Catabolism of pipecolate to glutamate in Pseudomonas putida.

In the presence of pipecolate, Pseudomonas putida P2 (ATCC 25571) converts cu-amino[6-14C]adipate to radioactive glutamate with a 14C distribution of 11% and 80 % in carbons 1 and 5, respectively. This labeling pattern, when considered with previous data, indicates that a-aminoadipate is an obligate intermediate in the metabolism of pipecolate to glutamate. Some of the 14C in carbon 1 results from tricarboxylic acid cycle activity since cells incubated in the presence of malonate form glutamate with only 5.6% 14C in carbon 1. Cells incubated with DL-]W4C]pipecolate form [1J4C]glutamate, which distinguishes between two possible pathways for pipecolate catabolism. While this data excludes glutarate as an intermediate in the metabolism of pipecolate to glutamate, DL-cw-amino[6-*4C]adipate forms radioactive ghtarate and [l ,5-14C]glutarate forms [l ,5-14C]glutamate. From these results and earlier studies it is concluded that the major pathway for L-pipecolate catabolism in P. putida P2 is different from that in mammals. A proposed pathway includes enzyme-bound, or derivatives of, glutarate, glutaconate, and a-hydroxyglutarate as intermediates. The pathway for formation of radioactive glutarate from DL-(uamino[6-14C]adipate is unknown but could represent a minor contribution by a second catabolic pathway. Radioactive glutamate formed from [l ,V4C]glutarate containing 14C in carbon 1 is evidence for a glutarate catabolic route different from that inferred for Pseudomonas jfuorescens and mammalian tissue.