Directed Evolution of Epoxide Hydrolase from A. radiobacter toward Higher Enantioselectivity by Error-Prone PCR and DNA Shuffling

Loo, Bert van; Spelberg, Jeffrey H. Lutje; Kingma, Jaap; Sonke, Theo; Wubbolts, Marcel; Janssen, Dick B.

doi:10.1016/j.chembiol.2004.04.019

Cited by 123 publications

(63 citation statements)

References 42 publications

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“…However, mutations closer to the catalytic core appear to have a greater effect on the selected catalytic activity (30)(31)(32)(33). These residues for mutagenesis may be selected through a random, rational or combined evolutionary approach.…”

Section: Discussionmentioning

confidence: 99%

Conversion of a Cyclodextrin Glucanotransferase into an α-Amylase: Assessment of Directed Evolution Strategies

2007

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Glycoside hydrolase family 13 (GH13) members have evolved to possess various distinct reaction specificities despite the overall structural similarity. In this study we investigated the evolutionary input required to effeciently interchange these specificities and also compared the effectiveness of laboratory evolution techniques applied, i.e., error-prone PCR and saturation mutagenesis. Conversion of our model enzyme, cyclodextrin glucanotransferase (CGTase), into an R-amylase like hydrolytic enzyme by saturation mutagenesis close to the catalytic core yielded a triple mutant (A231V/F260W/F184Q) with the highest hydrolytic rate ever recorded for a CGTase, similar to that of a highly active R-amylase, while cyclodextrin production was virtually abolished. Screening of a much larger, error-prone PCR generated library yielded far less effective mutants. Our results demonstrate that it requires only three mutations to change CGTase reaction specificity into that of another GH13 enzyme. This suggests that GH13 members may have diversified by introduction of a limited number of mutations to the common ancestor, and that interconversion of reaction specificites may prove easier than previously thought.

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Section: Discussionmentioning

confidence: 99%

Conversion of a Cyclodextrin Glucanotransferase into an α-Amylase: Assessment of Directed Evolution Strategies

2007

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“…In a recent comprehensive study, Aaron et al (12) demonstrated that the evolution of higher activity toward poor substrates did not impair the parental catalytic activity, and, therefore, the evolved enzymes exhibited greater promiscuity. Enzymes evolved for higher substrate enantioselectivity often exhibit lower specific activities toward their new substrates relative to their respective parental enzymes (13)(14)(15). Similarly, the evolution of highly active variants of aspartate aminotransferases capable of accepting branched or aromatic amino acid substrates was accompanied by a relaxation of the substrate selectivity (16,17).…”

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confidence: 99%

“…Numerous structure-guided and directed evolution strategies have been used in search of enzyme variants that exhibit high catalytic rates with poor or inactive substrates of the parental enzyme (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). As impressive as these successes have been, the engineering of enzymes that exhibit turnover rates and selectivities with new substrates comparable to their natural counterparts has proven quite a challenge, especially when considering those enzymes for which a genetic selection strategy is not possible.…”

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confidence: 99%

Engineering of protease variants exhibiting high catalytic activity and exquisite substrate selectivity

Varadarajan

Gam

Olsen

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

138

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The exquisite selectivity and catalytic activity of enzymes have been shaped by the effects of positive and negative selection pressure during the course of evolution. In contrast, enzyme variants engineered by using in vitro screening techniques to accept novel substrates typically display a higher degree of catalytic promiscuity and lower total turnover in comparison with their natural counterparts. Using bacterial display and multiparameter flow cytometry, we have developed a novel methodology for emulating positive and negative selective pressure in vitro for the isolation of enzyme variants with reactivity for desired novel substrates, while simultaneously excluding those with reactivity toward undesired substrates. Screening of a large library of random mutants of the Escherichia coli endopeptidase OmpT led to the isolation of an enzyme variant, 1.3.19, that cleaved an Ala-Arg peptide bond instead of the Arg-Arg bond preferred by the WT enzyme. Variant 1.3.19 exhibited greater than three million-fold selectivity (-Ala-Arg-͞-Arg-Arg-) and a catalytic efficiency for AlaArg cleavage that is the same as that displayed by the parent for the preferred substrate, Arg-Arg. A single amino acid Ser223Arg substitution was shown to recapitulate completely the unique catalytic properties of the 1.3.19 variant. These results can be explained by proposing that this mutation acts to ''swap'' the P 1 Arg side chain normally found in WT substrate peptides with the 223Arg side chain in the S 1 subsite of OmpT.engineering ͉ flow cytometry T he reprogramming of enzyme catalytic activity and selectivity is a central issue in protein biochemistry and biotechnology. Numerous structure-guided and directed evolution strategies have been used in search of enzyme variants that exhibit high catalytic rates with poor or inactive substrates of the parental enzyme (1-19). As impressive as these successes have been, the engineering of enzymes that exhibit turnover rates and selectivities with new substrates comparable to their natural counterparts has proven quite a challenge, especially when considering those enzymes for which a genetic selection strategy is not possible.In particular, enzymes engineered through laboratory evolution involving in vitro catalytic assays have often been found lacking, either with respect to turnover rates or selectivity, relative to catalyst-substrate pairs isolated from natural sources. As a typical example, an extensive directed evolution program led to the isolation of Escherichia coli ␤-glucuronidase variants with significant ␤-galactosidase (10) or xylanosidase (11) activities, but nonetheless even the best clones exhibited k cat ͞K m values Ͼ1,000 times lower than those of naturally occurring enzymes such as the E. coli ␤-galactosidase or the Thermoanaerobacterium saccharolyticum ␤-xylosidase.This trend appears to be general. In a recent comprehensive study, Aaron et al. (12) demonstrated that the evolution of higher activity toward poor substrates did not impair the parental catalytic activity, and,...

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confidence: 99%

“…The potential for biocatalytic application of epoxide hydrolases was significantly increased with the discovery of microbial epoxide hydrolases (41), which are easier to produce in large quantities. The cloning and overexpression of several enantioselective epoxide hydrolases, e.g., from Agrobacterium radiobacter (35), Aspergillus niger (3), and potato plants (40), not only facilitated large-scale production of these enzymes but also made it possible to improve their biocatalytic properties by site-directed or random mutagenesis (34,36,43).Since many microbial genome sequences are available in the public domain, it is useful to screen these databases for genes that might encode new enzymes with interesting properties.Novel epoxide hydrolases can be identified by performing a BLAST search of the genomic databases, using amino acid sequences of known epoxide hydrolases as queries. This approach will result in putative epoxide hydrolases but also in amino acid sequences from structurally and mechanistically related enzymes, such as esterases and dehalogenases (33), which can be filtered out using conserved epoxide hydrolase sequence motifs that define the active site (Fig.…”

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confidence: 99%

Diversity and Biocatalytic Potential of Epoxide Hydrolases Identified by Genome Analysis

Loo

Kingma

Arand

et al. 2006

Appl Environ Microbiol

Self Cite

109

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Epoxide hydrolases play an important role in the biodegradation of organic compounds and are potentially useful in enantioselective biocatalysis. An analysis of various genomic databases revealed that about 20% of sequenced organisms contain one or more putative epoxide hydrolase genes. They were found in all domains of life, and many fungi and actinobacteria contain several putative epoxide hydrolase-encoding genes. Multiple sequence alignments of epoxide hydrolases with other known and putative ␣/␤-hydrolase fold enzymes that possess a nucleophilic aspartate revealed that these enzymes can be classified into eight phylogenetic groups that all contain putative epoxide hydrolases. To determine their catalytic activities, 10 putative bacterial epoxide hydrolase genes and 2 known bacterial epoxide hydrolase genes were cloned and overexpressed in Escherichia coli. The production of active enzyme was strongly improved by fusion to the maltose binding protein (MalE), which prevented inclusion body formation and facilitated protein purification. Eight of the 12 fusion proteins were active toward one or more of the 21 epoxides that were tested, and they converted both terminal and nonterminal epoxides. Four of the new epoxide hydrolases showed an uncommon enantiopreference for meso-epoxides and/or terminal aromatic epoxides, which made them suitable for the production of enantiopure (S,S)-diols and (R)-epoxides. The results show that the expression of epoxide hydrolase genes that are detected by analyses of genomic databases is a useful strategy for obtaining new biocatalysts.Enantiopure epoxides and vicinal diols are valuable intermediates in the synthesis of a number of pharmaceutical compounds. Epoxide hydrolases (EC 3.3.2.3) catalyze the conversion of epoxides to the corresponding diols. If they are enantioselective, they can be used to produce enantiopure epoxides by means of kinetic resolution (5). In the past, when only epoxide hydrolases from mammalian sources were known (12), the use of epoxide hydrolases in biocatalysis was hampered by their poor availability and insufficient catalytic performance, such as a low turnover rate or poor enantioselectivity. The potential for biocatalytic application of epoxide hydrolases was significantly increased with the discovery of microbial epoxide hydrolases (41), which are easier to produce in large quantities. The cloning and overexpression of several enantioselective epoxide hydrolases, e.g., from Agrobacterium radiobacter (35), Aspergillus niger (3), and potato plants (40), not only facilitated large-scale production of these enzymes but also made it possible to improve their biocatalytic properties by site-directed or random mutagenesis (34,36,43).Since many microbial genome sequences are available in the public domain, it is useful to screen these databases for genes that might encode new enzymes with interesting properties.Novel epoxide hydrolases can be identified by performing a BLAST search of the genomic databases, using amino acid sequences of known epoxide hyd...

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Directed Evolution of Epoxide Hydrolase from A. radiobacter toward Higher Enantioselectivity by Error-Prone PCR and DNA Shuffling

Cited by 123 publications

References 42 publications

Conversion of a Cyclodextrin Glucanotransferase into an α-Amylase: Assessment of Directed Evolution Strategies

Conversion of a Cyclodextrin Glucanotransferase into an α-Amylase: Assessment of Directed Evolution Strategies

Engineering of protease variants exhibiting high catalytic activity and exquisite substrate selectivity

Diversity and Biocatalytic Potential of Epoxide Hydrolases Identified by Genome Analysis

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