The global transcription regulator XooClp governs Type IV pili system mediated bacterial virulence by directly binding to their promoters to coordinate virulence associated functions.

Type IV pili (TFP) play a crucial role in the sensing of the external environment by several bacteria. This surface sensing is essential for their lifestyle transitions and involvement in pathogenesis. However, the precise mechanisms underlying TFP's integration of environmental cues, particularly in regulating the TFP-Chp system and its effects on Xanthomonas physiology, social behavior, and virulence, remain poorly understood. In this study, we focused on investigating Clp, a global transcriptional regulator similar to CRP-like proteins, in Xanthomonas oryzae pv. oryzae, a plant pathogen. Our findings reveal that Clp integrates environmental cues sensed through DSF-quorum sensing into the TFP-Chp regulatory system. It accomplishes this by directly binding to TFP-Chp promoters in conjunction with intracellular levels of c-di-GMP, a ubiquitous bacterial second messenger, thereby controlling TFP expression. Moreover, Clp-mediated regulation is involved in regulating several cellular processes, including the production of virulence associated functions. Collectively, these processes contribute to host colonization and disease initiation. Our study elucidates the intricate regulatory network encompassing Clp, environmental cues, and the TFP-Chp system, providing insights into the molecular mechanisms that drive bacterial virulence in Xanthomonas spp. These findings offer valuable knowledge regarding Xanthomonas pathogenicity and present new avenues for innovative strategies aimed at combatting plant diseases caused by these bacteria.