This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vrljic, M. Articles by Eggeling, L. Search for Related Content PubMed PubMed Citation Articles by Vrljic, M. Articles by Eggeling, L.

 Previous Article  |  Next Article 

J. Bacteriol., 07 1995, 4021-4027, Vol 177, No. 14
Copyright © 1995, American Society for Microbiology

Unbalance of L-lysine flux in Corynebacterium glutamicum and its use for the isolation of excretion-defective mutants

M Vrljic, W Kronemeyer, H Sahm and L Eggeling
Biotechnologie 1, Forschungszentrum Julich GmbH, Germany.

We found that the simple addition of L-methionine to the wild type of Corynebacterium glutamicum results in excretion of the cellular building block L-lysine up to rates of 2.5 nmol/min/mg (dry weight). Biochemical analyses revealed that L-methionine represses the homoserine dehydrogenase activity and reduces the intracellular L- threonine level from 7 to less than 2 mM. Since L-lysine synthesis is regulated mainly by L-threonine (plus L-lysine) availability, the result is enhanced flux towards L-lysine. This indicates a delicate and not well controlled type of flux control at the branch point of aspartate semialdehyde conversion to either L-lysine or L-threonine, probably due to the absence of isoenzymes in C. glutamicum. The inducible system of L-lysine excretion discovered was used to isolate mutants defective in the excretion of this amino acid. One such mutant characterized in detail accumulated 174 mM L-lysine in its cytosol without extracellular excretion of L-lysine, whereas the wild type accumulated 53 mM L-lysine in the cytosol and 5.9 mM L-lysine in the medium. The mutant was unaffected in L-lysine uptake or L-isoleucine or L-glutamate excretion, and also the membrane potential was unaltered. This mutant therefore represents a strain with a defect in an excretion system for the primary metabolite L-lysine.

This article has been cited by other articles:

• Cahyanto, M. N., Kawasaki, H., Nagashio, M., Fujiyama, K., Seki, T. (2006). Regulation of aspartokinase, aspartate semialdehyde dehydrogenase, dihydrodipicolinate synthase and dihydrodipicolinate reductase in Lactobacillus plantarum. Microbiology 152: 105-112 [Abstract] [Full Text]  
• Bellmann, A., Vrljic, M., Patek, M., Sahm, H., Kramer, R., Eggeling, L. (2001). Expression control and specificity of the basic amino acid exporter LysE of Corynebacterium glutamicum. Microbiology 147: 1765-1774 [Abstract] [Full Text]