Production of Aspartic Acid and Enzymatic Alteration in Pyruvate Kinase Mutants ofBrevibacterium flavum

Multiple Interaction of Fructose 1,6-Bisphosphate and Other Effectors on Phosphoenolpyruvate Carboxylase fromBrevibacterium flavumand Its Aspartate-producing Mutant

“…The enzyme activity was determined in the presence and absence (0) of FBP or acetyl-CoA. The assay mixture was the same as the standard assay mixture except for the indicated concentrations of PEP in (A), (C), and (E) or bicarbonate in (B), and for the addition of the following concentrations of FBP, 0.1 mM (e) in (A), 0.5mM Ce) in (B), 0.03 (e), 0.05 (6), and 0.1 mM (.) in (C), or acetyl-CoA, 0.007 (e), 0.01 (6), 0.02mM (.)…”

“…No. 2247 (ATCC 14067) and its aspartate-producing mutant No. 70 6 ) were used. These strains were aerobically cultured at 30°C for 20 hr in 500 ml-flasks containing 25 ml of medium 34 6 ) containing 300 tlg/liter of biotin.…”

“…1 ) Synthesis of the enzyme· is repressed by aspartate and glutamate,l) and the activity is feedback-inhibited by aspartate, and furthermore synergistically, by both aspartate and 2-oxoglutarate, a precursor of glutamate. 2 -S ) On the other hand, acetyl-CoA not only activates the enzyme 2 ,3) but also restrains its aspartate inhibition.2) Nevertheless, aspartate- 6 ) or lysine-7 ,S) overproduction by B. flavum mutants was found to be remarkably promoted by defects of pyruvate kinase or a reduction of pyruvate dehydrogenase activity, although these alterations seemed to decrease the intracellular level of acetyl-CoA. These findings suggest that another activator of the enzyme, fructose 1,6-bisphosphate (FBP), which has been reported with enteric bacteria, 9 -11 ) plays a physiologically important role in B.flavum.…”

Pyruvate Formation and Sugar Metabolism in an Amino Acid-Producing Bacterium,Brevibacterium flavum

“…70 3 ) was isolated as a revertant with a· normal level of homoserine dehydrogenase from strain 1-231 with a low level of the enzyme and lacking PK, which was derived from a B.flavum mutant, 15-8, and selected as to resistance to S-(2-aminoethyl)-L-cysteine and lysine-productivity. 12,13) The PK-Iacking mutant, No.…”

Influence of increased aspartate availability on lysine formation by a recombinant strain of Corynebacterium glutamicum and utilization of fumarate

“…No information exists to determine whether, in strains with feedback-insensitive aspartate kinase, a further limitation occurs in the steps converting aspartate to lysine or whether only a limiting aspartate supply is effective in these strains. As an indication for a limiting aspartate supply in lysine-producing cells, one mutant (15-8) of B. flavum was studied (11,13). This strain was isolated by random mutagenesis.…”