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1.
Chinese Journal of Biotechnology ; (12): 2197-2210, 2021.
Article in Chinese | WPRIM | ID: wpr-887789

ABSTRACT

Enzymes and cell factories are the core of industrial biotechnology. They play important roles in various fields such as medicine, chemical industry, food, agriculture, and energy. Usually, natural enzymes and cells need to be engineered to improve the catalytic efficiency, stability and enantioselectivity. Directed evolution makes it possible to rapidly improve the properties of enzymes and cell factories. Sensitive and reliable high-throughput screening approaches are the key for successful and efficient engineering of enzymes and cell factories. In this review, we first summarize the advantages and disadvantages of different screening methods and signal generation strategies as well as their application scope; we then describe the latest advances of ultra-high throughput screening technology applied in the directed evolution of enzymes and cell factories in the past three years. On this basis, we discuss the limiting factors that need to be further improved for high-throughput screening systems and forecast the future development trends of high-throughput screening methods, hoping that researchers in various fields including biotechnology and instrument development can cooperate closely to enhance the reliability and applicability of the high-throughput screening techniques.


Subject(s)
Biotechnology , Directed Molecular Evolution , Enzymes , High-Throughput Screening Assays , Reproducibility of Results
2.
Chinese Journal of Biotechnology ; (12): 486-499, 2021.
Article in Chinese | WPRIM | ID: wpr-878577

ABSTRACT

Laboratory evolution is an important approach to improve the performance of microorganisms. In the past decades, the methods for laboratory evolution have developed rapidly and applied widely. However, the commonly used evolution strategies for strains or specific proteins cannot achieve continuous mutation, and require multiple rounds of operation, therefore they are considered as a labor intensive process. The development of mutation and screening technologies have facilitated the development of continuous evolution in vivo and greatly improved the efficiency of laboratory evolution. The continuous in vivo evolution achieves in vivo mutation, perfectly combining mutation with screening to evolve a specific phenotype with minimal human intervention. This review summarizes the recent advances of in vivo continuous evolution technologies for either genome-scale mutation or evolution of specific proteins. The principles of these technologies and their applications are introduced. On this basis, the advantages and limitations of these technologies are discussed. We also give a perspective of future development of continuous in vivo evolution.


Subject(s)
Directed Molecular Evolution , Humans , Mutation , Phenotype , Proteins
3.
Chinese Journal of Biotechnology ; (12): 163-177, 2021.
Article in Chinese | WPRIM | ID: wpr-878551

ABSTRACT

Directed evolution is a cyclic process that alternates between constructing different genes and screening functional gene variants. It has been widely used in optimization and analysis of DNA sequence, gene function and protein structure. It includes random gene libraries construction, gene expression in suitable hosts and mutant libraries screening. The key to construct gene library is the storage capacity and mutation diversity, to screen is high sensitivity and high throughput. This review discusses the latest advances in directed evolution. These new technologies greatly accelerate and simplify the traditional directional evolution process and promote the development of directed evolution.


Subject(s)
Base Sequence , Directed Molecular Evolution , Gene Library , Mutation , Proteins/genetics
4.
Chinese Journal of Biotechnology ; (12): 1843-1856, 2019.
Article in Chinese | WPRIM | ID: wpr-771748

ABSTRACT

By constructing mutant libraries and utilizing high-throughput screening methods, directed evolution has emerged as the most popular strategy for protein design nowadays. In the past decade, taking advantages of computer performance and algorithms, computer-assisted protein design has rapidly developed and become a powerful method of protein engineering. Based on the simulation of protein structure and calculation of energy function, computational design can alter the substrate specificity and improve the thermostability of enzymes, as well as de novo design of artificial enzymes with expected functions. Recently, machine learning and other artificial intelligence technologies have also been applied to computational protein engineering, resulting in a series of remarkable applications. Along the lines of protein engineering, this paper reviews the progress and applications of computer-assisted protein design, and current trends and outlooks of the development.


Subject(s)
Directed Molecular Evolution , High-Throughput Screening Assays , Protein Engineering , Proteins , Chemistry , Genetics , Metabolism , Substrate Specificity
5.
Protein & Cell ; (12): 552-562, 2014.
Article in English | WPRIM | ID: wpr-757471

ABSTRACT

Photosynthetic CO(2) fixation is the ultimate source of organic carbon on earth and thus is essential for crop production and carbon sequestration. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the first step of photosynthetic CO(2) fixation. However, the extreme low carboxylation efficiency of Rubisco makes it the most attractive target for improving photosynthetic efficiency. Extensive studies have focused on re-engineering a more efficient enzyme, but the effort has been impeded by the limited understanding of its structure-function relationships and the lack of an efficient selection system towards its activity. To address the unsuccessful molecular engineering of Rubisco, we developed an Escherichia coli-based activity-directed selection system which links the growth of host cell solely to the Rubisco activity therein. A Synechococcus sp. PCC7002 Rubisco mutant with E49V and D82G substitutions in the small subunit was selected from a total of 15,000 mutants by one round of evolution. This mutant showed an 85% increase in specific carboxylation activity and a 45% improvement in catalytic efficiency towards CO(2). The small-subunit E49V mutation was speculated to influence holoenzyme catalysis through interaction with the large-subunit Q225. This interaction is conserved among various Rubisco from higher plants and Chlamydomonas reinhardtii. Knowledge of these might provide clues for engineering Rubisco from higher plants, with the potential of increasing the crop yield.


Subject(s)
Amino Acid Substitution , Bacterial Proteins , Chemistry , Genetics , Carbon Dioxide , Chemistry , Directed Molecular Evolution , Escherichia coli , Ribulose-Bisphosphate Carboxylase , Chemistry , Genetics , Synechococcus
6.
Egyptian Journal of Medical Human Genetics [The]. 2014; 15 (1): 1-5
in English | IMEMR | ID: emr-154341

ABSTRACT

The concept of biological evolution has long been accepted as a palatable theory aiming at explaining how life began and how creatures diverged so widely along the life span of the earth. Meticulous analysis and criticism of the different postulations of this concept, however, reveals that evolution is an illogic concept based on theoretical hypotheses that can never be tested. Creation, on the other hand, represents the other side of the coin, and up till now debates confronting creation versus evolution are still occupying much interest of atheist as well as of believer biologists. The motive for accepting the concept of evolution by most biologists, stems solely from their atheism and their saying that creation can neither be experimented nor validated, the same criticism directed against their assumptions regarding the basic aspects of evolution. This article, through analysis, criticism and reevaluation of some relevant genetic considerations that have long been traditionally considered as observations in support of the concept of evolution, viz. genetic memory and evolutionary variations, genomic adaptations to stress and evolution, comparative genomics and natural versus targeted selection, tries to elucidate and reveal some insensible assumptions embodied within the core ideas of evolution that stand in direct controversy with many well-known facts regarding the structure, function and behavior of living matter. Natural selection might be observed in nature but not in life. The concept of biological evolution is an illogic and insensible hypothesis since it stands in direct contradiction with our current knowledge regarding the behavior as well as the structural and functional characteristics of the human genome and human proteome. Additionally, almost all basic postulations of this concept can neither be tested nor imitated for experimentation, which is a prerequisite for acceptance and validation of any scientific hypotheses


Subject(s)
Directed Molecular Evolution , Genome, Human/genetics
7.
Chinese Journal of Biotechnology ; (12): 1753-1764, 2013.
Article in Chinese | WPRIM | ID: wpr-242456

ABSTRACT

Directed evolution was conducted to improve the thermostability of lipase from Rhizopus chinensis CCTCC M201021. Mutations were introduced by two rounds of error-prone PCR and mutant lipase was selected by fast-blue RR top agar screening. Two positive variants were selected in the first-round and four in the second-round screening process. Ep2-4 was proved as the most thermostable lipase and its DNA sequencing revealed three amino acid substitutions: A129S, P168L and V329A. Compared with the parent, its half-life at 60 degrees C was 5.4- times longer and T50 was 7.8 degrees higher. Purified lipase of Ep2-4 was characterized and the result shows that its thermostability improved without compromising enzyme activity. According to the mimicked protein structure, mutation A129S formed a hydrogen bond with Gln133 and improved the thermostability by increasing the hydrophilicity and polarity of protein; mutation P168L by forming a hydrophobic bond with the nearby Leu164.


Subject(s)
Cloning, Molecular , Directed Molecular Evolution , Methods , Enzyme Stability , Genetics , Hot Temperature , Industrial Microbiology , Lipase , Chemistry , Genetics , Mutation , Pichia , Genetics , Metabolism , Polymerase Chain Reaction , Methods , Protein Engineering , Methods , Rhizopus
8.
Chinese Journal of Biotechnology ; (12): 422-433, 2013.
Article in Chinese | WPRIM | ID: wpr-233233

ABSTRACT

Molecular engineering of cellulases can improve enzymatic activity and efficiency. Recently, the Carbohydrate-Active enZYmes Database (CAZy), including glycoside hydrolase (GH) families, has been established with the development of Omics and structural measurement technologies. Molecular engineering based on GH families can obviously decrease the probing space of target sequences and structures, and increase the odds of experimental success. Besides, the study of cellulase active-site architecture paves the way toward the explanation of catalytic mechanism. This review focuses on the main GH families and the latest progresses in molecular engineering of catalytic domain. Based on the combination of analysis of a large amount of data in the same GH family and their conservative active-site architecture information, rational design will be an important direction for molecular engineering and promote the rapid development of the conversion of biomass.


Subject(s)
Catalytic Domain , Genetics , Cellulase , Chemistry , Genetics , Directed Molecular Evolution , Methods , Evolution, Molecular , Glycoside Hydrolases , Chemistry , Genetics , Protein Engineering , Methods
9.
Biol. Res ; 46(4): 395-405, 2013. ilus, tab
Article in English | LILACS | ID: lil-700402

ABSTRACT

Enzymes have been long used in man-made biochemical processes, from brewing and fermentation to current industrial production of fine chemicals. The ever-growing demand for enzymes in increasingly specific applications requires tailoring naturally occurring enzymes to the non-natural conditions found in industrial processes. Relationships between enzyme sequence, structure and activity are far from understood, thus hindering the capacity to design tailored biocatalysts. In the field of protein engineering, directed enzyme evolution is a powerful algorithm to generate and identify novel and improved enzymes through iterative rounds of mutagenesis and screening applying a specific evolutive pressure. In practice, critical checkpoints in directed evolution are: selection of the starting point, generation of the mutant library, development of the screening assay and analysis of the output of the screening campaign. Each step in directed evolution can be performed using conceptually and technically different approaches, all having inherent advantages and challenges. In this article, we present and discuss in a general overview, challenges of designing and performing a directed enzyme evolution campaign, current advances in methods, as well as highlighting some examples of its applications in industrially relevant enzymes.


Subject(s)
Biotechnology/methods , Directed Molecular Evolution/methods , Enzymes/metabolism , Protein Engineering/methods , Biocatalysis , Enzymes/chemistry , Enzymes/genetics , Mutagenesis
11.
Chinese Journal of Biotechnology ; (12): 781-788, 2012.
Article in Chinese | WPRIM | ID: wpr-342442

ABSTRACT

As an efficient and promising protein engineering strategy, directed evolution includes the construction of mutant libraries and screening of desirable mutants. A rapid and high-throughput screening method has played a critical role in the successful application of directed evolution strategy. We reviewed several high-throughput screening tools which have great potential to be applied in directed evolution. The development of powerful high-throughput screening tools will make great contributions to the advancement of protein engineering.


Subject(s)
Directed Molecular Evolution , Methods , High-Throughput Screening Assays , Methods , Mutagenesis, Site-Directed , Methods , Mutant Proteins , Genetics , Protein Engineering , Methods
12.
Article in English | WPRIM | ID: wpr-211718

ABSTRACT

Epidermal growth factor receptor (EGFR) is an attractive target for tumor therapy because it is overexpressed in the majority of solid tumors and the increase in receptor expression levels has been linked with a poor clinical prognosis. Also it is well established that blocking the interaction of EGFR and the growth factors could lead to the arrest of tumor growth and possibly result in tumor cell death. A13 is a murine monoclonal antibody (mAb) that specifically binds to various sets of EGFR-expressing tumor cells and inhibits EGF-induced EGFR phosphorylation. We isolated human immunoglobulin genes by guided selection based on the mAb A13. Four different human single chain Fvs (scFvs) were isolated from from hybrid scFv libraries containing a human VH repertoire with the VL of mAb A13 and a human VL repertoire with the VH of mAb A13. All the 4 scFvs bound to EGFR-expressing A431 cells. One scFv (SC414) with the highest affinity was converted to IgG1 (ER414). The ER414 exhibited ~17 fold lower affinity compared to the A13 mAb. In addition the ER414 inhibited an EGF-induced tyrosine phosphorylation of EGFR with much lower efficacy compared to the A13 mAb and Cetuximab (Merck KgaA, Germany). We identified that the epitope of A13 mAb is retained in ER414. This approach will provide an efficient way of converting a murine mAb to a human mAb.


Subject(s)
Animals , Antibodies, Monoclonal, Humanized/genetics , Antibody Affinity , Cell Line, Tumor , Directed Molecular Evolution/methods , Epitope Mapping , Epitopes/genetics , Humans , Immunotherapy , Mice , Neoplasms/therapy , Phosphorylation/drug effects , Protein Binding , ErbB Receptors/antagonists & inhibitors , Selection, Genetic , Single-Chain Antibodies/genetics
13.
Chinese Journal of Biotechnology ; (12): 1100-1108, 2011.
Article in Chinese | WPRIM | ID: wpr-324498

ABSTRACT

The experiment was conducted by directed evolution strategy (error-prone PCR) to improve the activity of aflatoxin detoxifzyme with the high-throughput horse radish peroxidas and recessive brilliant green (HRP-RBG) screening system. We built up a mutant library to the order of 10(4). Two rounds of EP-PCR and HRP-RBG screening were used to obtain three optimum mutant strains A1773, A1476 and A2863. We found that mutant A1773 had upper temperature tolerance of 70 degrees C and that its enzyme activity was 6.5 times higher than that of the parent strain. Mutant strains A1476 worked well at pH 4.0 and its enzyme activity was 21 times higher than that of the parent strain. Mutant A2863 worked well at pH 4.0 and pH 7.5, and its enzyme activity was 12.6 times higher than that of the parent strain. With DNA sequencing we found that mutant A1773 revealed two amino acid substitutions, Glu127Lys and Gln613Arg. Mutant A1476 revealed four amino acid substitutions: Ser46Pro, Lys221Gln, Ile307Leu and Asn471lle. Mutant A2863 revealed four amino acid substitutions: Gly73Ser, Ile307Leu, Va1596Ala and Gln613Arg. The results provided a useful illustration for the deep understanding of the relationship between the function and structure of aflatoxin detoxifzyme.


Subject(s)
Aflatoxin B1 , Chemistry , Amino Acid Substitution , Directed Molecular Evolution , Enzyme Activation , Enzyme Stability , Multienzyme Complexes , Genetics , Metabolism , Mutant Proteins , Genetics , Metabolism , Point Mutation , Polymerase Chain Reaction , Methods , Protein Engineering
14.
Chinese Journal of Biotechnology ; (12): 1797-1804, 2011.
Article in Chinese | WPRIM | ID: wpr-304519

ABSTRACT

Directed evolution was used to improve the performance of beta-1,3-1,4-glucanase (designated as PtLicl6A) from Paecilomyces thermophila J18 under acidic condition. A mutant library was constructed by error-prone PCR and DNA shuffling, and positive clones were screened by Congo red staining. More than 1 500 mutants were selected. One mutant (PtLic16AM1) exhibited an optimal activity at pH 5.5, while the optimal pH of the wild-type enzyme was 7.0. The mutant PtLic16AM1 kept the high specific activity and thermotolerence of the wild-type enzyme. Sequence analysis revealed that the mutant enzyme has four sense substitutions which caused four amino acid substitutions - namely T58S, Y110N, G195E and D221G.. Homology modeling showed that among the four amino acid substitutions, Y110N was near the active site of the enzyme, while the other three was distant. T58S and G195E may play key roles in the change of optimal pH. This study provided a new perspective of obtaining applicable 3-1,3-1,4-glucanase for industrial use.


Subject(s)
Catalysis , Directed Molecular Evolution , Methods , Endo-1,3(4)-beta-Glucanase , Genetics , Metabolism , Enzyme Stability , Hot Temperature , Hydrogen-Ion Concentration , Mutant Proteins , Metabolism , Mutation , Paecilomyces , Classification , Genetics , Protein Engineering , Methods
16.
Chinese Journal of Biotechnology ; (12): 159-164, 2010.
Article in Chinese | WPRIM | ID: wpr-336248

ABSTRACT

Directed evolution of transcription factors can be employed to effectively improve the phenotypes which are controlled by multiple genetic loci. In this study, we used error-prone PCR for the directed evolution of SPT3, which is the component of yeast Spt-Ada-Gcn5-acetyltransferase (SAGA) complex responsible for the transcription of stress-related genes, and studied its effect on the improvement of ethanol tolerance. Mutant library was constructed by ligating the error-prone PCR products with a modified pYES2.0 plasmid, and the expression plasmids were subsequently transformed to yeast industrial strain Saccharomyces cerevisiae 4126. One mutant strain M25 showing superior growth in presence of 10% ethanol was selected. M25 produced 11.7% more ethanol than the control strain harboring the empty vector when 125 g/L glucose was used as substrate. This study revealed that SPT3 is an important transcription factor for the metabolic engineering of yeast ethanol tolerance.


Subject(s)
Directed Molecular Evolution , Methods , Drug Resistance, Fungal , Drug Tolerance , Ethanol , Metabolism , Pharmacology , Industrial Microbiology , Methods , Saccharomyces cerevisiae , Genetics , Metabolism , Saccharomyces cerevisiae Proteins , Genetics , Trans-Activators , Genetics , Transcription Factors , Genetics
17.
Chinese Journal of Biotechnology ; (12): 1293-1301, 2010.
Article in Chinese | WPRIM | ID: wpr-351593

ABSTRACT

In vitro evolution methods are often used to modify protein with improved characteristics. We developed a directed evolution protocol to enhance the thermostability of the beta-1,3-1,4-glucanase. The thermostability of the enzyme was significantly improved after two rounds of directed evolution. Three variants with higher thermostability were obtained. The mutant enzymes were further analyzed by their melting temperature, halftime and kinetic parameters. Comparing to intact enzyme, the T50 of mutant enzymes 2-JF-01, 2-JF-02 and 2-JF-03 were increased by 2.2 degrees C, 5.5 degrees C and 3.5 degrees C, respectively, the halftime (t1/2, 60 degrees C) of mutant enzymes 2-JF-01, 2-JF-02 and 2-JF-03 were shortened by 4,13 and 17 min, respectively, the V(max) of mutant enzymes were decreased by 8.3%, 2.6% and 10.6%, respectively, while K(m) of mutant enzymes were nearly unchanged. Sequence analysis revealed seven single amino acid mutant happened among three mutant enzymes, such as 2-JF-01 (N36S, G213R), 2-JF-02 (C86R, S115I, N150G) and 2-JF-03 (E156V, K105R). Homology-modeling showed that five of seven substituted amino acids were located on the surface of or in hole of protein. 42.8% of substituted amino acids were arginine, which indicated that arginine may play a role in the improvement of the thermostability of the beta-1,3-1,4-glucanase.This study provide some intresting results of the structural basis of the thermostability of beta-1,3-1,4-glucanase,and provide some new point of view in modifying enzyme for future industrial use.


Subject(s)
Amino Acid Sequence , Bacillus , Directed Molecular Evolution , Endo-1,3(4)-beta-Glucanase , Chemistry , Genetics , Enzyme Stability , Hot Temperature , Molecular Sequence Data , Recombinant Fusion Proteins , Chemistry , Genetics
18.
Chinese Journal of Biotechnology ; (12): 1892-1899, 2009.
Article in Chinese | WPRIM | ID: wpr-336291

ABSTRACT

Directed evolution strategy (error-prone PCR) was conducted to improve the activity of lipase from Rhizopus chinensis CCTCC M201021. Through two rounds of ep-PCR and pNPP top agar screening, two optimum mutant strains 1-11 and 2-28 were obtained with 2 and 4 fold of enzyme activity higher than that of parent strain, respectively. DNA sequencing of mutant lipase 2-28 revealed four amino acid substitutions: A129S, K161R, A230T, K322R. According to the simulated protein structure of Rhizopus chinensis lipase, A129S, K161R, A230T were located on the surface of the protein. A230T substitution improved the stability of the alpha-helix loop. K322R, near the catalytic center of lipase, located at a loop, formed a salt-bridge with a nearby aspartic acid (negative charged). Electrostatic force pulled the loop to the opposite direction of the substrate channel and made it easier for substrate to enter the lipase catalytic domain. Purified lipase was characterized and the result showed that Km of 2-28 lipase decreased by 10% compared with Km of the parent lipase, and Kcat was 2.75 fold improved than that of the original lipase.


Subject(s)
Directed Molecular Evolution , Lipase , Chemistry , Genetics , Point Mutation , Protein Engineering , Rhizopus , Genetics
19.
Chinese Journal of Biotechnology ; (12): 1900-1906, 2009.
Article in Chinese | WPRIM | ID: wpr-336290

ABSTRACT

Firstly, We used error-prone PCR to induce mutations on Armillariella tabescens MAN47 beta-mannanase gene, Secondly, we cloned the mutated fragments into secreted expression vector pYCalpha, Then the recombinant plasmids were transformed into Saccharomyces cerevisiae BJ5465 after amplified and extracted in DH5alpha cells. Through three cycles of error-prone PCR we built a mutant database, Then we screened one optimum (named M262) from about 104 mutants. The evoluted MAN47 beta-mannanase displayed both higher thermal stability and activity than wide type. The evoluted enzyme M262 retained high activity after treatment at 80 degrees C for 30 min, whereas, the wild type nearly lost activity under this condition. Meanwhile, the activity of M262 can reach to 25 U/mL, which is 4.3 times as wide type under optimum temperature. In addition, pH stability and pH range of evoluted enzyme M262 were both improved compared with wild-type enzyme. The optimum pH was estimated to be similar to that of wild-type enzyme. The sequence comparison illustrated that there were three nucleotide substitutions (T343A/C827T/T1139C) which carried corresponding amino acid changes (Ser115Thr/Thr276Met/Val380Ala). According to homologous modeling by SWISS-MODEL Repository, three mutated amino acids located at the sixth amino acid of the fourth beta-sheet, the first amino acid of the sixth alpha-helix, the turn between the tenth and eleventh beta-sheet, respectively.


Subject(s)
Armillaria , Classification , Genetics , Directed Molecular Evolution , Enzyme Stability , Escherichia coli , Genetics , Hot Temperature , Mutant Proteins , Genetics , Metabolism , Point Mutation , Polymerase Chain Reaction , Methods , Protein Engineering , Recombinant Proteins , Genetics , Metabolism , Saccharomyces cerevisiae , Genetics , beta-Mannosidase , Chemistry , Genetics , Metabolism
20.
Chinese Journal of Biotechnology ; (12): 1312-1315, 2009.
Article in Chinese | WPRIM | ID: wpr-296923

ABSTRACT

Directed evolution, which is also called molecular evolution, or artificial evolution, combines random mutagenesis and directed selection. In previous studies, it has been extensively applied for the improvement of enzyme catalytic properties and stability, as well as the expanding of substrate specificity. In recent years, directed evolution was also employed in metabolic engineering of promoters for improving their strength and function, and the engineering of global transcription machinery. These techniques contribute to breeding more tolerant strains against environmental stress, as well as strains with improved fermentation efficiency. In this article, we reviewed the applications of directed evolution in the metabolic engineering of promoters and global transcription machinery. These techniques enabled fine-tuning of gene expression and simultaneous alternation of multiple gene transcription inside the cells, and thus are powerful new tools for metabolic engineering.


Subject(s)
Directed Molecular Evolution , Genetic Engineering , Industrial Microbiology , Methods , Metabolism , Promoter Regions, Genetic , Genetics , Saccharomyces cerevisiae , Genetics , Transcription, Genetic , Genetics
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