High-throughput suppressor screen demonstrates that RcsF monitors outer membrane integrity and not Bam complex function
Muralidhar Tata, Santosh Kumar, Sarah R. Lach, Shreya Saha, Elizabeth M. Hart, Anna Konovalova
Abstract
Significance The bacterial cell envelope is the frontline defense against host immune factors and antibiotics. The regulator of capsule synthesis (Rcs) is a complex signaling pathway that maintains the homeostasis of this essential organelle. Several hypotheses for how the sensory component RcsF activates signaling in response to stress were proposed but could not be directly tested because RcsF proper assembly into the complex with outer membrane proteins (OMPs) depends on the essential β-barrel assembly machine (Bam). We used an extensive genetic analysis to tease apart which RcsF interactions are important for the sensing function. We show that RcsF does not monitor the Bam complex function. Instead, the Bam complex is required to assemble the sensory RcsF/OMP complex that monitors membrane integrity.