Title: "Antimicrobial peptide stress response in E. coli"

Speaker: Dr. Srujana Samhita Yadavalli

Abstract: One of the major public health concerns today is the dramatic rise of antimicrobial resistance. To counter this challenge, we must first understand the biochemical and regulatory pathways that underlie this resistance. My research is focused on signaling systems underlying stress response in bacteria. I discovered that treating E. coli with sublethal concentrations of antimicrobial peptides (AMPs) causes cells to filament and this response is dependent on the PhoQ/PhoP signaling system. The PhoQ/PhoP two-component system is an important pathway for survival in response to signals such as cationic antimicrobial peptides (AMPs), low Mg²⁺ and acidic pH, and regulates virulence in E. coli, Salmonella, Yersinia and related bacteria. My work demonstrated that this block in cell division is the result of high stimulus through this two-component system and is mediated by a tRNA modification enzyme (QueE), which directly binds and inhibits the division complex in E. coli. The control of septation by PhoQ/PhoP may protect cells from antimicrobial peptide-induced stress via stimulation of this signaling system. My research program aims to study stress response pathways in pathogenic bacteria. Specifically, I will investigate the unexpected roles of posttranscriptional tRNA modification machinery in modulating key cellular processes such as cell division and global stress response. My lab will also study the role of small proteins encoded by tiny open reading frames <200 bp, in bacterial gene regulation. My research program integrates tools from genetic engineering, microbiology and biochemistry to address fundamental questions in bacterial stress response.