<i>Staphylococcus aureus</i>Capsular Polysaccharides

O'Riordan, Katherine; Lee, Jean C.

doi:10.1128/cmr.17.1.218-234.2004

Cited by 512 publications

(459 citation statements)

References 114 publications

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“…However, to date, no environmental cue has been reported to be mediated by ArlS. Several environmental factors, which include iron concentration, oxygen tension, carbon dioxide and growth media, have been reported to influence capsule production (Lee & Lee, 2006;O'Riordan & Lee, 2004). The environmental control of virulence gene expression in S. aureus is an understudied area.…”

Section: Discussionmentioning

confidence: 99%

“…The role of these capsules in S. aureus virulence has recently been investigated in different laboratories using molecularly characterized strains and different animal models. These studies provide compelling evidence that CP5 and CP8 are important antiphagocytic virulence factors (for reviews see Lee & Lee, 2006;O'Riordan & Lee, 2004). Additionally, staphylococcal capsule was recently implicated as one of the few extracellular factors required for virulence in Caenorhabditis elegans (Bae et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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The arl locus positively regulates Staphylococcus aureus type 5 capsule via an mgrA-dependent pathway

Luong

Lee

2006

Microbiology

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Most clinical Staphylococcus aureus strains produce either type 5 or type 8 capsular polysaccharides. The production of these capsules is influenced by various environmental factors. To study the regulation of capsule, Tn551 transposon mutagenesis and transcriptional reporter gene fusion were employed to identify several putative regulatory loci that influenced capsule gene expression. One of these, the arl locus, was chosen for further analysis. Tn551 was found to insert within the coding region (near the translational start site of the arlR gene). ArlR, along with ArlS, forms a two-component system that has been previously shown to affect autolysis and production of several secreted proteins. Phenotypic analyses of the arlR-specific mutant and gene fusion analyses showed that arlR activated capsule production at the transcriptional level. However, gel mobility shift assays did not support activation of the capsule genes by direct ArlR binding to the primary cap5 promoter region upstream of the operon. In contrast, it was found that arl activated mgrA, an activator for capsule production, whereas mgrA did not have a significant effect on arlR. Genetic studies supported the notion that arlR functions upstream of mgrA with respect to the regulation of capsule production, although gene fusion studies indicated that arl could also regulate capsule independently from mgrA. Collectively, the results suggest that arl positively regulates capsule production at the transcriptional level primarily through an mgrA-dependent pathway.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The arl locus positively regulates Staphylococcus aureus type 5 capsule via an mgrA-dependent pathway

Luong

Lee

2006

Microbiology

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“…The production of the capsule has been shown to play a major role in bacterial virulence during infection by facilitating the pathogen's survival inside the host as a way to escape phagocytosis (Karakawa et al, 1988;Thakker et al, 1998;Nanra et al, 2013). This is particularly important during the acute phase of certain types of infection, including bacteraemia Thakker et al, 1998;O'Riordan & Lee, 2004;Watts et al, 2005;Nilsson et al, 1997;Kampen et al, 2005). Several attempts have been made to produce an effective vaccine to protect individuals at risk of S. aureus infection.…”

Section: Introductionmentioning

confidence: 99%

“…The ability of this pathogen to cause such infections relies on its many virulence factors and their coordinated regulation (David & Daum, 2010;Lowy, 1998;Cheung et al, 2004;Bronner et al, 2004;Somerville & Proctor, 2009;Novick & Geisinger, 2008). One of the major virulence factors is the capsular polysaccharide (CP) (O'Riordan & Lee, 2004). The production of the capsule has been shown to play a major role in bacterial virulence during infection by facilitating the pathogen's survival inside the host as a way to escape phagocytosis (Karakawa et al, 1988;Thakker et al, 1998;Nanra et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

MsaB activates capsule production at the transcription level in Staphylococcus aureus

2016

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Staphylococcus aureus produces several virulence factors that allow it to cause a variety of infections. One of the major virulence factors is the capsule, which contributes to the survival of the pathogen within the host as a way to escape phagocytosis. The production of the capsular polysaccharide is encoded in a 16 gene operon, which is regulated in response to several environmental stimuli including nutrient availability. For instance, the capsule is produced in the late-and post-exponential growth phases, but not in the early-or mid-exponential growth phase. Several regulators are involved in capsule production, but the regulation of the cap operon is still poorly understood. In this study, we show that MsaB activates the cap operon by binding directly to a 10 bp repeat in the promoter region. We show that despite the fact that MsaB is expressed throughout four growth phases, it only activates capsule production in the late-and post-exponential growth phases. Furthermore, we find that MsaB does not bind to its target site in the early and mid-exponential growth phases. This correlates with decreased nutrient availability and capsule production. These data suggest either that MsaB binding ability changes in response to nutrients or that other cap operon regulators interfere with the binding of MsaB to its target site. This study increases our understanding of the regulation of capsule production and the mechanism of action of MsaB.

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“…Many virulence factors, such as enterotoxins, TSST-1, exfoliative toxins, serine proteases, haemolysins, leucocidins, and adhesins, have been identified in clinical isolates, demonstrating their association with clinical diseases in vitro and in vivo [12][13][14][15]. As shown in Figure 1, capsule or protease production resists some of the innate immune factors [16][17][18][19]. Chemotherapy is often used against S. aureus infections; however, the emergence of methicillin-resistant S. aureus (MRSA), which is resistant to β-lactam antibiotics and other chemotherapeutic agents, is a serious clinical problem [20,21].…”

Section: Introductionmentioning

confidence: 99%

Innate defences against methicillin‐resistant Staphylococcus aureus (MRSA) infection

Komatsuzawa

Ouhara

Yamada

et al. 2005

The Journal of Pathology

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The innate immune system is the primary defence against bacterial infection. Among the factors involved in innate defence, anti-microbial peptides produced by humans have recently attracted attention due to their relevance to some diseases and also to the development of new chemotherapeutic agents. Staphylococcus aureus is one of the major human pathogens, causing a variety of infections from suppurative disease to food poisoning. Methicillin-resistant S. aureus (MRSA) is a clinical problem and with the recent emergence of a vancomycin-resistant strain, this will pose serious problems in the near future. In investigating the molecular biology of S. aureus infections to develop new chemotherapeutic agents against MRSA infections, knowledge of the interaction of innate anti-microbial peptides with S. aureus is important. In vitro and in vivo experiments demonstrate that exposure of S. aureus to host cells can induce the anti-microbial peptides β-defensin-2 (hBD2), hBD3, and LL37/CAP18. The induction level of these peptides differs among strains, as does the susceptibility of the strains, with MRSA strains exhibiting lower susceptibility. In summary, the susceptibility of S. aureus strains, including MRSA strains, to components of the innate immune system varies, with the MRSA strains showing more resistance to both innate immune factors and chemotherapeutic agents.

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Staphylococcus aureusCapsular Polysaccharides

Cited by 512 publications

References 114 publications

The arl locus positively regulates Staphylococcus aureus type 5 capsule via an mgrA-dependent pathway

The arl locus positively regulates Staphylococcus aureus type 5 capsule via an mgrA-dependent pathway

MsaB activates capsule production at the transcription level in Staphylococcus aureus

Innate defences against methicillin‐resistant Staphylococcus aureus (MRSA) infection

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