title: The effect of intracellular ppGpp levels on glutamate and lysine overproduction in Escherichia coli.
abstract: Although the enhancement of amino-acid synthesis by guanosine-3',5'-tetraphosphate (ppGpp) is well known, the effect of intracellular ppGpp levels on amino-acid overproduction in Escherichia coli has not been investigated. In this study, we demonstrate that overexpression of the relA gene, encoding ppGpp synthetase, increases the accumulation of amino acids, such as glutamate and lysine, in amino-acid-overproducing strains of E. coli. Elevation of intracellular ppGpp levels due to depletion of required amino acids also enhances glutamate overproduction. Moreover, the extent of overproduction is highly dependent on the intracellular ppGpp level. These results demonstrate that amino-acid overproduction in E. coli is closely connected to amino-acid auxotrophy via the accumulation of ppGpp.
authors.affiliation: Laboratories of Fermentation and Biotechnology, Ajinomoto, CO., Inc., Kawasaki-shi, Kanagawa 210-8681, Japan. akira_imaizumi@ajinomoto.com <akira_imaizumi@ajinomoto.com>
authors.forename: Akira
authors.initials: A
authors.lastname: Imaizumi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kojima
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Matsui
mesh_terms: D000596:Amino Acids / Q000096:biosynthesis; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D018698:Glutamic Acid / Q000096:biosynthesis*; D006159:Guanosine Tetraphosphate / Q000378:metabolism / Q000494:pharmacology*; D042541:Intracellular Space / Q000378:metabolism; D008239:Lysine / Q000096:biosynthesis*; D051996:Transcription Factor RelA / Q000235:genetics; D014169:Transformation, Bacterial
chemical_list: D000596:Amino Acids; D051996:Transcription Factor RelA; D006159:Guanosine Tetraphosphate; D018698:Glutamic Acid; D008239:Lysine