The role of cytochrome BD in supporting flagellar motility in E. Coli

The National Institute of Allergy and Infectious Diseases awarded Vanderbilt University $140,496 on January 21, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to investigate the role of cytochrome BD in supporting flagellar motility in uropathogenic Escherichia coli.

The research elucidates connections between bacterial aerobic respiration and flagellar motility in UPEC, the primary cause of urinary tract infections, with the goal of identifying pathways essential for UPEC pathogenesis to inform new therapeutic strategies. Preliminary findings establish that the quinol oxidase cytochrome BD is required for colonization and proliferation inside bladder cells and is essential for flagellar motility—a key fitness factor for UPEC. The study addresses a critical gap in knowledge by determining whether cytochrome BD sustains flagellar motility through overall respiratory flux support or through direct physical interaction with flagellar motor stator proteins. Two specific aims structure the research: determining how loss of cytochrome BD affects respiratory efficiency, and addressing the spatiotemporal relationship between cytochrome BD and the flagella.

Performance occurs at Vanderbilt University in Nashville, Tennessee. The period of performance runs from January 21, 2026, through August 31, 2028. This is a project grant, an assistance type supporting individual research investigators at nonprofit institutions.

Abstract

This proposal will elucidate connections between bacterial aerobic respiration and flagellar motility in uropathogenic escherichia coli (UPEC), the primary cause of urinary tract infections. A major focus of our lab is investigating the pathways that are essential for UPEC pathogenesis to aid in the development of new therapeutic strategies. Therapeutic strategies. Through our work, we have established that aerobic respiration is crucial for UPEC's survival in the hypoxic environment of the bladder, with the quinol oxidase cytochrome BD specifically required for colonization and proliferation inside bladder cells. Additionally, we observed that cytochrome BD is essential for flagellar motility, a key fitness factor in UPEC. The requirement of cytochrome BD for motility is surprising because UPEC encodes two other cytochrome oxidases that are functionally redundant. Therefore, this proposal aims to elucidate the mechanism of how cytochrome BD supports flagellar rotation in UPEC. My preliminary data suggests that cytochrome BD is required to support overall respiratory flux as mutants lacking cytochrome BD have impaired proton flux across the membrane. Additionally, a prevailing unknown in the field is whether enzymes are localized near the flagella to direcuy power flagellar rotation possibly through interacting with the stator proteins mowmotb. I hypothesize that cytochrome BD sustains flagellar motility either through support of overall respiratory flux or physical interaction with the flagellar motor. This hypothesis will be tested in two specific aims: aim 1 will determine how loss of cytochrome BD affects respiratory efficiency and aim 2 will address the spatiotemporal relationship between cytochrome BD and the flagella. This study will be the first to define a role for cytochrome BD in flagellar motility and address a critical GAP in knowledge of how flagellar rotation is energized. Given that cytochrome BD plays an essential role in infection, this information will be vital in the development of novel antimicrobials.