|
type |
Journal Article |
authors |
Sahm, H.; Eggeling, L.; Eikmanns, B.; Kramer, R. |
title |
Construction of L-lysine-, L-threonine-, and L-isoleucine-overproducing strains of Corynebacterium glutamicum |
journal |
Ann N Y Acad Sci |
Activity |
4.3.1.19 |
Family |
4.3.1.19 |
ui |
96250132 |
year |
(1996) |
volume |
782 |
pages |
25-39. |
| |
keywords |
Biotechnology/methods |
abstract |
The gram-negative bacterium Corynebacterium glutamicum is used for the industrial production of amino acids, for example, of L-glutamate and L- lysine. By cloning and expressing the various genes of the L-lysine pathway in C. glutamicum, we would demonstrate that an increase of the flux of L-aspartate semialdehyde to L-lysine could be obtained in strains with increased dihydrodipicolinate synthase activity. Recently we detected that in C. glutamicum two pathways exist for synthesis of D,L-diaminopimelate and L-lysine. Mutants defective in one pathway are still able to synthesize enough L-lysine for growth, but the L-lysine secretion is reduced to 50 to 70%. Using NMR spectroscopy, we could calculate how much of the L-lysine secreted into the medium is synthesized via either one or the other pathway. Amplification of the feedback inhibition insensitive homoserine dehydrogenase and homoserine kinase in a high L-lysine-overproducing strain enabled channeling of the carbon flow from the intermediate aspartate semialdehyde towards homoserine, resulting in a high accumulation of L-threonine. For a further flux from L-threonine to L-isoleucine, the allosteric control of threonine dehydratase was eliminated. |
last changed |
2008/04/01 16:02 |
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