Regulation of Staphylococcus aureus Virulence

Abstract

Staphylococcus aureus is a Gram-positive opportunistic pathogen that has evolved a complex regulatory network to control virulence. One of the main functions of this interconnected network is to sense various environmental cues and respond by altering the production of virulence factors necessary for survival in the host, including cell surface adhesins and extracellular enzymes and toxins. Of these S. aureus regulatory systems, one of the best studied is the accessory gene regulator (agr), which is a quorum-sensing system that senses the local concentration of a cyclic peptide signaling molecule. This system allows S. aureus to sense its own population density and translate this information into a specific gene expression pattern. Besides agr, this pathogen uses other two-component systems to sense specific cues, and coordinates responses with cytoplasmic regulators of the SarA protein family and alternative sigma factors. These divergent regulatory systems integrate the various environmental and host-derived signals into a network that assures optimal pathogen response to the changing conditions. This chapter gives an overview of the most important and best studied S. aureus regulatory systems and summarizes the function of these regulators during host interactions. The regulatory systems discussed include the agr quorum-sensing system, the SaeRS, SrrAB and ArlRS two-component systems, the cytoplasmic SarA-family regulators (SarA, Rot and MgrA), and finally the alternative sigma factors (SigB and SigH).

Acapsular Staphylococcus aureus with a non-functional agr regains capsule expression after passage through the bloodstream in a bacteremia mouse model

“…Staphylococcus aureus possesses an intricate regulatory system that governs the production of soluble virulence factors and exoenzymes. In addition to Agr, main regulators include a number of two-component systems, such as SaeRS, transcriptional factors 33 , such as SarA and its homologues 34 and factor σB (sigB) 35 . Bioinformatic analysis of strains HU-14 and P3.1 sequences revealed that the sequences of the aforementioned regulators were conserved, with no differences between the parental strain and the derivative.…”

“…Since it was recently demonstrated that CP production is up regulated by SigB we focused our attention on this regulator 36 . The SigB regulon is known to respond to different stress signals and accordingly regulates stress responses 33 . One of the marker genes upregulated by SigB is asp23 37 .…”

Steroid Derivatives as Potential Antimicrobial Agents against Staphylococcus aureus Planktonic Cells

“…To investigate the anti-virulence activity of PYED-1 the expression levels of known S. aureus virulence and regulatory genes [24] were investigated by qRT-PCR (Table 5). RNA was extracted from exponential S. aureus cells (5 × 10 8 CFU/mL) untreated and treated at sub-MIC concentration (4 µg/mL) of PYED-1 for 3 h. No growth differences between treated and untreated cells were observed.…”

The Antibacterial Activity of Lavender Essential Oil Alone and In Combination with Octenidine Dihydrochloride against MRSA Strains

“…Staphylococcus aureus is a commensal bacterium that can colonize the skin and the mucoses of humans, but is also a pathogenic microorganism responsible for many types of infections. The pathogenicity of this bacterium is primarily associated with the variety of virulence factors like enzymes and toxins [1]. Virulence factors combined with the efficient evasion mechanisms make S. aureus a formidable opponent.…”