Staphylococcus intermedius produces a functional agr autoinducing peptide containing a cyclic lactone

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• The accessory gene regulator (agr) system is a key regulator of virulence factors in staphylococci.
• This system relies on a two-component signal transduction pathway activated by an autoinducing peptide (AIP).
• AIPs typically feature a thiolactone bond involving a conserved cysteine, crucial for their function.

Purpose of the Study:

• To investigate the structure and function of the AIP in Staphylococcus intermedius.
• To determine if Staphylococcus intermedius deviates from the conserved cysteine-based AIP structure.
• To characterize the processing and activity of the Staphylococcus intermedius AIP.

Main Methods:

• Biochemical analysis of Staphylococcus intermedius AIP processing.
• Mass spectrometry to confirm AIP structure.
• Functional assays to assess autoinduction and cross-inhibition activities.

Main Results:

• The Staphylococcus intermedius AIP is processed by AgrB to form a cyclic lactone.
• This unique AIP contains a serine residue instead of the conserved cysteine.
• The serine-containing AIP functions as both an autoinducer and a cross-inhibitor.
• All tested Staphylococcus intermedius strains produce serine-containing AIPs.

Conclusions:

• Staphylococcus intermedius utilizes a distinct AIP structure, replacing conserved cysteine with serine.
• This serine-based AIP is functionally active, regulating virulence in Staphylococcus intermedius.
• The findings highlight the structural diversity within the conserved agr system across staphylococcal species.