Activation of the Cpx regulon destabilizes the F plasmid transfer activator, TraJ, via the HslVU protease in Escherichia coli.

摘要: The Escherichia coli CpxAR two-component signal transduction system senses and responds to extracytoplasmic stress. cpxA101* allele was previously found reduce F plasmid conjugation by post-transcriptional inactivation of the positive activator TraJ. Microarray analysis revealed upregulation protease-chaperone pair, HslVU, which shown degrade TraJ in an E. C600 background. Double mutants hslV or hslU restored wild-type levels. constitutive overexpression nlpE, outer membrane lipoprotein that induces Cpx stress response, also led HslVU-mediated degradation repression transfer. However, Cpx-mediated appears be growth phase-dependent, as induction nlpE mid-log phase cells did not appreciably alter Further, His6-TraJ sensitive HslVU vitro only when it purified from overexpressing nlpE. Thus, become resistant during normal growth, with this resistance mapping transfer region. Extracytoplasmic prevents modification TraJ, leaving susceptible HslVU. response indirectly controls synthesis mating apparatus, a complex transenvelope type IV secretion system, degrading