Interactions of a conserved regulatory switch controls physiology in bacilli and clostridia

The National Institute of Allergy and Infectious Diseases awarded Emory University $100,228 on September 30, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to investigate the regulatory mechanisms controlling sporulation, motility, and virulence in spore-forming bacteria.

The project focuses on the role of SPO0E, a conserved regulatory protein that controls the transition from vegetative bacterial cells to dormant spores in Bacilli and Clostridia species. The research will identify critical SPO0E amino acid regions and define its interactions with SPO0A and other partner regulators, addressing gaps in understanding how pathogenic spore-forming bacteria initiate sporulation—a mechanism underlying over one million infections annually. The work is organized around two specific aims involving mutagenesis studies and characterization of protein interactions relevant to sporulation, motility, and toxin production across multiple bacterial species.

Performance runs through September 29, 2028, at Emory University in Atlanta, Georgia. Emory University Office of Sponsored Programs Division is the recipient; the project grant is classified as assistance funding.

Abstract

Pathogenic spore-forming bacteria cause over one million infections, costing billions of dollars in healthcare costs, and thousands of deaths annually. Sporulating bacteria rely on the transition from a vegetative state to spore for survival. A dormant bacterial spore can survive unfavorable conditions for millions of years. This is because spores are extremely resistant to heat, chemicals, and radiation. To prevent spore-related diseases, IT is crucial to uncover how these bacteria decide to initiate sporulation. Yet, there is a GAP in knowledge of the mechanisms behind bacterial sporulation initiation and transmission. Sporulation initiation is activated by the master transcriptional regulator, SPO0A. Previous data show that SPO0A phosphorylation activates sporulation. However, SPO0A activation can be blocked, preventing spore formation. SPO0E is a key regulator in all spore formers that can inhibit sporulation by inactivating SPO0A. In addition, SPO0E was recently found to control motility, as well as virulence in some species. However, the specific interactions that allow SPO0E to regulate sporulation, motility, and toxin production in different bacteria remain unclear. The long-term goal of this project is to identify how SPO0E controls the switch from a motile vegetative cell state to a dormant spore. Based on prior data, my central hypothesis is that SPO0E evolved to regulate physiology through specific interactions with the major effectors of virulence, motility, and sporulation in bacilli and clostridia. The specific objectives are to determine the SPO0E regions critical for its physiologic functions and to define SPO0E interactions with SPO0A and other partner regulators. The hypothesis will be tested through experiments detailed in two specific aims. In specific aim 1, SPO0E amino acid residues of interest will be mutated to investigate their impact on sporulation and motility/toxin production in clostridioides difficile and bacillus subtilis. In specific aim 2, SPO0E variants from both species will be tested for their ability to interact with binding partners using molecular biology and biochemical approaches. These experiments will uncover how SPO0E homologs regulate major physiological processes in spore-forming firmicutes. This research is conceptually innovative because IT explores the overlap and divergences in sporulation initiation between B. Subtilis and C. Difficile. The proposed research is also significant because IT ultimately gives insight to the evolution of critical B. Subtilis and C. Difficile regulatory mechanisms. Overall, this research will provide a foundation in understanding targets of sporulation and motility in sporulating bacteria and an excellent training for my doctoral studies to support my career goals.