MUTATIONS IN THE BORDETELLA-PERTUSSIS BVGS GENE THAT CONFER ALTERED EXPRESSION OF THE FHAB GENE IN ESCHERICHIA-COLI

The bvg locus of Bordetella pertussis, required for coordinate regulat ion of virulence genes in response to environmental signals, encodes t wo proteins, BvgS and BvgA, that belong to the bacterial two-component signal transduction systems. We have isolated spontaneous mutations o f the bvg locus in Escherichia coli and analyzed their effects on the expression fhaB::lacZY transcriptional fusions. The mutations, localiz ed in the linker and transmitter domain of BvgS, result in increased a ctivation of fhaB and/or in insensitivity to a modulating agent, nicot inic acid.