Analysis of Putative CzcR Targets Under Zinc Sufficiency and Zinc Excess Conditions in Pseudomonas aeruginosa Using ChIP-Seq

Pseudomonas aeruginosa is a versatile opportunistic pathogen that thrives in hostile environments by tightly regulating zinc (Zn) homeostasis. The CzcRS two-component system is pivotal for Zn resistance, primarily by activating the CzcCBA efflux pump, yet its basal activity and full regulon remain poorly defined. Here, we analyzed putative CzcR targets under zinc sufficiency (ZS) and zinc excess (ZE) conditions in P. aeruginosa PAO1 using ChIP-seq. Under ZE, we identified 32 CzcR binding sites, potentially regulating 39 genes, many of which are linked to virulence, antibiotic resistance, and stress response. Under ZS, 10 binding sites were detected, revealing distinct CzcR targets. Considering the presence of a CzcR binding motif close to the peaks summit and RNA-seq data, we identified seven and four novel CzcR-regulated genes under ZE and ZS conditions, respectively, mostly implicated in bacterial virulence. Our findings highlight that CzcR may exhibit different functionalities depending on Zn concentration: its basal activity maintains physiological robustness, while its activated form orchestrates Zn detoxification and virulence modulation. This study expands our understanding of how P. aeruginosa integrates metal sensing with clinically relevant phenotypes, highlighting CzcR as a key regulator at the intersection of metal homeostasis and pathogenicity.