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- Title
Directed Evolution and Mutant Characterization of Nitrilase from Rhodococcus rhodochrous tg1-A6.
- Authors
Luo, Hui; Ma, Jinwei; Chang, Yanhong; Yu, Huimin; Shen, Zhongyao
- Abstract
In this paper, a molecularly directed evolution-based approach was applied to modify the nitrilase from Rhodococcus rhodochrous tg1-A6 for improving properties in catalyzing nitriles. In the process of error-prone polymerase chain reaction (PCR) with the wild-type nitrilase gene acting as the template, a library of the randomly mutated nitrilase gene was constructed. Since the pH value of catalyzing solution decreased when glycolonitrile was used as the substrate of nitrilase, a high-throughput strategy based on the color change of a pH-sensitive indicator was established for rapid screening of the mutated nitrilase. After three rounds of random mutation and screening about 5000 clones, a variant (Mut3) with 5.3-fold activity of the wild-type counterpart was obtained. Five amino acid substitutions (D27E, N97K, L246F, D108E, and S111R) were found in the variant Mut3. The properties of three mutated enzymes obtained in the three-round mutation were investigated. In the conversion of glycolonitrile, the variant (Mut2) accumulated the highest concentration of glycolic acid at 10.6 g l, a much higher value than the wild type (3.2 g l).
- Subjects
BIOLOGICAL evolution; RHODOCOCCUS rhodochrous; NITRILASES; POLYMERASE chain reaction; GENETIC mutation; GENETIC regulation of enzymes
- Publication
Applied Biochemistry & Biotechnology, 2016, Vol 178, Issue 8, p1510
- ISSN
0273-2289
- Publication type
Article
- DOI
10.1007/s12010-015-1964-9