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Characterization of MroQ-Dependent Maturation and Export of the Staphylococcus aureus Accessory Gene Regulatory

Madison R Stock1, Liwei Fang2, Kaelie R Johnson2

  • 1Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA.

Infection and Immunity
|September 8, 2022
PubMed

Insights

MroQ is crucial for the maturation and activity of most Staphylococcus aureus autoinducing peptides (AIPs), except for Agr-III type, impacting bacterial virulence.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Gram-positive bacteria utilize autoinducing peptides (AIPs) for regulating adaptive traits, including virulence.
  • Staphylococcus aureus employs the accessory gene regulatory (Agr) system to control virulence factors via cyclic AIPs.
  • S. aureus strains are classified into four Agr groups (Agr-I to -IV), each with distinct AgrD variants.

Purpose of the Study:

  • To investigate the role of the putative peptidase MroQ in Staphylococcus aureus autoinducing peptide (AIP) production and maturation.
  • To determine if MroQ's function is conserved across all four Agr groups of S. aureus.

Main Methods:

  • Analysis of a ΔmroQ mutant for defects in AIP production and processing.
  • Complementation studies using isogenic Δagr and Δagr ΔmroQ strains with Agr-I to -IV systems.
  • In vivo validation using mouse skin infection models.

Main Results:

  • MroQ is essential for the maturation of AgrD-I, preventing the accumulation of processing intermediates and ensuring secreted mature AIP.
  • MroQ is required for AIP maturation and activity in Agr-I, -II, and -IV strains, but not in Agr-III strains.
  • Experimental data confirmed MroQ's critical role in generating active AIP-I, -II, and -IV, with implications for bacterial virulence.

Conclusions:

  • MroQ acts as a key mediator in the maturation of cyclic autoinducing peptides in Staphylococcus aureus.
  • The function of MroQ in AIP maturation is essential for Agr-I, -II, and -IV strains, highlighting its significance in S. aureus pathogenesis.
  • MroQ's specific requirement for certain Agr groups underscores the diversity within the Agr system's regulatory mechanisms.
Keywords:
AgrMroQStaphylococcus aureuspeptidasepeptidepheromonequorum sensingskin infectionvirulence

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