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Functional expression and stabilization of horseradish peroxidase by directed evolution in Saccharomyces cerevisiae
Author(s) -
Morawski Birgit,
Quan Sara,
Arnold Frances H.
Publication year - 2001
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.1149
Subject(s) - horseradish peroxidase , thermostability , mutagenesis , hydrogen peroxide , chemistry , mutant , directed evolution , saccharomyces cerevisiae , biochemistry , peroxidase , saturated mutagenesis , isoleucine , site directed mutagenesis , enzyme , mutation , yeast , amino acid , leucine , gene
Biotechnology applications of horseradish peroxidase (HRP) would benefit from access to tailor‐made variants with greater specific activity, lower K m for peroxide, and higher thermostability. Starting with a mutant that is functionally expressed in Saccharomyces cerevisiae, we used random mutagenesis, recombination, and screening to identify HRP‐C mutants that are more active and stable to incubation in hydrogen peroxide at 50°C. A single mutation (N175S) in the HRP active site was found to improve thermal stability. Introducing this mutation into an HRP variant evolved for higher activity yielded HRP 13A7‐N175S, whose half‐life at 60°C and pH 7.0 is three times that of wild‐type (recombinant) HRP and a commercially available HRP preparation from Sigma (St. Louis, MO). The variant is also more stable in the presence of H 2 O 2 , SDS, salts (NaCl and urea), and at different pH values. Furthermore, this variant is more active towards a variety of small organic substrates frequently used in diagnostic applications. Site‐directed mutagenesis to replace each of the four methionine residues in HRP (M83, M181, M281, M284) with isoleucine revealed no mutation that significantly increased the enzyme's stability to hydrogen peroxide. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 99–107, 2001.