The crystal structures of mutated 3-isopropylmalate dehydrogenase from Thermus thermophilus HB8 and their relationship to the thermostability of the enzyme

Hideaki Moriyama, Ko Onodera, Masahiro Sakurai, Nobuo Tanaka, Hiromi Kirino, Tairo Oshima, Yukiteru Katsubet

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The structures of two mutant forms (G240A and L246E/V249M) of 3-isopropylmalate dehydrogenase from Thermus thermophilus HB8 were studied by X-ray crystallography. In the case of G240A, the replacement of glycine by alanine at residue 240 was expected to decrease the thermostability as a result of abnormal contacts between the methyl group of alanine and the peptide chain. However, the normal van der Waals' contacts were achieved owing to a shift in a bundle of β-strands that yielded a vacant space for the alanine residue. The extended hydrogen bonds within the β-sheet are the major reason for the decreased thermostability of G240A. The mutations in L246E/V249M are located in an α-helix region which is involved in subunit-subunit contact via hydrophobic interaction. Loosening of the subunit-subunit contact owing to ionic repulsion was the major cause of the lower heat stability of L246E/V249M.

Original languageEnglish (US)
Pages (from-to)408-413
Number of pages6
JournalJournal of Biochemistry
Volume117
Issue number2
DOIs
StatePublished - Feb 1995

Keywords

  • 3-isopropylmalate dehydrogenase
  • Crystal structures
  • Mutation
  • Thermo stability
  • Thermus thermophilus

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

Fingerprint Dive into the research topics of 'The crystal structures of mutated 3-isopropylmalate dehydrogenase from Thermus thermophilus HB8 and their relationship to the thermostability of the enzyme'. Together they form a unique fingerprint.

Cite this