AUTHOR=Chakraborty Smarajit , Kenney Linda J. 

TITLE=A New Role of OmpR in Acid and Osmotic Stress in Salmonella and E. coli

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02656

DOI=10.3389/fmicb.2018.02656

ISSN=1664-302X

ABSTRACT=<p>Bacteria survive and respond to diverse environmental conditions and during infection inside the host by systematic regulation of stress response genes. <italic>E. coli</italic> and <italic>S</italic>. Typhimurium can undergo large changes in intracellular osmolality (up to 1.8 Osmol/kg) and can tolerate cytoplasmic acidification to at least pH<sub>i</sub> 5.6. Recent analyses of single cells challenged a long held view that bacteria respond to extracellular acid stress by rapid acidification followed by a rapid recovery. It is now appreciated that both <italic>S</italic>. Typhimurium and <italic>E. coli</italic> maintain an acidic cytoplasm through the actions of the outer membrane protein regulator OmpR via its regulation of distinct signaling pathways. However, a comprehensive comparison of OmpR regulons between <italic>S</italic>. Typhimurium and <italic>E. coli</italic> is lacking. In this study, we examined the expression profiles of wild-type and <italic>ompR</italic> null strains of the intracellular pathogen <italic>S</italic>. Typhimurium and a commensal <italic>E. coli</italic> in response to acid and osmotic stress. Herein, we classify distinct OmpR regulons and also identify shared OmpR regulatory pathways between <italic>S</italic>. Typhimurium and <italic>E. coli</italic> in response to acid and osmotic stress. Our study establishes OmpR as a key regulator of bacterial virulence, growth and metabolism, in addition to its role in regulating outer membrane proteins.</p>