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Evolving thermostability in mutant libraries of ligninolytic oxidoreductases expressed in yeast

Eva García-Ruiz12, Diana Maté1, Antonio Ballesteros1, Angel T Martinez2 and Miguel Alcalde1*

Author Affiliations

1 Department of Biocatalysis, Institute of Catalysis, CSIC, 28049 Madrid, Spain

2 Centro de Investigaciones Biológicas, CSIC, 28040 Madrid, Spain

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Microbial Cell Factories 2010, 9:17  doi:10.1186/1475-2859-9-17

Published: 18 March 2010



In the picture of a laboratory evolution experiment, to improve the thermostability whilst maintaining the activity requires of suitable procedures to generate diversity in combination with robust high-throughput protocols. The current work describes how to achieve this goal by engineering ligninolytic oxidoreductases (a high-redox potential laccase -HRPL- and a versatile peroxidase, -VP-) functionally expressed in Saccharomyces cerevisiae.


Taking advantage of the eukaryotic machinery, complex mutant libraries were constructed by different in vivo recombination approaches and explored for improved stabilities and activities. A reliable high-throughput assay based on the analysis of T50 was employed for discovering thermostable oxidases from mutant libraries in yeast. Both VP and HRPL libraries contained variants with shifts in the T50 values. Stabilizing mutations were found at the surface of the protein establishing new interactions with the surrounding residues.


The existing tradeoff between activity and stability determined from many point mutations discovered by directed evolution and other protein engineering means can be circumvented combining different tools of in vitro evolution.