Simultaneous catabolite repression between glucose and toluene metabolism in Pseudomonas putida is channeled through different signaling pathways

Consejo Superior de Investigaciones Científicas, Estación Experimental del Zaidín, Dept. of Environmental Protection, C/Prof. Albareda, 1, E-18008 Granada, Spain

^* To whom correspondence should be addressed. Email: jlramos{at}eez.csic.es.

	Abstract

Pseudomonas putida KT2440 (pWW0) can use toluene via the TOL plasmid encoded catabolic pathways and glucose via a series of three peripheral chromosomal encoded routes that convert glucose into 6-phosphogluconate (6PG), namely, the glucokinase pathway in which glucose is transformed to 6PG through the action of glucokinase and glucose-6-phosphate dehydrogenase. Alternatively glucose can be oxidized to gluconate, which can be phosphorylated by gluconokinase to 6PG or oxidized to 2-ketogluconate, which, in turn, is further converted into 6PG. Our results show that KT2440 metabolizes glucose and toluene simultaneously, as revealed by net flux analysis of ¹³C-glucose. The determination of glucokinase and gluconokinase activities in glucose metabolism, gene expression assays using a fusion of the promoter of the Pu TOL upper pathway to 'lacZ, and global transcriptomic assays revealed simultaneous catabolite repression in the use of these two carbon sources. The effect of toluene on glucose metabolism was directed to the glucokinase branch and did not affect gluconate metabolism. Catabolite repression of the glucokinase pathway and the TOL pathway was triggered by two different catabolite repression systems. Expression from Pu was mainly repressed via PtsN in response to high levels of 2-dehydro-3-deoxygluconate-6-phosphate, whereas repression of the glucokinase pathway was channeled through Crc.