The University of Chicago
Multiscale investigation of photo sensing in non-photosynthetic bacteria
Bacterial responses to self-generated and environmental stimuli influence their survival, persistence in particular niches, and lifestyle transitions between individual behaviors such as swimming and collective behaviors such as formation of antibiotic-resistant communities called biofilms. Biofilm development is governed by various physical, chemical and biological stimuli. How the information encoded in multiple sensory inputs is extracted and integrated to control collective behaviors is largely mysterious. The overarching goal of my research program is to develop a comprehensive understanding of the molecular mechanisms that allow bacteria to sense and respond to light (physical cue), nutrient availability (chemical cue) and presence of other bacteria i.e., quorum (biological cue), individually and in combination. To this end, we focus on the three research areas outlined below. Together, these studies will be foundational for designing successful synthetic strategies to enhance or to inhibit biofilms and for developing novel therapeutic interventions.
1. Photo sensory signal transduction. Light is detected by photoreceptors in all domains of life. Surprisingly, the function of photosystems in non-photosynthetic bacteria are mostly unknown. I have identified an entire photo-sensing cascade in the human pathogen Pseudomonas aeruginosa — enabling crucial insight into light-driven control of bacterial behaviors relevant to human disease. We will characterize the photo-sensing signaling system, define the physiological role of light and explore the possibility of using light as an antibacterial therapeutic.
2. Convergence of sensory signaling pathways. It is imperative that bacteria integrate varied sensory cues to make key behavioral transitions; however, the mechanisms by which they do so are poorly understood. We will identify the molecular mechanisms by which information from photo sensing, nutrient sensing and quorum sensing are combined into the control of biofilm formation, and we will investigate how photo sensing intersects with other sensory pathways to control bacterial behaviors.
3. Sensory regulation of biofilm dispersal. Biofilm dispersal, the final portion of the biofilm lifecycle, involves the coordinated release of differentiated motile cells. To disperse, bacteria must terminate group behaviors and transition into executing individual behaviors such as producing flagella and regaining motility. The sensory mechanisms controlling biofilm dispersal are not well understood. We will determine the roles of photo sensing, nutrient sensing and quorum sensing in the process of dispersal and determine how flagellar motility is triggered to make the transition from the sessile to the motile state.