Further stabilization of 3-isopropylmalate dehydrogenase of an extreme thermophile, Thermus thermophilus, by a suppressor mutation method

Takashi Kotsuka, Satoshi Akanuma, Masaaki Tomuro, Akihiko Yamagishi, Tairo Oshima

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

We succeeded in further improvement of the stability of 3-isopropylmalate dehydrogenase (IPMDH) from an extreme thermophile, Thermus thermophilus, by a suppressor mutation method. We previously constructed a chimeric IPMDH consisting of portions of thermophile and mesophile enzymes. The chimeric enzyme is less thermostable than the thermophile enzyme. The gene encoding the chimeric enzyme was subjected to random mutagenesis and integrated into the genome of a leuB-deficient mutant of T. thermophilus. The transformants were screened at 76°C in minimum medium, and three independent stabilized mutants were obtained. The leuB genes from these three mutants were cloned and analyzed. The sequence analyses revealed Ala-172→Val substitution in all of the mutants. The thermal stability of the thermophile IPMDH was improved by introducing the amino acid substitution.

Original languageEnglish
Pages (from-to)723-727
Number of pages5
JournalJournal of Bacteriology
Volume178
Issue number3
DOIs
Publication statusPublished - 1996 Feb
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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