Molecular regulation of stress sensing and processing in gram-positive and gram-negative bacterial models.

PROJECT SUMMARY Bacteria use a remarkable array of responses to effectively survive and compete in ever-changing environmental and internal conditions. To do so, they must sense environmental or internal cues and then enact an appropriate response. Bacterial sensing impacts human health; for instance, stress-responding bacteria can be recalcitrant to antibiotic therapy, and some 100,000 Americans die each year from infections with antimicrobial-resistant bacteria. Bacterial responses can also impact other competing bacterial cells in the same niche, even killing them. We seek to learn more about these responses so that we can devise antimicrobial treatment strategies that either interfere with stress sensing or hijack bacterial response mechanisms to kill pathogens. Our research program uses two distinct bacteria—the classic model Bacillus subtilis and the notorious opportunistic human pathogen Pseudomonas aeruginosa—to tackle fundamental questions about the molecular components that undergird cue-sensing and control the corresponding responses. In B. subtilis, we have a special focus on the dynamics of environmental stress responses in single cells, asking how particular proteins impact response dynamics and how such dynamics influence cell growth and survival under stressful conditions. In P. aeruginosa, we mainly focus on the molecular regulation of pyocins, which are released by dying cells and can effectively kill other P. aeruginosa strains. In both projects, we have an eye toward leveraging stress sensing and pyocin production to improve antimicrobial therapy. We also study regulatory pathways and proteins that respond to important nutritional cues and influence virulence behaviors. In the questions we ask, we seek to understand the molecular interactions that connect internal or external cues to responses that confer competitive or fitness advantages. Using these tractable models, we bring together classical bacterial genetics, molecular techniques, fluorescence microscopy, and microfluidic technology. We anticipate these studies will yield a new and more mechanistic understanding of the principles that govern how bacterial cells sense internal and external cues, process those sensory inputs, and implement an effective response. The results, which flesh out the principles of the diverse systems under investigation, will have implications for understanding general features of systems that respond to stress or other responses across many biological systems as well as informing future strategies that counteract bacterial infectious disease and environmental contamination.