Cracking the Microbial Language: Characterization of Novel Biocatalysts for Interfering with Signaling to Illuminate Quorum Sensing Mechanisms

PROJECT SUMMARY / ABSTRACT Bacteria are important to human health and therefore, effective control strategies are critical to mitigate the risks posed by microbial activities. The current paradigm of chemical (antibiotics) control is eroding with the escalating challenge from resistance, and new strategies are needed. Quorum sensing (QS), a communication system utilized by bacteria and based on signaling molecules is appealing because it controls several bacterial behaviors. However, our current understanding of QS and our ability to manipulate is rudimentary. Here we propose to comprehensively investigate QS using interference strategies, specifically enzymes such as lactonases that can degrade the signaling molecules N-acyl-homoserine lactones, to decode the microbial language. Our group demonstrated the efficacy of interference in QS using these enzymes across various contexts, including monocultures and complex communities. Yet, challenges remain in achieving the selectivity needed to specifically isolate the contribution of individual signals and infer their biological roles. We propose to address critical gaps in QS interference by elucidating its effects on bacterial behavior and interspecies competition. Additionally, we will continue to unravel the molecular determinants governing lactonase mechanisms and substrate selectivity. Lastly, we will characterize and enhance enzymes capable of degrading orthogonal signals, such as autoinducing peptides (AIPs) to considerably expanding the scope of QS manipulation. The expected impact from this proposal extends beyond the fundamental insights into bacterial communication. By unveiling novel regulatory mechanisms and advancing our enzymatic understanding, this work will enable the design of highly specific quorum quenchers. Ultimately, these findings will inform bacterial control strategies with implications for human health and beyond.