Corneal virulence of Staphylococcus aureus: roles of alpha-toxin and protein A in pathogenesis.

ABSTRACT The virulence determinants of Staphylococcus aureus are coordinately controlled by several unlinked chromosomal loci. Here, we report the identification of CYL5614, derived from strain Becker, with a mutation that affects the expression of type 8 capsular polysaccharide (CP8), nuclease, alpha-toxin, coagulase, protease, and protein A. This novel locus, named mgr, was linked by transposon Tn917 and mapped by three-factorial transduction crosses. The region containing the mgr locus was cloned and sequenced. Deletion mutagenesis and genetic complementation showed that the locus consisted of one gene, mgrA. Interestingly, mgrA-null mutants exhibited a phenotype opposite to that of CYL5614. This was due to a T-to-C mutation upstream of mgrA that resulted in a four- to eightfold increase in mgrA transcription in strain CYL5614. Thus, these results indicate that mgrA is an activator of CP8 and nuclease but a repressor of alpha-toxin, coagulase, protease, and protein A. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed that the mgr locus profoundly affected extracellular protein production, suggesting that the locus may regulate many other genes as well. The translated MgrA protein has a region of significant homology, which includes the helix-turn-helix DNA-binding motif, with the Escherichia coli MarR family of transcriptional regulators. Northern slot blot analyses suggested that mgr affected CP8, alpha-toxin, nuclease, and protein A at the transcriptional level.

Download Full-text

Virulence of protein A-deficient and alpha-toxin-deficient mutants of Staphylococcus aureus isolated by allele replacement.

Infection and Immunity ◽

10.1128/iai.55.12.3103-3110.1987 ◽

1987 ◽

Vol 55 (12) ◽

pp. 3103-3110 ◽

Cited By ~ 171

Author(s):

A H Patel ◽

P Nowlan ◽

E D Weavers ◽

T Foster

Keyword(s):

Staphylococcus Aureus ◽

Protein A ◽

Alpha Toxin ◽

Allele Replacement

Download Full-text

Regulation of agr-Dependent Virulence Genes in Staphylococcus aureus by RNAIII from Coagulase-Negative Staphylococci

Journal of Bacteriology ◽

10.1128/jb.180.12.3181-3186.1998 ◽

1998 ◽

Vol 180 (12) ◽

pp. 3181-3186 ◽

Cited By ~ 57

Author(s):

Karin Tegmark ◽

Eva Morfeldt ◽

Staffan Arvidson

Keyword(s):

Staphylococcus Aureus ◽

Cell Surface ◽

Serine Protease ◽

Protein A ◽

Surface Proteins ◽

Open Reading Frames ◽

Alpha Toxin ◽

Coagulase Negative Staphylococci ◽

Cell Surface Proteins ◽

Genes Encoding

ABSTRACT Many of the genes coding for extracellular toxins, enzymes, and cell surface proteins in Staphylococcus aureus are regulated by a 510-nucleotide (nt) RNA molecule, RNAIII. Transcription of genes encoding secreted toxins and enzymes, includinghla (alpha-toxin), saeB (enterotoxin B),tst (toxic shock syndrome toxin 1), and ssp(serine protease), is stimulated, while transcription of genes encoding cell surface proteins, like spa (protein A) andfnb (fibronectin binding proteins), is repressed. Besides being a regulator, RNAIII is also an mRNA coding for staphylococcal delta-lysin. We have identified RNAIII homologs in three different coagulase-negative staphylococci (CoNS), i.e., Staphylococcus epidermidis, Staphylococcus simulans, andStaphylococcus warneri. RNAIII from these CoNS turned out to be very similar to that of S. aureus and contained open reading frames encoding delta-lysin homologs. Though a number of big insertions and/or deletions have occurred, mainly in the 5′ half of the molecules, the sequences show a high degree of identity, especially in the first 50 and last 150 nt. The CoNS RNAIII had the ability to completely repress transcription of protein A in an RNAIII-deficientS. aureus mutant and the ability to stimulate transcription of the alpha-toxin and serine protease genes. However, the stimulatory effect was impaired compared to that of S. aureus RNAIII, suggesting that these regulatory functions are independent. By creating S. epidermidis-S. aureus RNAIII hybrids, we could also show that both the 5′ and 3′ halves of the RNAIII molecule are involved in the transcriptional regulation of alpha-toxin and serine protease mRNAs in S. aureus.

Download Full-text

Nicotiana spp. for the Expression and Purification of Functional IgG3 Antibodies Directed Against the Staphylococcus aureus Alpha Toxin

Frontiers in Chemical Engineering ◽

10.3389/fceng.2021.737010 ◽

2021 ◽

Vol 3 ◽

Author(s):

P. Opdensteinen ◽

S. Meyer ◽

J. F. Buyel

Keyword(s):

Staphylococcus Aureus ◽

Binding Capacity ◽

Protein A ◽

Adaptive Immune Response ◽

Hybridoma Cells ◽

Alpha Toxin ◽

In Planta ◽

Affinity Ligand ◽

Igg3 Subclass ◽

Drug Resistant Strains

Immunoglobulin subclass IgG1 is bound and neutralized effectively by Staphylococcus aureus protein A, allowing the bacterium to evade the host’s adaptive immune response. In contrast, the IgG3 subclass is not bound by protein A and can be used to treat S. aureus infections, including drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). However, the yields of recombinant IgG3 are generally low because this subclass is prone to degradation, and recovery is hindered by the inability to use protein A as an affinity ligand for antibody purification. Here, we investigated plants (Nicotiana spp.) as an alternative to microbes and mammalian cell cultures for the production of an IgG3 antibody specific for the S. aureus alpha toxin. We targeted recombinant IgG3 to different subcellular compartments and tested different chromatography conditions to improve recovery and purification. Finally, we tested the antigen-binding capacity of the purified antibodies. The highest IgG3 levels in planta (>130 mg kg−1 wet biomass) were achieved by targeting the endoplasmic reticulum or apoplast. Although the purity of IgG3 exceeded 95% following protein G chromatography, product recovery requires further improvement. Importantly, the binding affinity of the purified antibodies was in the nanomolar range and thus comparable to previous studies using murine hybridoma cells as the production system.

Download Full-text

O94 Recognition of Staphylococcus aureus by plasmacytoid dendritic cells is species-specific but not related to alpha-toxin or protein A expression

International Journal of Antimicrobial Agents ◽

10.1016/s0924-8579(07)70063-8 ◽

2007 ◽

Vol 29 ◽

pp. S19

Author(s):

M. Parcina ◽

C. Wendt ◽

K. Heeg ◽

I.B. Bekeredjian-Ding

Keyword(s):

Staphylococcus Aureus ◽

Dendritic Cells ◽

Protein A ◽

Plasmacytoid Dendritic Cells ◽

Alpha Toxin ◽

Species Specific

Download Full-text

MsrR, a Putative Cell Envelope-Associated Element Involved in Staphylococcus aureus sarA Attenuation

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.8.2558-2564.2003 ◽

2003 ◽

Vol 47 (8) ◽

pp. 2558-2564 ◽

Cited By ~ 51

Author(s):

Jutta Rossi ◽

Markus Bischoff ◽

Akihito Wada ◽

Brigitte Berger-Bächi

Keyword(s):

Staphylococcus Aureus ◽

Virulence Factors ◽

Regulatory Network ◽

Cell Envelope ◽

Protein A ◽

Virulence Gene ◽

Exponential Growth Phase ◽

Alpha Toxin ◽

Altered Expression ◽

Virulence Gene Expression

ABSTRACT A novel membrane-associated protein, MsrR, was identified in Staphylococcus aureus which affects resistance to methicillin and teicoplanin, as well as the synthesis of virulence factors. MsrR belongs to the LytR-CpsA-Psr family of cell envelope-related transcriptional attenuators and was shown to be inducible by cell wall-active agents, such as β-lactams, glycopeptides, and lysostaphin. The expression of msrR peaked in the early exponential growth phase and decreased sharply thereafter. msrR mutants showed increased sarA transcription and an earlier and higher expression of RNAIII, resulting in altered expression of virulence factors such as alpha-toxin and protein A. These observations suggest that MsrR is a new component involved in sarA attenuation and the regulatory network controlling virulence gene expression in S. aureus.

Download Full-text

XerC Contributes to Diverse Forms of Staphylococcus aureus Infection viaagr-Dependent andagr-Independent Pathways

Infection and Immunity ◽

10.1128/iai.01462-15 ◽

2016 ◽

Vol 84 (4) ◽

pp. 1214-1225 ◽

Cited By ~ 9

Author(s):

Danielle N. Atwood ◽

Karen E. Beenken ◽

Allister J. Loughran ◽

Daniel G. Meeker ◽

Tamara L. Lantz ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Biofilm Formation ◽

Protein A ◽

Limited Capacity ◽

Alpha Toxin ◽

Extracellular Proteases ◽

Internal Organs ◽

Content Type ◽

Aureus Infection

We demonstrate that mutation ofxerC, which reportedly encodes a homologue of anEscherichia colirecombinase, limits biofilm formation in the methicillin-resistantStaphylococcus aureusstrain LAC and the methicillin-sensitive strain UAMS-1. This was not due to the decreased production of the polysaccharide intracellular adhesin (PIA) in either strain because the amount of PIA was increased in a UAMS-1xerCmutant and undetectable in both LAC and its isogenicxerCmutant. Mutation ofxerCalso resulted in the increased production of extracellular proteases and nucleases in both LAC and UAMS-1, and limiting the production of either class of enzymes increased biofilm formation in the isogenicxerCmutants. More importantly, the limited capacity to form a biofilm was correlated with increased antibiotic susceptibility in both strains in the context of an established biofilmin vivo. Mutation ofxerCalso attenuated virulence in a murine bacteremia model, as assessed on the basis of the bacterial loads in internal organs and overall lethality. It also resulted in the decreased accumulation of alpha toxin and the increased accumulation of protein A. These findings suggest thatxerCmay impact the functional status ofagr. This was confirmed by demonstrating the reduced accumulation of RNAIII and AgrA in LAC and UAMS-1xerCmutants. However, this cannot account for the biofilm-deficient phenotype ofxerCmutants because mutation ofagrdid not limit biofilm formation in either strain. These results demonstrate thatxerCcontributes to biofilm-associated infections and acute bacteremia and that this is likely due toagr-independent and -dependent pathways, respectively.

Download Full-text