Essential role of aspartokinase in L-threonine production by Escherichia coli W mutants.
Open Access
- 1 January 1986
- journal article
- Published by Oxford University Press (OUP) in Agricultural and Biological Chemistry
- Vol. 50 (4) , 1015-1018
- https://doi.org/10.1271/bbb1961.50.1015
Abstract
We previously constructed an L-threonine-producing strain of E. coli W, KY8280, which is an Ile+ revertant of KY8279 which requires L-methionine, α, ε-diaminopimelic acid and L-isoleucine [H. Kase et al., Agric. EM. Chem., 35, 2089 (1971)]. From KY8280, another L-threoninehyperproducing strain, KY8366, was obtained as an α-amino-β-hydroxyvaleric acid (AHV, a threonine analog)-resistant mutant. Enzymatic analysis revealed that KY8280 constitutively expressed 8-fold higher L-threonine-sensitive aspartokinase I activity than KY8279. In addition, KY8366 constitutively expressed 13-fold higher L-lysine-sensitive aspartokinase III activity than KY8280. Such elevated levels of aspartokinases may contribute to the hyperproduction of L-threonine by these mutant strains. KY8366 produced 28 mg/ml of L-threonine in a culture medium fed with 12% glucose.Keywords
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