The Staphylococcus aureus non-coding RNA IsrR regulates TCA cycle activity and virulence

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• Staphylococcus aureus adapts to low iron conditions in hosts.
• The ferric uptake transcriptional regulator (Fur) controls iron homeostasis.
• Iron availability impacts bacterial growth and virulence.

Purpose of the Study:

• Investigate the role of Fur and regulatory RNA in Staphylococcus aureus iron metabolism.
• Identify mechanisms of iron acquisition and their impact on virulence.
• Characterize the interaction between IsrR and its target transcripts.

Main Methods:

• Utilized a suppressor screen to identify mutations affecting bacterial growth.
• Performed gene expression analysis (acnA, sdhC, mqo, citZ, citM).
• Conducted in vitro binding assays and in vivo infection models (murine skin, pneumonia).

Main Results:

• A Δfur mutant showed reduced acnA expression and impaired growth.
• Decreased IsrR transcription restored acnA expression and growth.
• IsrR directly binds acnA and other metabolic transcripts, promoting iron uptake.
• Both Fur and IsrR contribute to Staphylococcus aureus infection.

Conclusions:

• IsrR plays a significant role in Staphylococcus aureus iron acquisition and virulence.
• IsrR acts independently of Fur to modulate iron-dependent gene expression.
• Targeting IsrR could be a strategy to combat Staphylococcus aureus infections.