Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9121876 | FEMS Microbiology Letters | 2005 | 6 Pages |
Abstract
We constructed mutant genes of Caldococcus noboribetus isocitrate dehydrogenase containing ancestral amino acid residues that were inferred using the maximal likelihood method and a composite phylogenetic tree of isocitrate dehydrogenase and 3-isopropylmalate dehydrogenase. The mutant genes were expressed in Escherichia coli and the protein products purified. Thermostabilities, reported as the half-inactivation temperatures, for the purified enzymes were determined and compared with that of the wild-type enzyme. Four of the five mutant enzymes have greater thermal stabilities than wild-type isocitrate dehydrogenase. The results are compatible with the hyperthermophilic universal ancestor (commonote) hypothesis. Incorporation of ancestral residues into a modern-day protein sequence can be used to improve protein thermostability.
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Authors
Hisako Iwabata, Keiko Watanabe, Takatoshi Ohkuri, Shin-ichi Yokobori, Akihiko Yamagishi,