial developability by observing a decrease in proteolytic stability of protein mutants that possess binding functionality over nonfunctional mutants. Future iterations of protein scaffold discovery and evolution will benefit from a combination of computational prediction and knowledge of initial developability properties.
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Affiliation(s)
- Alexander W. Golinski
- Department of Chemical Engineering and Materials Science, University of Minnesota−Twin Cities, 421 Washington Avenue Southeast, 356 Amundson Hall, Minneapolis, Minnesota 55455, United States
| | - Patrick V. Holec
- Department of Chemical Engineering and Materials Science, University of Minnesota−Twin Cities, 421 Washington Avenue Southeast, 356 Amundson Hall, Minneapolis, Minnesota 55455, United States
| | - Katelynn M. Mischler
- Department of Chemical Engineering and Materials Science, University of Minnesota−Twin Cities, 421 Washington Avenue Southeast, 356 Amundson Hall, Minneapolis, Minnesota 55455, United States
| | - Benjamin J. Hackel
- Department of Chemical Engineering and Materials Science, University of Minnesota−Twin Cities, 421 Washington Avenue Southeast, 356 Amundson Hall, Minneapolis, Minnesota 55455, United States
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Kruziki MA, Sarma V, Hackel BJ. Constrained Combinatorial Libraries of Gp2 Proteins Enhance Discovery of PD-L1 Binders. ACS COMBINATORIAL SCIENCE 2018; 20:423-435. [PMID: 29799714 DOI: 10.1021/acscombsci.8b00010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Engineered protein ligands are used for molecular therapy, diagnostics, and industrial biotechnology. The Gp2 domain is a 45-amino acid scaffold that has been evolved for specific, high-affinity binding to multiple targets by diversification of two solvent-exposed loops. Inspired by sitewise enrichment of select amino acids, including cysteine pairs, in earlier Gp2 discovery campaigns, we hypothesized that the breadth and efficiency of de novo Gp2 discovery will be aided by sitewise amino acid constraint within combinatorial library design. We systematically constructed eight libraries and comparatively evaluated their efficacy for binder discovery via yeast display against a panel of targets. Conservation of a cysteine pair at the termini of the first diversified paratope loop increased binder discovery 16-fold ( p < 0.001). Yet two other libraries with conserved cysteine pairs, within the second loop or an interloop pair, did not aid discovery thereby indicating site-specific impact. Via a yeast display protease resistance assay, Gp2 variants from the loop one cysteine pair library were 3.3 ± 2.1-fold ( p = 0.005) more stable than nonconstrained variants. Sitewise constraint of noncysteine residues-guided by previously evolved binders, natural Gp2 homology, computed stability, and structural analysis-did not aid discovery. A panel of binders to programmed death ligand 1 (PD-L1), a key target in cancer immunotherapy, were discovered from the loop 1 cysteine constraint library. Affinity maturation via loop walking resulted in strong, specific cellular PD-L1 affinity ( Kd = 6-9 nM).
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Affiliation(s)
- Max A. Kruziki
- University of Minnesota—Twin Cities, Department of Chemical Engineering and Materials Science, 421 Washington Avenue Southeast, Minneapolis, Minnesota 55455, United States
| | - Vidur Sarma
- University of Minnesota—Twin Cities, Department of Chemical Engineering and Materials Science, 421 Washington Avenue Southeast, Minneapolis, Minnesota 55455, United States
| | - Benjamin J. Hackel
- University of Minnesota—Twin Cities, Department of Chemical Engineering and Materials Science, 421 Washington Avenue Southeast, Minneapolis, Minnesota 55455, United States
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Wrenbeck EE, Faber MS, Whitehead TA. Deep sequencing methods for protein engineering and design. Curr Opin Struct Biol 2017; 45:36-44. [PMID: 27886568 PMCID: PMC5440218 DOI: 10.1016/j.sbi.2016.11.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/01/2016] [Indexed: 11/27/2022]
Abstract
The advent of next-generation sequencing (NGS) has revolutionized protein science, and the development of complementary methods enabling NGS-driven protein engineering have followed. In general, these experiments address the functional consequences of thousands of protein variants in a massively parallel manner using genotype-phenotype linked high-throughput functional screens followed by DNA counting via deep sequencing. We highlight the use of information rich datasets to engineer protein molecular recognition. Examples include the creation of multiple dual-affinity Fabs targeting structurally dissimilar epitopes and engineering of a broad germline-targeted anti-HIV-1 immunogen. Additionally, we highlight the generation of enzyme fitness landscapes for conducting fundamental studies of protein behavior and evolution. We conclude with discussion of technological advances.
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Affiliation(s)
- Emily E Wrenbeck
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, United States
| | - Matthew S Faber
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States
| | - Timothy A Whitehead
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, United States; Departments of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI 48824, United States.
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Woldring DR, Holec PV, Stern LA, Du Y, Hackel BJ. A Gradient of Sitewise Diversity Promotes Evolutionary Fitness for Binder Discovery in a Three-Helix Bundle Protein Scaffold. Biochemistry 2017; 56:1656-1671. [PMID: 28248518 DOI: 10.1021/acs.biochem.6b01142] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Engineered proteins provide clinically and industrially impactful molecules and utility within fundamental research, yet inefficiencies in discovering lead variants with new desired functionality, while maintaining stability, hinder progress. Improved function, which can result from a few strategic mutations, is fundamentally separate from discovering novel function, which often requires large leaps in sequence space. While a highly diverse combinatorial library covering immense sequence space would empower protein discovery, the ability to sample only a minor subset of sequence space and the typical destabilization of random mutations preclude this strategy. A balance must be reached. At library scale, compounding several destabilizing mutations renders many variants unable to properly fold and devoid of function. Broadly searching sequence space while reducing the level of destabilization may enhance evolution. We exemplify this balance with affibody, a three-helix bundle protein scaffold. Using natural ligand data sets, stability and structural computations, and deep sequencing of thousands of binding variants, a protein library was designed on a sitewise basis with a gradient of mutational levels across 29% of the protein. In direct competition of biased and uniform libraries, both with 1 × 109 variants, for discovery of 6 × 104 ligands (5 × 103 clusters) toward seven targets, biased amino acid frequency increased ligand discovery 13 ± 3-fold. Evolutionarily favorable amino acids, both globally and site-specifically, are further elucidated. The sitewise amino acid bias aids evolutionary discovery by reducing the level of mutant destabilization as evidenced by a midpoint of denaturation (62 ± 4 °C) 15 °C higher than that of unbiased mutants (47 ± 11 °C; p < 0.001). Sitewise diversification, identified by high-throughput evolution and rational library design, improves discovery efficiency.
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Affiliation(s)
- Daniel R Woldring
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities , 421 Washington Avenue Southeast, Minneapolis, Minnesota 55455, United States
| | - Patrick V Holec
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities , 421 Washington Avenue Southeast, Minneapolis, Minnesota 55455, United States
| | - Lawrence A Stern
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities , 421 Washington Avenue Southeast, Minneapolis, Minnesota 55455, United States
| | - Yang Du
- Molecular and Cellular Physiology, Stanford University , 279 Campus Drive, Stanford, California 94305, United States
| | - Benjamin J Hackel
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities , 421 Washington Avenue Southeast, Minneapolis, Minnesota 55455, United States
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