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Thermostabilization of cellulosomal endoglucanase EngB from Clostridium cellulovorans by in vitro DNA recombination with non‐cellulosomal endoglucanase EngD
Author(s) -
Murashima Koichiro,
Kosugi Akihiko,
Doi Roy H.
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.03049.x
Subject(s) - thermostability , cellulosome , cellulase , biology , mutant , biochemistry , enzyme , microbiology and biotechnology , clostridium thermocellum , gene
Summary Enhancement of enzyme thermostability by protein engineering gives us information about the thermostabilization mechanism as well as advantages for industrial use of enzymes. In this study, we enhanced the thermostability of endoglucanase EngB, one component of the cellulase complex (cellulosome) from Clostridium cellulovorans , by the directed evolution technique. The library was constructed by in vitro recombination of the genes for EngB and non‐cellulosomal cellulase EngD, based on the fact that the catalytic domains of both cellulases were highly homologous. To obtain thermostable clones without loss of activity, the library was screened by a com‐bination of activity and thermostability screening. We obtained three mutants out of 8000 selected clones that showed significantly higher thermostability than those of EngB and EngD without compromising their endoglucanase activities. One of the mutants possessed a sevenfold higher thermostability than EngB. The possible mechanisms of thermostabilization are discussed.