Elucidating Molecular Mechanism and Signaling Pathway of Novel Protease System RhpPC in Regulating Pathogenicity of Pseudomonas Syringae

Project: Research

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Pseudomonas syringae, the leading cause of crop diseases world-wide, uses type III secretion system (T3SS) to invade host plants. T3SS of plant pathogenic bacteria is induced in the plant and minimal media (MM). Although a number of components regulating the T3SS gene expression have been identified, how bacteria sense the environmental conditions and further transduce the signal(s) to the known regulatory components remain largely unknown. We have recently found a novel protease system RhpPC as a major regulator of T3SS in P. syringae. In our previous studies, we found that RhpPC was localized to the cytoplasm and regulated the in vivo protein level of HrpL, a key regulator of the T3SS genes. We also have done a transposon-insertion mutant screening, and identified osmolarity-sensing two-component system histidine kinase EnvZ as a regulator of rhpPC. We propose a novel signaling pathway of osmolarity-EnvZ-OmpR-RhpPC-HrpL-T3SS, whose verification is the focus of the proposal. Genetic and biochemical characterizations of RhpPC-pathway is the first step toward identifying signals to which the T3SS responds, and toward the development of new strategies for disease control based on T3SS manipulation. Our long-term goal is to leverage the outcomes of the herein proposed studies to develop better therapies against P. syringae infection. 


Project number9042789
Grant typeGRF
Effective start/end date1/01/20 → …