Bfcr, a novel potential global regulator of marine Pseudomonas aeruginosa SM45 that enhances biofilm formation

Abstract

Biofilm formation is essential for the environmental adaptability of Pseudomonas aeruginosa. In this study, we identified a previously uncharacterized transcriptional regulator, Bfcr, that is closely associated with the enhanced biofilm formation of the marine strain P. aeruginosa SM45. Bfcr shares only 18.3% sequence identity with the known global regulator Vfr, but possesses the same domain architecture and shows high structural similarity, suggesting potential functional similarity. Bfcr contributes to biofilm formation through multiple mechanisms. Directly, it binds to and activates the psl operon, promoting biofilm matrix synthesis. Indirectly, Bfcr modulates several regulatory pathways linked to biofilm development, including the LasR system, cAMP/c-di-GMP signaling, and two-component system AauSR, thereby supporting stable biofilm production in SM45. Moreover, bfcr expression is regulated by Vfr, forming a hierarchical Vfr–Bfcr regulatory cascade. Phylogenetic analysis revealed that Bfcr was present in approximately 9% of the P. aeruginosa strains, which were dispersed across the branches of the evolutionary tree. Collectively, this study expands current understanding of the regulatory network governing P. aeruginosa biofilm formation. Bfcr provides new insight into how P. aeruginosa adapts to diverse environments and offers a potential target for strategies aimed at controlling biofilm-associated persistence.

Keywords

Pseudomonas aeruginosa / Biofilm / Bfcr / Global regulator

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The Author(s), under exclusive licence to Ocean University of China