Enterococcal Rgg-like regulator ElrR activates expression of the elrA operon

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Enterococcus faecalis virulence is linked to ElrA, a leucine-rich protein.
• ElrA enhances bacterial persistence in macrophages and IL-6 cytokine production.
• ElrA expression is typically low in vitro but induced during infection.

Purpose of the Study:

• Identify regulatory elements controlling elrA expression.
• Investigate the role of novel regulatory proteins in E. faecalis virulence.
• Characterize the function of the Rgg family regulator, ElrR.

Main Methods:

• Quantitative reverse transcription-PCR (qRT-PCR) to measure gene expression.
• Translational lacZ fusions to assess protein activity and regulation.
• Electrophoretic mobility shift assays (EMSAs) to study protein-DNA interactions.
• Murine peritonitis model to evaluate bacterial virulence.

Main Results:

• Identified ef2687 (renamed elrR) as a positive regulator of elrA.
• Demonstrated ElrR positively regulates elrA expression.
• Observed attenuated virulence in a ΔelrR mutant strain in a mouse model.
• Evidence suggests ElrR-independent elrA expression and additional ElrR-controlled virulence genes in vivo.

Conclusions:

• ElrR is a key positive regulator of the E. faecalis virulence gene elrA.
• ElrR plays a significant role in E. faecalis pathogenesis.
• Further investigation is needed to understand ElrR-independent elrA regulation and other ElrR targets.