Proteomic response analysis of a threonine-overproducing mutant of Escherichia coli

Yang Hoon Kim, Jin Seung Park, Jae Yong Cho, Kwang Myung Cho, Young Hoon Park, Jeewon Lee

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The proteomic response of a threonine-overproducing mutant of Escherichia coli was quantitatively analysed by two-dimensional electrophoresis. Evidently, 12 metabolic enzymes that are involved in threonine biosynthesis showed a significant difference in intracellular protein level between the mutant and native strain. The level of malate dehydrogenase was more than 30-fold higher in the mutant strain, whereas the synthesis of citrate synthase seemed to be severely inhibited in the mutant. Therefore, in the mutant, it is probable that the conversion of oxaloacetate into citrate was severely inhibited, but the oxidation of malate to oxaloacetate was significantly up-regulated. Accumulation of oxaloacetate may direct the metabolic flow towards the biosynthetic route of aspartate, a key metabolic precursor of threonine. Synthesis of aspartase (aspartate ammonia-lyase) was significantly inhibited in the mutant strain, which might lead to the enhanced synthesis of threonine by avoiding unfavourable degradation of aspartate to fumarate and ammonia. Synthesis of threonine dehydrogenase (catalysing the degradation of threonine finally back to pyruvate) was also significantly down-regulated in the mutant. The far lower level of cystathionine β-lyase synthesis in the mutant seems to result in the accumulation of homoserine, another key precursor of threonine. In the present study, we report that the accumulation of important threonine precursors, such as oxaloacetate, aspartate and homoserine, and the inhibition of the threonine degradation pathway played a critical role in increasing the threonine biosynthesis in the E. coli mutant.

Original languageEnglish
Pages (from-to)823-829
Number of pages7
JournalBiochemical Journal
Volume381
Issue number3
DOIs
Publication statusPublished - 2004 Aug 1

Keywords

  • Escherichia coli mutant
  • Proteomic response
  • Threonine biosynthesis
  • Two-dimensional gel electrophoresis (2-DE)

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Proteomic response analysis of a threonine-overproducing mutant of Escherichia coli'. Together they form a unique fingerprint.

  • Cite this