Effect of Amino Acid Substitutions of Escherichia Coli $\gamma$-Glutamylcysteine Synthetase

Escherichia coli $\gamma$-Glutamylcysteine Synthetase의 아미노산 치환 효과

  • 남용석 (고려대학교 농대 농화학과) ;
  • 김중수 (고려대학교 농대 농화학과) ;
  • 곽준혁 (고려대학교 농대 농화학과) ;
  • 박영인 (고려대학교 농대 유전자공학과) ;
  • 이세영 (고려대학교 농대 농화학과)
  • Published : 1991.11.01

Abstract

Two amino acid residues ($Ala^{494}$ and $Ser^{495}$ of E. coli .gamma.-glutamylcysteine synthetase have been investigated whether they are the site of feedback inhibition by site specific mutagenesis. Single substitution of $serine^{495}$ (S495F), and double substitutions of alanine$^{494}$ and $serine^{495}$ (A494G-S495F) resulted in the inactivation of the .gamma.-glutamylcysteine synthetase activity. Substitution of $alanine^{494}$ with $glycine^{494}$ resulted in a higher level of feedback inhibition. These results suggest that $serine^{495}$ in .gamma.-glutamylcysteine synthetase is required for its catalytic acitvity and $alanine^{494}$ is presumably related to the feeback inhibition site.

Keywords

E.coli ${\gamma}$-glutamylcysteine synthetase;$alanine^{494}$;$serine^{495}$;feedback inhibition site;site-specific mutagensis