[Directed evolution of D-lactonohydrolase by error prone PCR and DNA shuffling].
D-lactonohydrolase is useful in the procedure of resolution of racemic pantolactone to produce D-pantolactone, but the activity and stability under low pH of the wild type enzyme is not satisfactory enough to be applied to industrial production. The expected properties of wild type enzyme were enhanced by directed evolution. According to the formation of products and pH indicators, a screening system was designed. After three sequential error prone PCR and one round DNA shuffling followed by screening, Mut E-861, the best mutant with improved activity and stability under low pH situation was obtained. Gene analysis of the Mut E-861 mutant indicated that the mutant enzyme had A352C, G721A mutations and a silent mutation of position 1038. Moreover, the activity and stability of Mut E-861 were determined. The results showed that the activity of this mutant was 5.5-fold higher than that of wild type, and the stability under low pH was improved at no expense of D-lactonohydrolase activity. After incubated at pH 6.0 and pH 5.0 the activity of D-lactonohydrolase could be retained 75% to 50%, however, compared with 40% to 20% for wild type.
Liu
Zhi-Qiang
ZQ
Laboratory of Biocatalysis, School of Biotechnology, Southern Yangtze University, Wuxi 214036, China.
Sun
Zhi-Hao
ZH
Zheng
Pu
P
Leng
Yong
Y
Qian
Jia-Nan
JN
D002265:Carboxylic Ester Hydrolases / Q000096:biosynthesis / Q000235:genetics*; D032621:DNA Shuffling; D019020:Directed Molecular Evolution; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods; D015202:Protein Engineering; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics
D050505:Mutant Proteins; D002265:Carboxylic Ester Hydrolases; C501958:D-lactonohydrolase, Fusarium moniliforme