Elevated zinc induces siderophore biosynthesis genes and a zntA-like gene in Pseudomonas fluorescens

Zinc-regulated genes were analyzed in Pseudomonas fluorescens employing mut agenesis with a reporter gene transposon. Six mutants responded with increa sed gene expression to elevated concentrations of zinc. Genetic and biochem ical analysis revealed that in four of the six mutants the transposon had i nserted into genes essential for the biosynthesis of the siderophore pyover dine. The growth of one of the mutants was severely impaired in the presenc e of elevated concentrations of cadmium and zinc ions. In this mutant, the transposon had inserted in a gene with high similarity to P-type ATPases in volved in zinc and cadmium ion transport. Four mutants reacted with reduced gene expression to elevated concentrations of zinc. One of these mutants w as sensitive to zinc, cadmium and copper ions. The genetic region targeted in this mutant did not show similarity to any known gene. (C) 2000 Federati on of European Microbiological Societies. Published by Elsevier Science B.V . All rights reserved.