Host-derived fatty acids activate type VII secretion in Staphylococcus aureus.

Area of Science:

• Microbiology
• Molecular Biology
• Pathogenesis

Background:

• The type VII secretion system (T7SS) in Staphylococcus aureus is crucial for exporting virulence factors.
• T7SS contributes to bacterial survival and the persistence of abscess communities.
• T7SS expression is triggered by interactions with host tissues like blood serum and nasal secretions.

Purpose of the Study:

• To identify the host-derived factors that stimulate T7SS expression in Staphylococcus aureus.
• To elucidate the molecular mechanism linking host environmental sensing to T7SS activation.

Main Methods:

• Investigated the role of host fatty acids in T7SS regulation.
• Utilized genetic approaches to study the Staphylococcus aureus fatty acid kinase (FAK) complex and FakA.
• Analyzed the impact of incorporated fatty acids on bacterial membrane fluidity.

Main Results:

• Identified host-specific cis-unsaturated fatty acids as major stimulatory factors for T7SS.
• Demonstrated that Staphylococcus aureus fatty acid kinase (FAK) complex incorporates these fatty acids.
• Showed that FakA is essential for virulence and that incorporated fatty acids reduce bacterial membrane fluidity, contributing to T7SS activation.

Conclusions:

• Staphylococcus aureus senses the host environment through the incorporation of cis-unsaturated fatty acids.
• Altered membrane dynamics resulting from fatty acid incorporation are a key mechanism for T7SS activation.
• This pathway is vital for Staphylococcus aureus virulence and persistence in host infections.