Sequential appearance of radiolabel-tagged cyclohexadienyl derivatives of shikimate in Neurospora

Abstract

The growing interest in the arogenate molecule and its derivatives in applied plant biochemistry stems from its regulation of the first enzyme in the aromatic pathway. The recent finding of a new derivative of arogenate (spiro-arogenate) in a mutant of Neurospora crassa raised the question of the biosynthetic sequence of cyclohexadienyl shikimate derived metabolites. Specifically labeled tritiated shikimate was used as a tracer. We have observed the uptake and metabolism of shikimate by this mutant. We have also demonstrated conclusively in vivo that arogenate appears prior to spiro-arogenate in this strain. The levels of accumulation of the various nonaromatic shikimate metabolites were determined in the cells. Intracellular arogenate levels exceeded prephenate levels which is exactly the opposite of results obtained in the culture supernate.