All cells need to communicate with their environment in order to survive. Bacteria employ two-component regulatory systems to accomplish this objective. The simplest systems consist of a sensor kinase, responsible for sensing an environmental change and a response regulator, whose output is altered in response to the signal (usually a change in gene expression). The system under study consists of EnvZ, the sensor and OmpR, the response regulator. OmpR regulates the genes encoding outer membrane proteins and their expression fluctuates in response to changes in the growth medium. The EnvZ/OmpR system is essential for many intracellular pathogens to replicate inside of host cells. The long-term goals are to understand how OmpR regulates gene expression, what the signal is that EnvZ senses and how this is transmitted across the membrane and eventually to OmpR. Recent work revealed two distinct signaling states of OmpR and proposed experiments will employ cysteine-substitutions and cross-linkers to examine the orientation of OmpR while bound to its target DNA. Previous measurements of EnvZ binding to OmpR have raised doubts regarding the ability of EnvZ to regulate OmpR-P levels in vivo and emphasize the need for a systematic examination of the biochemical properties and partial reactions of EnvZ. The goal is to delineate the steps important for signaling in molecular terms. Understanding how OmpR functions as a transcriptional activator and repressor, as well as the cues that it responds to will aid in understanding signal transduction in general as well as how OmpR regulates expression of virulence genes in pathogens.
Broader Impact-The goal is to contribute to the training of the nation's scientists and inspire young people to become interested in science. After visiting the lab, an eighth-grader wrote: "I really enjoyed learning from you about E. coli. I had no idea that studying E. coli could lead to curing different diseases." The lab participates in various science outreach programs that mentor high school students. This gives them an opportunity to participate in laboratory research and as a result, some of them choose science as a career. One of these students, now an undergraduate at Bowdoin College, is a co-author on her second scientific publication. Through the American Society of Microbiology, Mexican students were sponsored to work in the laboratory to learn new approaches, thus fostering international collaborations. Presently, a collaboration with colleagues in Mexico to establish a course sponsored by the ASM entitled "Application of Bacterial Genetics and Genomics to the Study of Infectious Disease" is underway for participants in Latin America. In addition to the impact gained by advancing scientific knowledge in our field, the research impacts on the training of young scientists.