Disruption of Malate : Quinone Oxidoreductase Increases L-Lysine Production by Corynebacterium glutamicum
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Genomic analysis of a classically derived <small>L</small>-lysine-producing mutant, <I>Corynebacterium glutamicum</I> B-6, identified a nonsense mutation in the <I>mqo</I> gene, which encodes malate:quinone oxidoreductase (MQO). The effect of <I>mqo</I> disruption on <small>L</small>-lysine production was investigated in a defined <small>L</small>-lysine producer, <I>C. glutamicum</I> AHP-3, showing approximately 18% increased production. To explore the underlying mechanisms of the increase, the <I>mqo</I>-disrupted strain was analyzed from the viewpoints of redox balance, activities of membrane-bound dehydrogenases, and transcriptome. The intracellular [NADH]/[NAD] ratio in the strain remained unchanged. Also, there were no significant differences in the activities of the membrane-bound dehydrogenases examined. However, transcriptome analysis showed that some TCA cycle genes, such as <I>acn</I>, <I>sucC</I>, and <I>sucD</I>, were down-regulated in the strain. These results suggest that the loss of MQO activity down-regulates the flux of the TCA cycle to maintain the redox balance and results in redirection of oxaloacetate into <small>L</small>-lysine biosynthesis.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(11), 2803-2806, 2006-11-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry