RELATIONSHIP BETWEEN METHIONINE UPTAKE AND DE-METHIOLATION IN A METHIONINE-UTILIZING MUTANT OF PSEUDOMONAS-FLUORESCENS UK1

Intact cells of P. fluorescens were used to determine whether demethiolation is a cytoplasmic reaction or a process by which the cell envelope eliminates excess methionine from the environment. Whenever methionine transport was inhibited, so was demethiolation, but inhibition of demethiolation did not necessarily lead to transport inhibition. The sensitivity of the demethiolation rate to reductions in the methionine transport rate indicated that the former is an intracellular reaction preceded by the entry of methionine via the permease. Since demethiolating activity was not increased over the control level with any of the supplemented amino acids, the rate of demethiolation was apparently not regulated by the permease activity.