The PDZ Domain-Containing Protein Prc Is Involved in Virulence and Stress Tolerance in the Poplar Canker Bacterium <i>Lonsdalea populi</i>

Proteins harboring the PDZ domain are of utmost significance in the infection course of pathogenic bacteria, as well as in the response to external environmental stresses. In this study, we demonstrated that the <i>Lonsdalea populi</i> genome encodes a set of five proteins with the PDZ domain. Through a systematic inactivation of the genes responsible for encoding PDZ proteins, we showed that all these genes are closely related to the virulence of <i>L. populi</i>. Notably, deletion of <i>prc</i> results in suppression of the growth of <i>L. populi</i> and enhanced susceptibility to a diverse array of environmental stressors, such as hydrogen peroxide (H₂O₂), chloramphenicol, spectinomycin, and metal ions such as Mn²⁺, Fe²⁺, and Fe³⁺. Prc contains four domains: TSPn, PDZ, PEP, and DUF. By separately knocking out the four domains within Prc, we have demonstrated that the TSPn, PDZ, and PEP domains within Prc are all essential components in the pathogenic process of <i>L. populi</i>. Moreover, Prc interacts with the membrane protein YccA. This interaction regulates the biofilm formation capacity and motility of <i>L. populi</i>, thus exerting an impact on its virulence. Together, these findings suggest that Prc is an important regulator of virulence and stress response in <i>L. populi.</i>