InterPro domain: IPR003710

ApbA, the ketopantoate reductase enzyme 1.1.1.169 of Salmonella typhimurium is required for the synthesis of thiamine via the alternative pyrimidine biosynthetic pathway [ 1 ]. Precursors to the pyrimidine moiety of thiamine are synthesized de novo by the purine biosynthetic pathway or the alternative pyrimidine biosynthetic (APB) pathway. The ApbA protein catalyzes the NADPH-specific reduction of ketopantoic acid to pantoic acid. This activity had previously been associated with the pantothenate biosynthetic gene panE [ 2 ]. ApbA and PanE are allelic [ 3 ].

This entry also include budding yeast Pan5, which is a 2-dehydropantoate 2-reductase involved in the (R)-pantothenate biosynthesis [ 3 ].

1. ApbA, the ketopantoate reductase enzyme of Salmonella typhimurium is required for the synthesis of thiamine via the alternative pyrimidine biosynthetic pathway. J. Biol. Chem. 273, 5572-6
2. The panE gene, encoding ketopantoate reductase, maps at 10 minutes and is allelic to apbA in Salmonella typhimurium. J. Bacteriol. 180, 4757-9
3. Saccharomyces cerevisiae is capable of de Novo pantothenic acid biosynthesis involving a novel pathway of beta-alanine production from spermine. J. Biol. Chem. 276, 10794-800