1
|
Verma H, Kaur J, Thakur V, Dhingra GG, Lal R. Comprehensive review on Haloalkane dehalogenase (LinB): a β-hexachlorocyclohexane (HCH) degrading enzyme. Arch Microbiol 2024; 206:380. [PMID: 39143366 DOI: 10.1007/s00203-024-04105-1] [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: 06/05/2024] [Revised: 08/02/2024] [Accepted: 08/05/2024] [Indexed: 08/16/2024]
Abstract
Haloalkane dehalogenase, LinB, is a member of the α/β hydrolase family of enzymes. It has a wide range of halogenated substrates, but, has been mostly studied in context of degradation of hexachlorocyclohexane (HCH) isomers, especially β-HCH (5-12% of total HCH isomers), which is the most recalcitrant and persistent among all the HCH isomers. LinB was identified to directly act on β-HCH in a one or two step transformation which decreases its toxicity manifold. Thereafter, many studies focused on LinB including its structure determination using X-ray crystallographic studies, structure comparison with other haloalkane dehalogenases, substrate specificity and kinetic studies, protein engineering and site-directed mutagenesis studies in search of better catalytic activity of the enzyme. LinB was mainly identified and characterized in bacteria belonging to sphingomonads. Detailed sequence comparison of LinB from different sphingomonads further revealed the residues critical for its activity and ability to catalyze either one or two step transformation of β-HCH. Association of LinB with IS6100 elements is also being discussed in detail in sphingomonads. In this review, we summarized vigorous efforts done by different research groups on LinB for developing better bioremediation strategies against HCH contamination. Also, kinetic studies, protein engineering and site directed mutagenesis studies discussed here forms the basis of further exploration of LinB's role as an efficient enzyme in bioremediation projects.
Collapse
Affiliation(s)
| | - Jasvinder Kaur
- Gargi College, University of Delhi, Delhi, 110007, India
| | | | | | - Rup Lal
- INSA, Acharya Narendra Dev College, University of Delhi, Govindpuri, Kalkaji, New Delhi, 110019, India.
| |
Collapse
|
2
|
Metzger BPH, Park Y, Starr TN, Thornton JW. Epistasis facilitates functional evolution in an ancient transcription factor. eLife 2024; 12:RP88737. [PMID: 38767330 PMCID: PMC11105156 DOI: 10.7554/elife.88737] [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: 05/22/2024] Open
Abstract
A protein's genetic architecture - the set of causal rules by which its sequence produces its functions - also determines its possible evolutionary trajectories. Prior research has proposed that the genetic architecture of proteins is very complex, with pervasive epistatic interactions that constrain evolution and make function difficult to predict from sequence. Most of this work has analyzed only the direct paths between two proteins of interest - excluding the vast majority of possible genotypes and evolutionary trajectories - and has considered only a single protein function, leaving unaddressed the genetic architecture of functional specificity and its impact on the evolution of new functions. Here, we develop a new method based on ordinal logistic regression to directly characterize the global genetic determinants of multiple protein functions from 20-state combinatorial deep mutational scanning (DMS) experiments. We use it to dissect the genetic architecture and evolution of a transcription factor's specificity for DNA, using data from a combinatorial DMS of an ancient steroid hormone receptor's capacity to activate transcription from two biologically relevant DNA elements. We show that the genetic architecture of DNA recognition consists of a dense set of main and pairwise effects that involve virtually every possible amino acid state in the protein-DNA interface, but higher-order epistasis plays only a tiny role. Pairwise interactions enlarge the set of functional sequences and are the primary determinants of specificity for different DNA elements. They also massively expand the number of opportunities for single-residue mutations to switch specificity from one DNA target to another. By bringing variants with different functions close together in sequence space, pairwise epistasis therefore facilitates rather than constrains the evolution of new functions.
Collapse
Affiliation(s)
- Brian PH Metzger
- Department of Ecology and Evolution, University of ChicagoChicagoUnited States
| | - Yeonwoo Park
- Program in Genetics, Genomics, and Systems Biology, University of ChicagoChicagoUnited States
| | - Tyler N Starr
- Department of Biochemistry and Molecular Biophysics, University of ChicagoChicagoUnited States
| | - Joseph W Thornton
- Department of Ecology and Evolution, University of ChicagoChicagoUnited States
- Department of Human Genetics, University of ChicagoChicagoUnited States
| |
Collapse
|
3
|
Kato H, Su L, Tanaka A, Katsu H, Ohtsubo Y, Otsuka S, Senoo K, Nagata Y. Genome evolution related to γ-hexachlorocyclohexane metabolic function in the soil microbial population. Biosci Biotechnol Biochem 2022; 86:800-809. [PMID: 35298590 DOI: 10.1093/bbb/zbac042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 03/12/2022] [Indexed: 11/12/2022]
Abstract
γ-Hexachlorocyclohexane (γ-HCH)-degrading strain, Sphingobium sp. TA15, was newly isolated from an experimental field soil from which the archetypal γ-HCH-degrading strain, S. japonicum UT26, was isolated previously. Comparison of the complete genome sequences of these 2 strains revealed that TA15 shares the same basic genome backbone with UT26, but also has the variable regions that are presumed to have changed either from UT26 or from a putative common ancestor. Organization and localization of lin genes of TA15 were different from those of UT26. It was inferred that transposition of IS6100 had played a crucial role in these genome rearrangements. The accumulation of toxic dead-end products in TA15 was lower than in UT26, suggesting that TA15 utilizes γ-HCH more effectively than UT26. These results suggested that genome evolution related to the γ-HCH metabolic function in the soil microbial population is ongoing.
Collapse
Affiliation(s)
- Hiromi Kato
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan
| | - Lijun Su
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan
| | - Ayami Tanaka
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan
| | - Honami Katsu
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan
| | - Yoshiyuki Ohtsubo
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan
| | - Shigeto Otsuka
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan
| | - Keishi Senoo
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan
| | - Yuji Nagata
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Japan
| |
Collapse
|
4
|
Yang G, Miton CM, Tokuriki N. A mechanistic view of enzyme evolution. Protein Sci 2020; 29:1724-1747. [PMID: 32557882 PMCID: PMC7380680 DOI: 10.1002/pro.3901] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/14/2020] [Accepted: 06/16/2020] [Indexed: 12/15/2022]
Abstract
New enzyme functions often evolve through the recruitment and optimization of latent promiscuous activities. How do mutations alter the molecular architecture of enzymes to enhance their activities? Can we infer general mechanisms that are common to most enzymes, or does each enzyme require a unique optimization process? The ability to predict the location and type of mutations necessary to enhance an enzyme's activity is critical to protein engineering and rational design. In this review, via the detailed examination of recent studies that have shed new light on the molecular changes underlying the optimization of enzyme function, we provide a mechanistic perspective of enzyme evolution. We first present a global survey of the prevalence of activity-enhancing mutations and their distribution within protein structures. We then delve into the molecular solutions that mediate functional optimization, specifically highlighting several common mechanisms that have been observed across multiple examples. As distinct protein sequences encounter different evolutionary bottlenecks, different mechanisms are likely to emerge along evolutionary trajectories toward improved function. Identifying the specific mechanism(s) that need to be improved upon, and tailoring our engineering efforts to each sequence, may considerably improve our chances to succeed in generating highly efficient catalysts in the future.
Collapse
Affiliation(s)
- Gloria Yang
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Charlotte M. Miton
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Nobuhiko Tokuriki
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| |
Collapse
|
5
|
Nagata Y, Kato H, Ohtsubo Y, Tsuda M. Lessons from the genomes of lindane-degrading sphingomonads. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:630-644. [PMID: 31063253 DOI: 10.1111/1758-2229.12762] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/29/2019] [Accepted: 05/02/2019] [Indexed: 05/27/2023]
Abstract
Bacterial strains capable of degrading man-made xenobiotic compounds are good materials to study bacterial evolution towards new metabolic functions. Lindane (γ-hexachlorocyclohexane, γ-HCH, or γ-BHC) is an especially good target compound for the purpose, because it is relatively recalcitrant but can be degraded by a limited range of bacterial strains. A comparison of the complete genome sequences of lindane-degrading sphingomonad strains clearly demonstrated that (i) lindane-degrading strains emerged from a number of different ancestral hosts that have recruited lin genes encoding enzymes that are able to channel lindane to central metabolites, (ii) in sphingomonads lin genes have been acquired by horizontal gene transfer mediated by different plasmids and in which IS6100 plays a role in recruitment and distribution of genes, and (iii) IS6100 plays a role in dynamic genome rearrangements providing genetic diversity to different strains and ability to evolve to other states. Lindane-degrading bacteria whose genomes change so easily and quickly are also fascinating starting materials for tracing the bacterial evolution process experimentally in a relatively short time period. As the origin of the specific lin genes remains a mystery, such genes will be useful probes for exploring the cryptic 'gene pool' available to bacteria.
Collapse
Affiliation(s)
- Yuji Nagata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai, 980-8577, Japan
| | - Hiromi Kato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai, 980-8577, Japan
| | - Yoshiyuki Ohtsubo
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai, 980-8577, Japan
| | - Masataka Tsuda
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai, 980-8577, Japan
| |
Collapse
|
6
|
Marques SM, Dunajova Z, Prokop Z, Chaloupkova R, Brezovsky J, Damborsky J. Catalytic Cycle of Haloalkane Dehalogenases Toward Unnatural Substrates Explored by Computational Modeling. J Chem Inf Model 2017; 57:1970-1989. [PMID: 28696117 DOI: 10.1021/acs.jcim.7b00070] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The anthropogenic toxic compound 1,2,3-trichloropropane is poorly degradable by natural enzymes. We have previously constructed the haloalkane dehalogenase DhaA31 by focused directed evolution ( Pavlova, M. et al. Nat. Chem. Biol. 2009 , 5 , 727 - 733 ), which is 32 times more active than the wild-type enzyme and is currently the most active variant known against that substrate. Recent evidence has shown that the structural basis responsible for the higher activity of DhaA31 was poorly understood. Here we have undertaken a comprehensive computational study of the main steps involved in the biocatalytic hydrolysis of 1,2,3-trichloropropane to decipher the structural basis for such enhancements. Using molecular dynamics and quantum mechanics approaches we have surveyed (i) the substrate binding, (ii) the formation of the reactive complex, (iii) the chemical step, and (iv) the release of the products. We showed that the binding of the substrate and its transport through the molecular tunnel to the active site is a relatively fast process. The cleavage of the carbon-halogen bond was previously identified as the rate-limiting step in the wild-type. Here we demonstrate that this step was enhanced in DhaA31 due to a significantly higher number of reactive configurations of the substrate and a decrease of the energy barrier to the SN2 reaction. C176Y and V245F were identified as the key mutations responsible for most of those improvements. The release of the alcohol product was found to be the rate-limiting step in DhaA31 primarily due to the C176Y mutation. Mutational dissection of DhaA31 and kinetic analysis of the intermediate mutants confirmed the theoretical observations. Overall, our comprehensive computational approach has unveiled mechanistic details of the catalytic cycle which will enable a balanced design of more efficient enzymes. This approach is applicable to deepen the biochemical knowledge of a large number of other systems and may contribute to robust strategies in the development of new biocatalysts.
Collapse
Affiliation(s)
- Sérgio M Marques
- Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University , Kamenice 5/A13, 625 00 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno , Pekarska 53, 656 91 Brno, Czech Republic
| | - Zuzana Dunajova
- Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University , Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Zbynek Prokop
- Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University , Kamenice 5/A13, 625 00 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno , Pekarska 53, 656 91 Brno, Czech Republic
| | - Radka Chaloupkova
- Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University , Kamenice 5/A13, 625 00 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno , Pekarska 53, 656 91 Brno, Czech Republic
| | - Jan Brezovsky
- Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University , Kamenice 5/A13, 625 00 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno , Pekarska 53, 656 91 Brno, Czech Republic
| | - Jiri Damborsky
- Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University , Kamenice 5/A13, 625 00 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno , Pekarska 53, 656 91 Brno, Czech Republic
| |
Collapse
|
7
|
Brezovsky J, Babkova P, Degtjarik O, Fortova A, Gora A, Iermak I, Rezacova P, Dvorak P, Smatanova IK, Prokop Z, Chaloupkova R, Damborsky J. Engineering a de Novo Transport Tunnel. ACS Catal 2016. [DOI: 10.1021/acscatal.6b02081] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Jan Brezovsky
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Petra Babkova
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Oksana Degtjarik
- Faculty
of Science, University of South Bohemia in Ceske Budejovice, Branisovska 1760, 37005 Ceske Budejovice, Czech Republic
- Center for Nanobiology and Structural Biology ASCR, Zamek 136, 37333 Nove Hrady, Czech Republic
| | - Andrea Fortova
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Artur Gora
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Iuliia Iermak
- Faculty
of Science, University of South Bohemia in Ceske Budejovice, Branisovska 1760, 37005 Ceske Budejovice, Czech Republic
- Center for Nanobiology and Structural Biology ASCR, Zamek 136, 37333 Nove Hrady, Czech Republic
| | - Pavlina Rezacova
- Institute of Organic Chemistry and Biochemistry ASCR, v.v.i. Flemingovo nam. 2, 166 10 Prague 6, Czech Republic
- Institute of Molecular Genetics of the ASCR, v.v.i. Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Pavel Dvorak
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Ivana Kuta Smatanova
- Faculty
of Science, University of South Bohemia in Ceske Budejovice, Branisovska 1760, 37005 Ceske Budejovice, Czech Republic
- Center for Nanobiology and Structural Biology ASCR, Zamek 136, 37333 Nove Hrady, Czech Republic
| | - Zbynek Prokop
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Radka Chaloupkova
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Jiri Damborsky
- Loschmidt
Laboratories, Department of Experimental Biology and Research Centre
for Toxic Compounds in the Environment RECETOX, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| |
Collapse
|
8
|
Tabata M, Ohhata S, Nikawadori Y, Kishida K, Sato T, Kawasumi T, Kato H, Ohtsubo Y, Tsuda M, Nagata Y. Comparison of the complete genome sequences of four γ-hexachlorocyclohexane-degrading bacterial strains: insights into the evolution of bacteria able to degrade a recalcitrant man-made pesticide. DNA Res 2016; 23:581-599. [PMID: 27581378 PMCID: PMC5144681 DOI: 10.1093/dnares/dsw041] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/09/2016] [Indexed: 11/20/2022] Open
Abstract
γ-Hexachlorocyclohexane (γ-HCH) is a recalcitrant man-made chlorinated pesticide. Here, the complete genome sequences of four γ-HCH-degrading sphingomonad strains, which are most unlikely to have been derived from one ancestral γ-HCH degrader, were compared. Together with several experimental data, we showed that (i) all the four strains carry almost identical linA to linE genes for the conversion of γ-HCH to maleylacetate (designated “specific” lin genes), (ii) considerably different genes are used for the metabolism of maleylacetate in one of the four strains, and (iii) the linKLMN genes for the putative ABC transporter necessary for γ-HCH utilization exhibit structural divergence, which reflects the phylogenetic relationship of their hosts. Replicon organization and location of the lin genes in the four genomes are significantly different with one another, and that most of the specific lin genes are located on multiple sphingomonad-unique plasmids. Copies of IS6100, the most abundant insertion sequence in the four strains, are often located in close proximity to the specific lin genes. Analysis of the footprints of target duplication upon IS6100 transposition and the experimental detection of IS6100 transposition strongly suggested that the IS6100 transposition has caused dynamic genome rearrangements and the diversification of lin-flanking regions in the four strains.
Collapse
Affiliation(s)
- Michiro Tabata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Satoshi Ohhata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Yuki Nikawadori
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Kouhei Kishida
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Takuya Sato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Toru Kawasumi
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Hiromi Kato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Yoshiyuki Ohtsubo
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Masataka Tsuda
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Yuji Nagata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| |
Collapse
|
9
|
Miton CM, Tokuriki N. How mutational epistasis impairs predictability in protein evolution and design. Protein Sci 2016; 25:1260-72. [PMID: 26757214 DOI: 10.1002/pro.2876] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/06/2016] [Accepted: 01/06/2016] [Indexed: 01/05/2023]
Abstract
There has been much debate about the extent to which mutational epistasis, that is, the dependence of the outcome of a mutation on the genetic background, constrains evolutionary trajectories. The degree of unpredictability introduced by epistasis, due to the non-additivity of functional effects, strongly hinders the strategies developed in protein design and engineering. While many studies have addressed this issue through systematic characterization of evolutionary trajectories within individual enzymes, the field lacks a consensus view on this matter. In this work, we performed a comprehensive analysis of epistasis by analyzing the mutational effects from nine adaptive trajectories toward new enzymatic functions. We quantified epistasis by comparing the effect of mutations occurring between two genetic backgrounds: the starting enzyme (for example, wild type) and the intermediate variant on which the mutation occurred during the trajectory. We found that most trajectories exhibit positive epistasis, in which the mutational effect is more beneficial when it occurs later in the evolutionary trajectory. Approximately half (49%) of functional mutations were neutral or negative on the wild-type background, but became beneficial at a later stage in the trajectory, indicating that these functional mutations were not predictable from the initial starting point. While some cases of strong epistasis were associated with direct interaction between residues, many others were caused by long-range indirect interactions between mutations. Our work highlights the prevalence of epistasis in enzyme adaptive evolution, in particular positive epistasis, and suggests the necessity of incorporating mutational epistasis in protein engineering and design to create highly efficient catalysts.
Collapse
Affiliation(s)
- Charlotte M Miton
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Nobuhiko Tokuriki
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| |
Collapse
|
10
|
Properties and biotechnological applications of natural and engineered haloalkane dehalogenases. Appl Microbiol Biotechnol 2015; 99:9865-81. [DOI: 10.1007/s00253-015-6954-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 08/19/2015] [Accepted: 08/22/2015] [Indexed: 01/01/2023]
|