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Pagar AD, Patil MD, Flood DT, Yoo TH, Dawson PE, Yun H. Recent Advances in Biocatalysis with Chemical Modification and Expanded Amino Acid Alphabet. Chem Rev 2021; 121:6173-6245. [PMID: 33886302 DOI: 10.1021/acs.chemrev.0c01201] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The two main strategies for enzyme engineering, directed evolution and rational design, have found widespread applications in improving the intrinsic activities of proteins. Although numerous advances have been achieved using these ground-breaking methods, the limited chemical diversity of the biopolymers, restricted to the 20 canonical amino acids, hampers creation of novel enzymes that Nature has never made thus far. To address this, much research has been devoted to expanding the protein sequence space via chemical modifications and/or incorporation of noncanonical amino acids (ncAAs). This review provides a balanced discussion and critical evaluation of the applications, recent advances, and technical breakthroughs in biocatalysis for three approaches: (i) chemical modification of cAAs, (ii) incorporation of ncAAs, and (iii) chemical modification of incorporated ncAAs. Furthermore, the applications of these approaches and the result on the functional properties and mechanistic study of the enzymes are extensively reviewed. We also discuss the design of artificial enzymes and directed evolution strategies for enzymes with ncAAs incorporated. Finally, we discuss the current challenges and future perspectives for biocatalysis using the expanded amino acid alphabet.
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Affiliation(s)
- Amol D Pagar
- Department of Systems Biotechnology, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
| | - Mahesh D Patil
- Department of Systems Biotechnology, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
| | - Dillon T Flood
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Tae Hyeon Yoo
- Department of Molecular Science and Technology, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon 16499, Korea
| | - Philip E Dawson
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Hyungdon Yun
- Department of Systems Biotechnology, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
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Emond S, Petek M, Kay EJ, Heames B, Devenish SRA, Tokuriki N, Hollfelder F. Accessing unexplored regions of sequence space in directed enzyme evolution via insertion/deletion mutagenesis. Nat Commun 2020; 11:3469. [PMID: 32651386 PMCID: PMC7351745 DOI: 10.1038/s41467-020-17061-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 06/01/2020] [Indexed: 11/22/2022] Open
Abstract
Insertions and deletions (InDels) are frequently observed in natural protein evolution, yet their potential remains untapped in laboratory evolution. Here we introduce a transposon-based mutagenesis approach (TRIAD) to generate libraries of random variants with short in-frame InDels, and screen TRIAD libraries to evolve a promiscuous arylesterase activity in a phosphotriesterase. The evolution exhibits features that differ from previous point mutagenesis campaigns: while the average activity of TRIAD variants is more compromised, a larger proportion has successfully adapted for the activity. Different functional profiles emerge: (i) both strong and weak trade-off between activities are observed; (ii) trade-off is more severe (20- to 35-fold increased kcat/KM in arylesterase with 60-400-fold decreases in phosphotriesterase activity) and (iii) improvements are present in kcat rather than just in KM, suggesting adaptive solutions. These distinct features make TRIAD an alternative to widely used point mutagenesis, accessing functional innovations and traversing unexplored fitness landscape regions.
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Affiliation(s)
- Stephane Emond
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK.
- Evonetix Ltd, Coldhams Business Park, Norman Way, Cambridge, CB1 3LH, UK.
| | - Maya Petek
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Emily J Kay
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
- Cancer Research UK Beatson Institute, Glasgow, G61 1BD, UK
| | - Brennen Heames
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
- Institute for Evolution and Biodiversity, Westfälische Wilhelms-Universität, Hüfferstrasse 1, 48149, Münster, Germany
| | - Sean R A Devenish
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
- Fluidic Analytics, The Paddocks Business Centre, Cherry Hinton Road, Cambridge, CB1 8DH, UK
| | - Nobuhiko Tokuriki
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK.
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Genetically encoded photochemical covalent crosslinking within the Hcp-1 self-assembling bacterial secretion machinery. Amino Acids 2018; 50:641-645. [DOI: 10.1007/s00726-017-2535-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 12/23/2017] [Indexed: 11/26/2022]
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Abstract
Phage Mu is the paradigm of a growing family of bacteriophages that infect a wide range of bacterial species and replicate their genome by replicative transposition. This molecular process, which is used by other mobile genetic elements to move within genomes, involves the profound rearrangement of the host genome [chromosome(s) and plasmid(s)] and can be exploited for the genetic analysis of the host bacteria and the in vivo cloning of host genes. In this chapter we review Mu-derived constructs that optimize the phage as a series of genetic tools that could inspire the development of similarly efficient tools from other transposable phages for a large spectrum of bacteria.
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Agostini F, Völler J, Koksch B, Acevedo‐Rocha CG, Kubyshkin V, Budisa N. Biocatalysis with Unnatural Amino Acids: Enzymology Meets Xenobiology. Angew Chem Int Ed Engl 2017; 56:9680-9703. [DOI: 10.1002/anie.201610129] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 12/13/2016] [Indexed: 01/18/2023]
Affiliation(s)
- Federica Agostini
- Institut für ChemieTechnische Universität Berlin Müller-Breslau-Strasse 10 10623 Berlin Germany
- Institute of Chemistry and Biochemistry—Organic ChemistryFreie Universität Berlin Takustrasse 3 14195 Berlin Germany
| | - Jan‐Stefan Völler
- Institut für ChemieTechnische Universität Berlin Müller-Breslau-Strasse 10 10623 Berlin Germany
| | - Beate Koksch
- Institute of Chemistry and Biochemistry—Organic ChemistryFreie Universität Berlin Takustrasse 3 14195 Berlin Germany
| | | | - Vladimir Kubyshkin
- Institut für ChemieTechnische Universität Berlin Müller-Breslau-Strasse 10 10623 Berlin Germany
| | - Nediljko Budisa
- Institut für ChemieTechnische Universität Berlin Müller-Breslau-Strasse 10 10623 Berlin Germany
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Biokatalyse mit nicht‐natürlichen Aminosäuren: Enzymologie trifft Xenobiologie. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201610129] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Liu SS, Wei X, Ji Q, Xin X, Jiang B, Liu J. A facile and efficient transposon mutagenesis method for generation of multi-codon deletions in protein sequences. J Biotechnol 2016; 227:27-34. [DOI: 10.1016/j.jbiotec.2016.03.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 03/17/2016] [Accepted: 03/21/2016] [Indexed: 12/17/2022]
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Ravikumar Y, Nadarajan SP, Hyeon Yoo T, Lee CS, Yun H. Incorporating unnatural amino acids to engineer biocatalysts for industrial bioprocess applications. Biotechnol J 2015; 10:1862-76. [DOI: 10.1002/biot.201500153] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 08/13/2015] [Accepted: 09/02/2015] [Indexed: 12/22/2022]
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Liu SS, Wei X, Dong X, Xu L, Liu J, Jiang B. Structural plasticity of green fluorescent protein to amino acid deletions and fluorescence rescue by folding-enhancing mutations. BMC BIOCHEMISTRY 2015. [PMID: 26206151 PMCID: PMC4513630 DOI: 10.1186/s12858-015-0046-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Green fluorescent protein (GFP) and its derivative fluorescent proteins (FPs) are among the most commonly used reporter systems for studying gene expression and protein interaction in biomedical research. Most commercially available FPs have been optimized for their oligomerization state to prevent potential structural constraints that may interfere with the native function of fused proteins. Other approach to reducing structural constraints may include minimizing the structure of GFPs. Previous studies in an enhanced GFP variant (EGFP) identified a series of deletions that can retain GFP fluorescence. In this study, we interrogated the structural plasticity of a UV-optimized GFP variant (GFP(UV)) to amino acid deletions, characterized the effects of deletions and explored the feasibility of rescuing the fluorescence of deletion mutants using folding-enhancing mutations. METHODS Transposon mutagenesis was used to screen amino acid deletions in GFP that led to fluorescent and nonfluorescent phenotypes. The fluorescent GFP mutants were characterized for their whole-cell fluorescence and fraction soluble. Fluorescent GFP mutants with internal deletions were purified and characterized for their spectral and folding properties. Folding-ehancing mutations were introduced to deletion mutants to rescue their compromised fluorescence. RESULTS We identified twelve amino acid deletions that can retain the fluorescence of GFP(UV). Seven of these deletions are either at the N- or C- terminus, while the other five are located at internal helices or strands. Further analysis suggested that the five internal deletions diminished the efficiency of protein folding and chromophore maturation. Protein expression under hypothermic condition or incorporation of folding-enhancing mutations could rescue the compromised fluorescence of deletion mutants. In addition, we generated dual deletion mutants that can retain GFP fluorescence. CONCLUSION Our results suggested that a "size-minimized" GFP may be developed by iterative incorporation of amino acid deletions, followed by fluorescence rescue with folding-enhancing mutations.
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Affiliation(s)
- Shu-su Liu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Xuan Wei
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Xue Dong
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Liang Xu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Jia Liu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China. .,Department of Chemistry and Biochemistry, University of Maryland, College Park, USA.
| | - Biao Jiang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
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Ravikumar Y, Nadarajan SP, Yoo TH, Lee CS, Yun H. Unnatural amino acid mutagenesis-based enzyme engineering. Trends Biotechnol 2015; 33:462-70. [PMID: 26088007 DOI: 10.1016/j.tibtech.2015.05.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/07/2015] [Accepted: 05/13/2015] [Indexed: 02/09/2023]
Abstract
Traditional enzyme engineering relies on substituting one amino acid by one of the other 19 natural amino acids to change the functional properties of an enzyme. However, incorporation of unnatural amino acids (UAAs) has been harnessed to engineer efficient enzymes for biocatalysis. Residue-specific and site-specific in vivo incorporation methods are becoming the preferred approach for producing enzymes with altered or improved functions. We describe the contribution of in vivo UAA incorporation methodologies to enzyme engineering as well as the future prospects for the field, including the integration of UAAs with other new advances in enzyme engineering.
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Affiliation(s)
- Yuvaraj Ravikumar
- School of Biotechnology, Department of Biochemistry, Yeungnam University, Gyeongsan, Gyeongbuk 712-749, Korea
| | | | - Tae Hyeon Yoo
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea
| | - Chong-soon Lee
- School of Biotechnology, Department of Biochemistry, Yeungnam University, Gyeongsan, Gyeongbuk 712-749, Korea
| | - Hyungdon Yun
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Korea.
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11
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In-frame amber stop codon replacement mutagenesis for the directed evolution of proteins containing non-canonical amino acids: identification of residues open to bio-orthogonal modification. PLoS One 2015; 10:e0127504. [PMID: 26011713 PMCID: PMC4444182 DOI: 10.1371/journal.pone.0127504] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 04/13/2015] [Indexed: 11/19/2022] Open
Abstract
Expanded genetic code approaches are a powerful means to add new and useful chemistry to proteins at defined residues positions. One such use is the introduction of non-biological reactive chemical handles for site-specific biocompatible orthogonal conjugation of proteins. Due to our currently limited information on the impact of non-canonical amino acids (nAAs) on the protein structure-function relationship, rational protein engineering is a “hit and miss” approach to selecting suitable sites. Furthermore, dogma suggests surface exposed native residues should be the primary focus for introducing new conjugation chemistry. Here we describe a directed evolution approach to introduce and select for in-frame codon replacement to facilitate engineering proteins with nAAs. To demonstrate the approach, the commonly reprogrammed amber stop codon (TAG) was randomly introduced in-frame in two different proteins: the bionanotechnologically important cyt b562 and therapeutic protein KGF. The target protein is linked at the gene level to sfGFP via a TEV protease site. In absence of a nAA, an in-frame TAG will terminate translation resulting in a non-fluorescent cell phenotype. In the presence of a nAA, TAG will encode for nAA incorporation so instilling a green fluorescence phenotype on E. coli. The presence of endogenously expressed TEV proteases separates in vivo target protein from its fusion to sfGFP if expressed as a soluble fusion product. Using this approach, we incorporated an azide reactive handle and identified residue positions amenable to conjugation with a fluorescence dye via strain-promoted azide-alkyne cycloaddition (SPAAC). Interestingly, best positions for efficient conjugation via SPAAC were residues whose native side chain were buried through analysis of their determined 3D structures and thus may not have been chosen through rational protein engineering. Molecular modeling suggests these buried native residues could become partially exposed on substitution to the azide containing nAA.
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12
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Currin A, Swainston N, Day PJ, Kell DB. Synthetic biology for the directed evolution of protein biocatalysts: navigating sequence space intelligently. Chem Soc Rev 2015; 44:1172-239. [PMID: 25503938 PMCID: PMC4349129 DOI: 10.1039/c4cs00351a] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Indexed: 12/21/2022]
Abstract
The amino acid sequence of a protein affects both its structure and its function. Thus, the ability to modify the sequence, and hence the structure and activity, of individual proteins in a systematic way, opens up many opportunities, both scientifically and (as we focus on here) for exploitation in biocatalysis. Modern methods of synthetic biology, whereby increasingly large sequences of DNA can be synthesised de novo, allow an unprecedented ability to engineer proteins with novel functions. However, the number of possible proteins is far too large to test individually, so we need means for navigating the 'search space' of possible protein sequences efficiently and reliably in order to find desirable activities and other properties. Enzymologists distinguish binding (Kd) and catalytic (kcat) steps. In a similar way, judicious strategies have blended design (for binding, specificity and active site modelling) with the more empirical methods of classical directed evolution (DE) for improving kcat (where natural evolution rarely seeks the highest values), especially with regard to residues distant from the active site and where the functional linkages underpinning enzyme dynamics are both unknown and hard to predict. Epistasis (where the 'best' amino acid at one site depends on that or those at others) is a notable feature of directed evolution. The aim of this review is to highlight some of the approaches that are being developed to allow us to use directed evolution to improve enzyme properties, often dramatically. We note that directed evolution differs in a number of ways from natural evolution, including in particular the available mechanisms and the likely selection pressures. Thus, we stress the opportunities afforded by techniques that enable one to map sequence to (structure and) activity in silico, as an effective means of modelling and exploring protein landscapes. Because known landscapes may be assessed and reasoned about as a whole, simultaneously, this offers opportunities for protein improvement not readily available to natural evolution on rapid timescales. Intelligent landscape navigation, informed by sequence-activity relationships and coupled to the emerging methods of synthetic biology, offers scope for the development of novel biocatalysts that are both highly active and robust.
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Affiliation(s)
- Andrew Currin
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- School of Chemistry , The University of Manchester , Manchester M13 9PL , UK
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
| | - Neil Swainston
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
- School of Computer Science , The University of Manchester , Manchester M13 9PL , UK
| | - Philip J. Day
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
- Faculty of Medical and Human Sciences , The University of Manchester , Manchester M13 9PT , UK
| | - Douglas B. Kell
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- School of Chemistry , The University of Manchester , Manchester M13 9PL , UK
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
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Reddington SC, Baldwin AJ, Thompson R, Brancale A, Tippmann EM, Jones DD. Directed evolution of GFP with non-natural amino acids identifies residues for augmenting and photoswitching fluorescence. Chem Sci 2015; 6:1159-1166. [PMID: 29560203 PMCID: PMC5811120 DOI: 10.1039/c4sc02827a] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 10/24/2014] [Indexed: 12/22/2022] Open
Abstract
Genetic code reprogramming allows proteins to sample new chemistry through the defined and targeted introduction of non-natural amino acids (nAAs). Many useful nAAs are derivatives of the natural aromatic amino acid tyrosine, with the para OH group replaced with useful but often bulkier substituents. Extending residue sampling by directed evolution identified positions in Green Fluorescent Protein tolerant to aromatic nAAs, including identification of novel sites that modulate fluorescence. Replacement of the buried L44 residue by photosensitive p-azidophenylalanine (azF) conferred environmentally sensitive photoswitching. In silico modelling of the L44azF dark state provided an insight into the mechanism of action through modulation of the hydrogen bonding network surrounding the chromophore. Targeted mutagenesis of T203 with aromatic nAAs to introduce π-stacking with the chromophore successfully generated red shifted versions of GFP. Incorporation of azF at residue 203 conferred high photosensitivity on sfGFP with even ambient light mediating a functional switch. Thus, engineering proteins with non-natural aromatic amino acids by surveying a wide residue set can introduce new and beneficial properties into a protein through the sampling of non-intuitive mutations. Coupled with retrospective in silico modelling, this will facilitate both our understanding of the impact of nAAs on protein structure and function, and future design endeavours.
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Affiliation(s)
- Samuel C Reddington
- School of Biosciences , Cardiff University , Cardiff CF10 3AT , UK . ; Tel: +44 (0)29 20874290
- School of Chemistry , Cardiff University , Cardiff , UK
| | - Amy J Baldwin
- School of Biosciences , Cardiff University , Cardiff CF10 3AT , UK . ; Tel: +44 (0)29 20874290
- School of Chemistry , Cardiff University , Cardiff , UK
| | - Rebecca Thompson
- School of Biosciences , Cardiff University , Cardiff CF10 3AT , UK . ; Tel: +44 (0)29 20874290
| | - Andrea Brancale
- School of Pharmacy and Pharmaceutical Sciences , Cardiff University , Cardiff , UK
| | | | - D Dafydd Jones
- School of Biosciences , Cardiff University , Cardiff CF10 3AT , UK . ; Tel: +44 (0)29 20874290
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14
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Arpino JAJ, Rizkallah PJ, Jones DD. Structural and dynamic changes associated with beneficial engineered single-amino-acid deletion mutations in enhanced green fluorescent protein. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2152-62. [PMID: 25084334 PMCID: PMC4118826 DOI: 10.1107/s139900471401267x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 05/31/2014] [Indexed: 01/23/2023]
Abstract
Single-amino-acid deletions are a common part of the natural evolutionary landscape but are rarely sampled during protein engineering owing to limited and prejudiced molecular understanding of mutations that shorten the protein backbone. Single-amino-acid deletion variants of enhanced green fluorescent protein (EGFP) have been identified by directed evolution with the beneficial effect of imparting increased cellular fluorescence. Biophysical characterization revealed that increased functional protein production and not changes to the fluorescence parameters was the mechanism that was likely to be responsible. The structure EGFP(D190Δ) containing a deletion within a loop revealed propagated changes only after the deleted residue. The structure of EGFP(A227Δ) revealed that a `flipping' mechanism was used to adjust for residue deletion at the end of a β-strand, with amino acids C-terminal to the deletion site repositioning to take the place of the deleted amino acid. In both variants new networks of short-range and long-range interactions are generated while maintaining the integrity of the hydrophobic core. Both deletion variants also displayed significant local and long-range changes in dynamics, as evident by changes in B factors compared with EGFP. Rather than being detrimental, deletion mutations can introduce beneficial structural effects through altering core protein properties, folding and dynamics, as well as function.
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Affiliation(s)
- James A. J. Arpino
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, Wales
| | | | - D. Dafydd Jones
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, Wales
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15
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Arpino JAJ, Reddington SC, Halliwell LM, Rizkallah PJ, Jones DD. Random single amino acid deletion sampling unveils structural tolerance and the benefits of helical registry shift on GFP folding and structure. Structure 2014; 22:889-98. [PMID: 24856363 PMCID: PMC4058518 DOI: 10.1016/j.str.2014.03.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 03/08/2014] [Accepted: 03/10/2014] [Indexed: 12/01/2022]
Abstract
Altering a protein’s backbone through amino acid deletion is a common evolutionary mutational mechanism, but is generally ignored during protein engineering primarily because its effect on the folding-structure-function relationship is difficult to predict. Using directed evolution, enhanced green fluorescent protein (EGFP) was observed to tolerate residue deletion across the breadth of the protein, particularly within short and long loops, helical elements, and at the termini of strands. A variant with G4 removed from a helix (EGFPG4Δ) conferred significantly higher cellular fluorescence. Folding analysis revealed that EGFPG4Δ retained more structure upon unfolding and refolded with almost 100% efficiency but at the expense of thermodynamic stability. The EGFPG4Δ structure revealed that G4 deletion caused a beneficial helical registry shift resulting in a new polar interaction network, which potentially stabilizes a cis proline peptide bond and links secondary structure elements. Thus, deletion mutations and registry shifts can enhance proteins through structural rearrangements not possible by substitution mutations alone. Using directed evolution, the impact of amino acid deletion on EGFP is explored Loops, helices, and strand termini are especially tolerant to amino acid deletion A deletion mutant that enhances cellular production and fluorescence is identified Structure reveals that a helical registry shift creates a new polar network
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Affiliation(s)
- James A J Arpino
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK
| | - Samuel C Reddington
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK
| | - Lisa M Halliwell
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK
| | - Pierre J Rizkallah
- School of Medicine, Cardiff University, WHRI, Main Building, Heath Park, Cardiff CF14 4XN, UK
| | - D Dafydd Jones
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK.
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16
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Jones DD, Arpino JAJ, Baldwin AJ, Edmundson MC. Transposon-based approaches for generating novel molecular diversity during directed evolution. Methods Mol Biol 2014; 1179:159-172. [PMID: 25055777 DOI: 10.1007/978-1-4939-1053-3_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This chapter introduces a set of transposon-based methods that were developed to sample trinucleotide deletion, trinucleotide replacement, and domain insertion. Each approach has a common initial step that utilizes an engineered version of the Mu transposon called MuDel. The inherent low sequence specificity of MuDel results in its random insertion into target DNA during in vitro transposition. Removal of the transposon using a type IIS restriction endonuclease generates blunt-end random breaks at a frequency of one per target gene and the concomitant loss of 3 bp. Self-ligation or insertion of another DNA cassette results in the sampling of trinucleotide deletion or trinucleotide substitution/domain insertion, respectively.
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Affiliation(s)
- D Dafydd Jones
- School of Biosciences, Cardiff University, Museum Avenue, Cardiff, CF10 3AT, UK,
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Arpino JAJ, Czapinska H, Piasecka A, Edwards WR, Barker P, Gajda MJ, Bochtler M, Jones DD. Structural basis for efficient chromophore communication and energy transfer in a constructed didomain protein scaffold. J Am Chem Soc 2012; 134:13632-40. [PMID: 22822710 DOI: 10.1021/ja301987h] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The construction of useful functional biomolecular components not currently part of the natural repertoire is central to synthetic biology. A new light-capturing ultra-high-efficiency energy transfer protein scaffold has been constructed by coupling the chromophore centers of two normally unrelated proteins: the autofluorescent protein enhanced green fluorescent protein (EGFP) and the heme-binding electron transfer protein cytochrome b(562) (cyt b(562)). Using a combinatorial domain insertion strategy, a variant was isolated in which resonance energy transfer from the donor EGFP to the acceptor cyt b(562) was close to 100% as evident by virtually full fluorescence quenching on heme binding. The fluorescence signal of the variant was also sensitive to the reactive oxygen species H(2)O(2), with high signal gain observed due to the release of heme. The structure of oxidized holoprotein, determined to 2.75 Å resolution, revealed that the two domains were arranged side-by-side in a V-shape conformation, generating an interchromophore distance of ~17 Å (14 Å edge-to-edge). Critical to domain arrangement is the formation of a molecular pivot point between the two domains as a result of different linker sequence lengths at each domain junction and formation of a predominantly polar interdomain interaction surface. The retrospective structural analysis has provided an explanation for the basis of the observed highly efficient energy transfer through chromophore arrangement in the directly evolved protein scaffold and provides an insight into the molecular principles by which to design new proteins with coupled functions.
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Affiliation(s)
- James A J Arpino
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, United Kingdom
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18
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Reddington SC, Tippmann EM, Jones DD. Residue choice defines efficiency and influence of bioorthogonal protein modification via genetically encoded strain promoted Click chemistry. Chem Commun (Camb) 2012; 48:8419-21. [PMID: 22801454 DOI: 10.1039/c2cc31887c] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
GFP and a FRET compatible dye were used to assess the influence of genetically encoded aryl azide positioning on Click chemistry-based protein conjugation. While modification efficiency of the sampled mutants using a strain promoted reaction varied by as much as ∼10 fold, there was no simple correlation with accessibility of the aryl azide on GFP's surface. One labeled GFP mutant (Gln204AzPhe) exhibited high efficiency FRET (∼90%) and an unprecedented pseudo-Stokes shift of 126 nm.
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19
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Abstract
Site-specific incorporation of unnatural amino acids into proteins in vivo relies on the genetic reassignment of nonsense or quadruplet codons. Here, we describe a general procedure for the random introduction of these codons into open reading frames resulting in protein libraries that are scanned with unnatural amino acid residues. These libraries can enable large-scale mutagenesis experiments aimed at understanding and improving protein function.
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Affiliation(s)
- Jia Liu
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA
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20
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Antonczak AK, Morris J, Tippmann EM. Advances in the mechanism and understanding of site-selective noncanonical amino acid incorporation. Curr Opin Struct Biol 2011; 21:481-7. [DOI: 10.1016/j.sbi.2011.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 04/28/2011] [Indexed: 01/01/2023]
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21
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Spicer CD, Davis BG. Palladium-mediated site-selective Suzuki-Miyaura protein modification at genetically encoded aryl halides. Chem Commun (Camb) 2011; 47:1698-700. [PMID: 21206952 DOI: 10.1039/c0cc04970k] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Site-specific genetic incorporation of unnatural p-halophenylalanine amino acid residues as 'tags' coupled with Pd(0)-mediated Suzuki-Miyuara 'modification' has been enabled by discovery of an effective small molecule palladium scavenger.
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Affiliation(s)
- Christopher D Spicer
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
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22
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