Isocitrate lyase and malate synthase in Pseudomonas indigofera. II. Enzyme changes during the phase of adjustment and the early exponential phase.

Abstract

Howes, William V. (Washington State University, Pullman) and Bruce A. McFadden. Isocitrate lyase and malate synthase in Pseudomonas indigofera. II. Enzyme changes during the phase of adjustment and the early exponential phase. J. Bacteriol.84:1222-1227. 1962.-The differential rates of synthesis (DRS) of malate synthase and isocitrate lyase were investigated at 30 C during the phase of adjustment (lag) and the early exponential phase in Pseudomonas indigofera. Cells grown on ethanol-acetate-yeast extract or succinate-yeast extract were added to a medium containing ethanol or succinate, and the DRS of each enzyme was followed. A reproducible decline in both enzymatic activities occurred after inoculation when a lag in growth was observed. To define the DRS occurring after this decline, a new parameter, epsilon, was defined and calculated for linear segments of a DRS plot. Certain variations of epsilon during DRS suggested that a balance between induction (or derepression) and repression controls, in part at least, malate synthase and isocitrate lyase levels. Effects of chloramphenicol upon enzyme synthesis after the period of expected decline were studied. No degradation or synthesis of malate synthase occurred in the presence of chloramphenicol, although, after degradation, slight synthesis of isocitrate lyase occurred. Acetate, butyrate, ethanol, glyoxylate, and isocitrate did not stimulate production of either enzyme in nongrowing cultures of high cell density. In fact, some degradation of each enzyme occurred.