Weak Organic Acids Decrease Borrelia burgdorferi Cytoplasmic pH, Eliciting an Acid Stress Response and Impacting...

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Borrelia burgdorferi, the causative agent of Lyme disease, exists in diverse environments, including tick vectors and host organisms.
• The bacterium dynamically regulates gene expression in response to environmental cues to ensure survival and adaptation.

Purpose of the Study:

• To investigate the impact of weak monocarboxylic organic acids on Borrelia burgdorferi's cytoplasmic pH and gene expression.
• To identify genes and regulatory pathways involved in the acid stress response of Borrelia burgdorferi.

Main Methods:

• Exposure of Borrelia burgdorferi cultures to weak monocarboxylic organic acids in vitro.
• Measurement of cytoplasmic pH changes.
• Analysis of gene expression patterns, focusing on RpoN, RpoS, and BosR-dependent genes.

Main Results:

• Exposure to organic acids decreased the cytoplasmic pH of Borrelia burgdorferi.
• Acid stress induced the expression of genes encoding pH homeostasis mechanisms, including proton/cation exchangers and a Na+/H+ antiporter.
• The acid stress response activated RpoN- and RpoS-dependent genes, including key virulence factors such as outer surface protein C (OspC) and BBA66.

Conclusions:

• Cytoplasmic acidification is a significant environmental cue for Borrelia burgdorferi.
• The acid stress response involves complex regulatory networks, including RpoN, RpoS, and BosR, impacting virulence factor expression.
• The interconnectedness of virulence factor regulation with general stress responses highlights the multifactorial nature of bacterial adaptation and transmission.