101
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Steinbrecher T, Zhu C, Wang L, Abel R, Negron C, Pearlman D, Feyfant E, Duan J, Sherman W. Predicting the Effect of Amino Acid Single-Point Mutations on Protein Stability—Large-Scale Validation of MD-Based Relative Free Energy Calculations. J Mol Biol 2017; 429:948-963. [DOI: 10.1016/j.jmb.2016.12.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 12/02/2016] [Accepted: 12/02/2016] [Indexed: 12/22/2022]
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102
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Steinbrecher T, Abel R, Clark A, Friesner R. Free Energy Perturbation Calculations of the Thermodynamics of Protein Side-Chain Mutations. J Mol Biol 2017; 429:923-929. [DOI: 10.1016/j.jmb.2017.03.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/28/2017] [Accepted: 03/02/2017] [Indexed: 01/20/2023]
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103
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Rutsdottir G, Härmark J, Weide Y, Hebert H, Rasmussen MI, Wernersson S, Respondek M, Akke M, Højrup P, Koeck PJB, Söderberg CAG, Emanuelsson C. Structural model of dodecameric heat-shock protein Hsp21: Flexible N-terminal arms interact with client proteins while C-terminal tails maintain the dodecamer and chaperone activity. J Biol Chem 2017; 292:8103-8121. [PMID: 28325834 PMCID: PMC5427286 DOI: 10.1074/jbc.m116.766816] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 03/16/2017] [Indexed: 01/14/2023] Open
Abstract
Small heat-shock proteins (sHsps) prevent aggregation of thermosensitive client proteins in a first line of defense against cellular stress. The mechanisms by which they perform this function have been hard to define due to limited structural information; currently, there is only one high-resolution structure of a plant sHsp published, that of the cytosolic Hsp16.9. We took interest in Hsp21, a chloroplast-localized sHsp crucial for plant stress resistance, which has even longer N-terminal arms than Hsp16.9, with a functionally important and conserved methionine-rich motif. To provide a framework for investigating structure-function relationships of Hsp21 and understanding these sequence variations, we developed a structural model of Hsp21 based on homology modeling, cryo-EM, cross-linking mass spectrometry, NMR, and small-angle X-ray scattering. Our data suggest a dodecameric arrangement of two trimer-of-dimer discs stabilized by the C-terminal tails, possibly through tail-to-tail interactions between the discs, mediated through extended IXVXI motifs. Our model further suggests that six N-terminal arms are located on the outside of the dodecamer, accessible for interaction with client proteins, and distinct from previous undefined or inwardly facing arms. To test the importance of the IXVXI motif, we created the point mutant V181A, which, as expected, disrupts the Hsp21 dodecamer and decreases chaperone activity. Finally, our data emphasize that sHsp chaperone efficiency depends on oligomerization and that client interactions can occur both with and without oligomer dissociation. These results provide a generalizable workflow to explore sHsps, expand our understanding of sHsp structural motifs, and provide a testable Hsp21 structure model to inform future investigations.
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Affiliation(s)
| | - Johan Härmark
- the School of Technology and Health, KTH/Royal Institute of Technology and Department of Biosciences and Nutrition, Karolinska Institutet, SE-171 77 Stockholm, Sweden, and
| | - Yoran Weide
- From the Departments of Biochemistry and Structural Biology and
| | - Hans Hebert
- the School of Technology and Health, KTH/Royal Institute of Technology and Department of Biosciences and Nutrition, Karolinska Institutet, SE-171 77 Stockholm, Sweden, and
| | - Morten I Rasmussen
- the Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark
| | | | | | | | - Peter Højrup
- the Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark
| | - Philip J B Koeck
- the School of Technology and Health, KTH/Royal Institute of Technology and Department of Biosciences and Nutrition, Karolinska Institutet, SE-171 77 Stockholm, Sweden, and
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104
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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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105
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Goldsmith M, Aggarwal N, Ashani Y, Jubran H, Greisen PJ, Ovchinnikov S, Leader H, Baker D, Sussman JL, Goldenzweig A, Fleishman SJ, Tawfik DS. Overcoming an optimization plateau in the directed evolution of highly efficient nerve agent bioscavengers. Protein Eng Des Sel 2017; 30:333-345. [DOI: 10.1093/protein/gzx003] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/10/2017] [Indexed: 11/13/2022] Open
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106
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Cheema J, Faraldos JA, O'Maille PE. REVIEW: Epistasis and dominance in the emergence of catalytic function as exemplified by the evolution of plant terpene synthases. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2017; 255:29-38. [PMID: 28131339 DOI: 10.1016/j.plantsci.2016.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 10/17/2016] [Accepted: 11/12/2016] [Indexed: 06/06/2023]
Abstract
Epistasis, the interaction between mutations and the genetic background, is a pervasive force in evolution that is difficult to predict yet derives from a simple principle - biological systems are interconnected. Therefore, one effect may be intimately linked to another, hence interdependent. Untangling epistatic interactions between and within genes is a vibrant area of research. Deriving a mechanistic understanding of epistasis is a major challenge. Particularly, elucidating how epistasis can attenuate the effects of otherwise dominant mutations that control phenotypes. Using the emergence of terpene cyclization in specialized metabolism as an excellent example, this review describes the process of discovery and interpretation of dominance and epistasis in relation to current efforts. Specifically, we outline experimental approaches to isolating epistatic networks of mutations in protein structure, formally quantifying epistatic interactions, then building biochemical models with chemical mechanisms in efforts to achieve an understanding of the physical basis for epistasis. From these models we describe informed conjectures about past evolutionary events that underlie the emergence, divergence and specialization of terpene synthases to illustrate key principles of the constraining forces of epistasis in enzyme function.
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Affiliation(s)
- Jitender Cheema
- John Innes Centre, Computational and Systems Biology, Norwich Research Park, Norwich NR4 7UH, UK.
| | - Juan A Faraldos
- John Innes Centre, Department of Metabolic Biology, Norwich Research Park, Norwich NR4 7UH, UK.
| | - Paul E O'Maille
- John Innes Centre, Department of Metabolic Biology, Norwich Research Park, Norwich NR4 7UH, UK; Institute of Food Research, Food & Health Programme, Norwich Research Park, Norwich NR4 7UA, UK.
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107
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Abstract
α-Helical coiled coils are ubiquitous protein-folding and protein-interaction domains in which two or more α-helical chains come together to form bundles. Through a combination of bioinformatics analysis of many thousands of natural coiled-coil sequences and structures, plus empirical protein engineering and design studies, there is now a deep understanding of the sequence-to-structure relationships for this class of protein architecture. This has led to considerable success in rational design and what might be termed in biro de novo design of simple coiled coils, which include homo- and hetero-meric parallel dimers, trimers and tetramers. In turn, these provide a toolkit for directing the assembly of both natural proteins and more complex designs in protein engineering, materials science and synthetic biology. Moving on, the increased and improved use of computational design is allowing access to coiled-coil structures that are rare or even not observed in nature, for example α-helical barrels, which comprise five or more α-helices and have central channels into which different functions may be ported. This chapter reviews all of these advances, outlining improvements in our knowledge of the fundamentals of coiled-coil folding and assembly, and highlighting new coiled coil-based materials and applications that this new understanding is opening up. Despite considerable progress, however, challenges remain in coiled-coil design, and the next decade promises to be as productive and exciting as the last.
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Affiliation(s)
- Derek N Woolfson
- School of Chemistry, University of Bristol, BS8 1TS, Bristol, UK.
- School of Biochemistry, University of Bristol, BS8 1TD, Bristol, UK.
- BrisSynBio, Life Sciences Building, University of Bristol, BS8 1TQ, Bristol, UK.
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108
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Zou J, Song B, Simmerling C, Raleigh D. Experimental and Computational Analysis of Protein Stabilization by Gly-to-d-Ala Substitution: A Convolution of Native State and Unfolded State Effects. J Am Chem Soc 2016; 138:15682-15689. [PMID: 27934019 PMCID: PMC5442443 DOI: 10.1021/jacs.6b09511] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The rational and predictable enhancement of protein stability is an important goal in protein design. Most efforts target the folded state, however stability is the free energy difference between the folded and unfolded states thus both are suitable targets. Strategies directed at the unfolded state usually seek to decrease chain entropy by introducing cross-links or by replacing glycines. Cross-linking has led to mixed results. Replacement of glycine with an l-amino acid, while reducing the entropy of the unfolded state, can introduce unfavorable steric interactions in the folded state, since glycine is often found in conformations that require a positive φ angle such as helical C-capping motifs or type I' and II″ β-turns. l-Amino acids are strongly disfavored in these conformations, but d-amino acids are not. However, there are few reported examples and conflicting results have been obtained when glycines are replaced with d-Ala. We critically examine the effect of Gly-to-d-Ala substitutions on protein stability using experimental approaches together with molecular dynamics simulations and free energy calculations. The data, together with a survey of high resolution structures, show that the vast majority of proteins can be stabilized by substitution of C-capping glycines with d-Ala. Sites suitable for substitutions can be identified via sequence alignment with a high degree of success. Steric clashes in the native state due to the new side chain are rarely observed, but are likely responsible for the destabilizing or null effect observed for the small subset of Gly-to-d-Ala substitutions which are not stabilizing. Changes in backbone solvation play less of a role. Favorable candidates for d-Ala substitution can be identified using a rapid algorithm based on molecular mechanics.
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Affiliation(s)
- Junjie Zou
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400
| | - Benben Song
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400
| | - Carlos Simmerling
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794-3400
| | - Daniel Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400
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109
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The role of small in-frame insertions/deletions in inherited eye disorders and how structural modelling can help estimate their pathogenicity. Orphanet J Rare Dis 2016; 11:125. [PMID: 27628848 PMCID: PMC5024463 DOI: 10.1186/s13023-016-0505-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/22/2016] [Indexed: 01/05/2023] Open
Abstract
Background Although the majority of small in-frame insertions/deletions (indels) has no/little affect on protein function, a small subset of these changes has been causally associated with genetic disorders. Notably, the molecular mechanisms and frequency by which they give rise to disease phenotypes remain largely unknown. The aim of this study is to provide insights into the role of in-frame indels (≤21 nucleotides) in two genetically heterogeneous eye disorders. Results One hundred eighty-one probands with childhood cataracts and 486 probands with retinal dystrophy underwent multigene panel testing in a clinical diagnostic laboratory. In-frame indels were collected and evaluated both clinically and in silico. Variants that could be modeled in the context of protein structure were identified and analysed using integrative structural modeling. Overall, 55 small in-frame indels were detected in 112 of 667 probands (16.8 %); 17 of these changes were novel to this study and 18 variants were reported clinically. A reliable model of the corresponding protein sequence could be generated for 8 variants. Structural modeling indicated a diverse range of molecular mechanisms of disease including disruption of secondary and tertiary protein structure and alteration of protein-DNA binding sites. Conclusions In childhood cataract and retinal dystrophy subjects, one small in-frame indel is clinically reported in every ~37 individuals tested. The clinical utility of computational tools evaluating these changes increases when the full complexity of the involved molecular mechanisms is embraced. Electronic supplementary material The online version of this article (doi:10.1186/s13023-016-0505-0) contains supplementary material, which is available to authorized users.
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110
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Engineering ancestral protein hyperstability. Biochem J 2016; 473:3611-3620. [PMID: 27528732 DOI: 10.1042/bcj20160532] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 08/15/2016] [Indexed: 01/23/2023]
Abstract
Many experimental analyses and proposed scenarios support that ancient life was thermophilic. In congruence with this hypothesis, proteins encoded by reconstructed sequences corresponding to ancient phylogenetic nodes often display very high stability. Here, we show that such 'reconstructed ancestral hyperstability' can be further engineered on the basis of a straightforward approach that uses exclusively information afforded by the ancestral reconstruction process itself. Since evolution does not imply continuous progression, screening of the mutations between two evolutionarily related resurrected ancestral proteins may identify mutations that further stabilize the most stable one. To explore this approach, we have used a resurrected thioredoxin corresponding to the last common ancestor of the cyanobacterial, Deinococcus and Thermus groups (LPBCA thioredoxin), which has a denaturation temperature of ∼123°C. This high value is within the top 0.1% of the denaturation temperatures in the ProTherm database and, therefore, achieving further stabilization appears a priori as a challenging task. Nevertheless, experimental comparison with a resurrected thioredoxin corresponding to the last common ancestor of bacteria (denaturation temperature of ∼115°C) immediately identifies three mutations that increase the denaturation temperature of LPBCA thioredoxin to ∼128°C. Comparison between evolutionarily related resurrected ancestral proteins thus emerges as a simple approach to expand the capability of ancestral reconstruction to search sequence space for extreme protein properties of biotechnological interest. The fact that ancestral sequences for many phylogenetic nodes can be derived from a single alignment of modern sequences should contribute to the general applicability of this approach.
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111
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Goldenzweig A, Goldsmith M, Hill SE, Gertman O, Laurino P, Ashani Y, Dym O, Unger T, Albeck S, Prilusky J, Lieberman RL, Aharoni A, Silman I, Sussman JL, Tawfik DS, Fleishman SJ. Automated Structure- and Sequence-Based Design of Proteins for High Bacterial Expression and Stability. Mol Cell 2016; 63:337-346. [PMID: 27425410 PMCID: PMC4961223 DOI: 10.1016/j.molcel.2016.06.012] [Citation(s) in RCA: 299] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/18/2016] [Accepted: 06/07/2016] [Indexed: 12/28/2022]
Abstract
Upon heterologous overexpression, many proteins misfold or aggregate, thus resulting in low functional yields. Human acetylcholinesterase (hAChE), an enzyme mediating synaptic transmission, is a typical case of a human protein that necessitates mammalian systems to obtain functional expression. We developed a computational strategy and designed an AChE variant bearing 51 mutations that improved core packing, surface polarity, and backbone rigidity. This variant expressed at ∼2,000-fold higher levels in E. coli compared to wild-type hAChE and exhibited 20°C higher thermostability with no change in enzymatic properties or in the active-site configuration as determined by crystallography. To demonstrate broad utility, we similarly designed four other human and bacterial proteins. Testing at most three designs per protein, we obtained enhanced stability and/or higher yields of soluble and active protein in E. coli. Our algorithm requires only a 3D structure and several dozen sequences of naturally occurring homologs, and is available at http://pross.weizmann.ac.il. A new computational method is used to stabilize five recalcitrant proteins Designed variants show higher expression and stability with unmodified function A designed human acetylcholinesterase variant expresses solubly in bacteria The method is fully automated and implemented on a webserver
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Affiliation(s)
- Adi Goldenzweig
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Moshe Goldsmith
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shannon E Hill
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Or Gertman
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel
| | - Paola Laurino
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yacov Ashani
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel; Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Orly Dym
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tamar Unger
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shira Albeck
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Jaime Prilusky
- Bioinformatics & Biological Computing Unit, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Amir Aharoni
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel
| | - Israel Silman
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Joel L Sussman
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Sarel J Fleishman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
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112
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Abstract
A popular and successful strategy in semi-rational design of protein stability is the use of evolutionary information encapsulated in homologous protein sequences. Consensus design is based on the hypothesis that at a given position, the respective consensus amino acid contributes more than average to the stability of the protein than non-conserved amino acids. Here, we review the consensus design approach, its theoretical underpinnings, successes, limitations and challenges, as well as providing a detailed guide to its application in protein engineering.
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Affiliation(s)
- Benjamin T Porebski
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Faculty of Medicine, Monash University, Clayton, Victoria 3800, Australia Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Ashley M Buckle
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Faculty of Medicine, Monash University, Clayton, Victoria 3800, Australia
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113
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Using natural sequences and modularity to design common and novel protein topologies. Curr Opin Struct Biol 2016; 38:26-36. [PMID: 27270240 DOI: 10.1016/j.sbi.2016.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/13/2016] [Accepted: 05/18/2016] [Indexed: 02/07/2023]
Abstract
Protein design is still a challenging undertaking, often requiring multiple attempts or iterations for success. Typically, the source of failure is unclear, and scoring metrics appear similar between successful and failed cases. Nevertheless, the use of sequence statistics, modularity and symmetry from natural proteins, combined with computational design both at the coarse-grained and atomistic levels is propelling a new wave of design efforts to success. Here we highlight recent examples of design, showing how the wealth of natural protein sequence and topology data may be leveraged to reduce the search space and increase the likelihood of achieving desired outcomes.
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