The cell envelope of Gram-negative bacteria is a complex, dynamic compartment that is crucial for the survival of the cell. It provides a barrier between the cell and the surrounding milieu, ensures the structural integrity, and determines the morphology of the cell. The cell envelope is the site of many dynamic processes including solute, protein and nutrient transport, biosynthesis of many cellular macromolecules, and energy generation. In addition, the cell envelope can be remodeled in response to stresses such as changes in temperature and scarcity of nutrients, and is continually growing and changing as a result of cell cycle progression. The signal transduction pathways and corresponding responses that coordinate cell envelope processes and communicate information between the cytoplasm and cell envelope to maintain cellular homeostasis in bacteria are not fully understood. In Escherichia coli, one of the key pathways that senses the integrity of the cell envelope is controlled by the alternative sigma factor, s E , which has primarily been characterized for its role during cell envelope stress. s E is an essential gene, suggesting a role for s E beyond the stress response. The reason why this gene is required for viability is not known. The objectives of this project are to elucidate the role of s E in maintaining cell envelope integrity in unstressed cells and the regulatory pathways that coordinate s E activity with other regulatory events in the cell. This project also contains educational and public outreach components that focus on educating undergraduates and graduate students in the field, educating future science teachers, and informing the general public about current issues concerning microbiology.
