Synthesis and Secretion of Erwinia chrysanthemi Virulence Factors Are Coregulated . Guy Condemine . Laboratoire de Genetique Moleculaire des Microorganismes, CNRS URA 1486, INSA Bat 406, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex, France. Janine Robert-Baudouy Laboratoire de Genetique Moleculaire des Microorganismes, CNRS URA 1486, INSA Bat 406, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex, France. MPMI 8:632-636. Accepted 6 April 1995. Copyright 1995 The American Phytopathological Society.

Regulation of the transcription of four operons (outS, outB, outT, outC-M) coding for components of the protein secretion apparatus of Erwinia chrysanthemi has been studied. Regulation of the outC operon expression by kdgR, which is the repressor of all the genes involved in peclinolysis, requires the outT gene product, suggesting that OutT could be a transcriptional activator of outC. The gene pecS, which regulates pel and celZ gene expression, also negatively controls the outC operon in a manner independent of the regulation by OutT. All environmental conditions that affect pectale lyase production also modulate Out protein synthesis. Thus, pectate lyase synthesis and secretion are very tightly coregulated.