Thermal and Nutritional Regulation of Ribosome Hibernation in Staphylococcus aureus

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• The 100S ribosome, a dimeric form of the 70S complex, is found in bacteria but its regulation is poorly understood.
• Hibernating-promoting factor (HPF) mediates 100S ribosome formation in Staphylococcus aureus, influencing translational control and virulence.
• The regulatory pathways controlling HPF synthesis and 100S ribosome abundance in S. aureus remain largely unknown.

Purpose of the Study:

• To investigate the regulatory mechanisms controlling hpf gene expression and 100S ribosome abundance in Staphylococcus aureus.
• To elucidate the roles of the general stress response (GSR) sigma factor SigB and the transcription factor CodY in regulating hpf synthesis.
• To determine the impact of these regulatory pathways on S. aureus virulence and its response to environmental cues.

Main Methods:

• Utilized genetic analyses, including epistasis studies, to dissect the regulatory network.
• Investigated the integration of nutrient and thermal signals by CodY and SigB.
• Assessed the impact of hpf regulation on S. aureus virulence in a mouse model of septicemic infection.

Main Results:

• Identified SigB and CodY as key regulators of hpf expression in S. aureus.
• Demonstrated that CodY integrates nutrient and thermal signals to modulate hpf synthesis, acting as both an activator and repressor.
• Showed that CodY-mediated regulation of hpf influences S. aureus virulence, with CodY functioning upstream of SigB in a condition-dependent manner.
• Revealed that CodY-mediated activation of hpf masks a secondary hpf transcript from a SigB promoter.

Conclusions:

• CodY and SigB are critical regulators linking ribosome homeostasis, stress response, and virulence in S. aureus.
• The interplay between CodY, SigB, and hpf provides insights into bacterial adaptation and pathogenesis.
• This study uncovers potential new targets for therapeutic intervention against S. aureus infections by highlighting the connection between ribosome regulation and virulence.