CPXP, A STRESS-COMBATIVE MEMBER OF THE CPX REGULON

The CpxA/R two-component signal transduction system of Escherichia col i can combat a variety of extracytoplasmic protein-mediated toxicities , The Cpx system performs this function, in part, by increasing the sy nthesis of the periplasmic protease, DegP, However, other factors are also employed by the Cpx system for this stress-combative function, In an effort to identify these remaining factors, we screened a collecti on of random lacZ operon fusions for those fusions whose transcription is regulated by CpxA/R, Through this approach, we have identified a n ew locus, cpxP, whose transcription is stimulated by activation of the Cpx pathway, cpxP specifies a periplasmic protein that can combat the lethal phenotype associated with the synthesis of a toxic envelope pr otein, In addition, we show that cpxP transcription is strongly induce d by alkaline pH in a CpxA-dependent manner and that cpxP and cpx muta nt strains display hypersensitivity to growth in alkaline conditions.