Significance of the non-oxidative route of the pentose phosphate pathway for supplying carbon to the purine-nucleotide pathway in Corynebacterium ammoniagenes.

To evaluate the strategy of supplying ribose 5-phosphate to the purine-nucleotide pathway exclusively via the nonoxidative route, the glucose 6-phosphate dehydrogenase gene zwf was disrupted in inosine- and 5'-xanthylic acid-producers of Corynebacterium ammoniagenes. In both producers, interruption of the oxidative route caused a decrease in production yields of about 50%. Attempts to increase the capacity of the nonoxidative route through overexpression of the transketolase or transaldolase gene in the zwf mutants led to no discernable effects on production, indicating that, in C. ammoniagenes, the nonoxidative route alone cannot provide sufficient ribose 5-phosphate for high-level production, although nonoxidative synthesis of the precursor is possible.