scholarly journals Roles of the Site 2 Protease Eep in Staphylococcus aureus

2020 ◽  
Vol 202 (15) ◽  
Author(s):  
Danhong Cheng ◽  
Huiying Lv ◽  
Yong Yao ◽  
Sen Cheng ◽  
Qian Huang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Drug Resistance ◽  
Sex Pheromone ◽  
Enterococcus Faecalis ◽  
Surface Proteins ◽  
Signal Peptidase ◽  
Future Research ◽  
Human Neutrophils ◽  
Bacterial Survival ◽  
Content Type

ABSTRACT In Enterococcus faecalis, the site 2 protease Eep generates sex pheromones, including cAM373. Intriguingly, in Staphylococcus aureus, a peptide similar to cAM373, named cAM373_SA, is produced from the camS gene. Here, we report that the staphylococcal Eep homolog is not only responsible for the production of cAM373_SA but also critical for staphylococcal virulence. As with other Eep proteins, the staphylococcal Eep protein has four transmembrane (TM) domains, with the predicted zinc metalloprotease active site (HEXXH) in the first TM domain. eep deletion reduced the cAM373_SA activity in the culture supernatant to the level of the camS deletion mutant. It also markedly decreased the cAM373 peptide peak in a high-performance liquid chromatography (HPLC) analysis. Proteomics analysis showed that Eep affects the production and/or the release of diverse proteins, including the signal peptidase subunit SpsB and the surface proteins SpA, SasG, and FnbA. eep deletion decreased the adherence of S. aureus to host epithelial cells; however, the adherence of the eep mutant was increased by overexpression of the surface proteins SpA, SasG, and FnbA. eep deletion reduced staphylococcal resistance to killing by human neutrophils as well as survival in a murine model of blood infection. The overexpression of the surface protein SpA in the eep mutant increased bacterial survival in the liver. Our study illustrates that in S. aureus, Eep not only generates cAM373_SA but also contributes to the survival of the bacterial pathogen in the host. IMPORTANCE The emergence of multidrug-resistant Staphylococcus aureus makes the treatment of staphylococcal infections much more difficult. S. aureus can acquire a drug resistance gene from other bacteria, such as Enterococcus faecalis. Intriguingly, S. aureus produces a sex pheromone for the E. faecalis plasmid pAM373, raising the possibility that S. aureus actively promotes plasmid conjugation from E. faecalis. In this study, we found that the staphylococcal Eep protein is responsible for sex pheromone processing and contributes to the survival of the bacteria in the host. These results will enhance future research on the drug resistance acquisition of S. aureus and can lead to the development of novel antivirulence drugs.

scholarly journals Serine-Aspartate Repeat Protein D Increases Staphylococcus aureus Virulence and Survival in Blood

2016 ◽  
Vol 85 (1) ◽  
Author(s):  
Fatemeh Askarian ◽  
Satoshi Uchiyama ◽  
J. Andrés Valderrama ◽  
Clement Ajayi ◽  
Johanna U. E. Sollid ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Ex Vivo ◽  
Innate Immune ◽  
Human Neutrophils ◽  
Infection Model ◽  
Bacterial Survival ◽  
Bacterial Killing ◽  
Content Type ◽  
Repeat Protein

ABSTRACT Staphylococcus aureus expresses a panel of cell wall-anchored adhesins, including proteins belonging to the microbial surface components recognizing adhesive matrix molecule (MSCRAMM) family, exemplified by the serine-aspartate repeat protein D (SdrD), which serve key roles in colonization and infection. Deletion of sdrD from S. aureus subsp. aureus strain NCTC8325-4 attenuated bacterial survival in human whole blood ex vivo, which was associated with increased killing by human neutrophils. Remarkably, SdrD was able to inhibit innate immune-mediated bacterial killing independently of other S. aureus proteins, since addition of recombinant SdrD protein and heterologous expression of SdrD in Lactococcus lactis promoted bacterial survival in human blood. SdrD contributes to bacterial virulence in vivo, since fewer S. aureus subsp. aureus NCTC8325-4 ΔsdrD bacteria than bacteria of the parent strain were recovered from blood and several organs using a murine intravenous infection model. Collectively, our findings reveal a new property of SdrD as an important key contributor to S. aureus survival and the ability to escape the innate immune system in blood.

scholarly journals A Putative Cro-Like Repressor Contributes to Arylomycin Resistance in Staphylococcus aureus

2015 ◽  
Vol 59 (6) ◽  
pp. 3066-3074 ◽  
Author(s):  
Arryn Craney ◽  
Floyd E. Romesberg
Keyword(s):  
Staphylococcus Aureus ◽  
Ex Vivo ◽  
Transcriptional Regulator ◽  
Signal Peptidase ◽  
Health Concern ◽  
Resistant Bacteria ◽  
Type I ◽  
Wall Teichoic Acid ◽  
Content Type ◽  
Wide Range

ABSTRACTAntibiotic-resistant bacteria are a significant public health concern and motivate efforts to develop new classes of antibiotics. One such class of antibiotics is the arylomycins, which target type I signal peptidase (SPase), the enzyme responsible for the release of secreted proteins from their N-terminal leader sequences. Despite the essentiality, conservation, and relative accessibility of SPase, the activity of the arylomycins is limited against some bacteria, including the important human pathogenStaphylococcus aureus. To understand the origins of the limited activity againstS. aureus, we characterized the susceptibility of a panel of strains to two arylomycin derivatives, arylomycin A-C16and its more potent analog arylomycin M131. We observed a wide range of susceptibilities to the two arylomycins and found that resistant strains were sensitized by cotreatment with tunicamycin, which inhibits the first step of wall teichoic acid synthesis. To further understand howS. aureusresponds to the arylomycins, we profiled the transcriptional response ofS. aureusNCTC 8325 to growth-inhibitory concentrations of arylomycin M131 and found that it upregulates the cell wall stress stimulon (CWSS) and an operon consisting of a putative transcriptional regulator and three hypothetical proteins. Interestingly, we found that mutations in the putative transcriptional regulator are correlated with resistance, and selection for resistanceex vivodemonstrated that mutations in this gene are sufficient for resistance. The results begin to elucidate howS. aureuscopes with secretion stress and how it evolves resistance to the inhibition of SPase.

scholarly journals Disarming Pore-Forming Toxins with Biomimetic Nanosponges in Intraocular Infections

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Phillip S. Coburn ◽  
Frederick C. Miller ◽  
Austin L. LaGrow ◽  
Craig Land ◽  
Huzzatul Mursalin ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Bacillus Cereus ◽  
Enterococcus Faecalis ◽  
Vision Loss ◽  
Retinal Function ◽  
Bacterial Invasion ◽  
Methicillin Resistant ◽  
Content Type ◽  
Ocular Pathology

ABSTRACTIntraocular infections are prevalent after traumatic injuries or after common ocular surgeries. Infections cause inflammation that can damage the retina and architecture of the eye, often resulting in poor visual outcomes. Severe cases may result in blindness or require enucleation of the eye. Treatments for intraocular infections include intravitreal antibiotics and corticosteroids or surgical vitrectomy in serious cases. The increase in multidrug-resistant infections calls for novel treatment options. In the present study, a biomimetic erythrocyte-derived nanosponge was tested for the ability to neutralize pore-forming toxins from the most frequent Gram-positive bacterial causes of intraocular infections (Staphylococcus aureus,Enterococcus faecalis,Streptococcus pneumoniae, andBacillus cereus). Nanosponge pretreatment of supernatants reduced hemolytic activityin vitro.In a murine sterile endophthalmitis model, nanosponge pretreatment of injected supernatants resulted in greater retinal function and less ocular pathology compared to that in eyes injected with untreated supernatants from all pathogens except methicillin-resistantS. aureus. In a murine bacterial endophthalmitis model, treatment with gatifloxacin and gatifloxacin-nanosponges reduced intraocular bacterial burdens, except in the case of methicillin-sensitiveS. aureus. For all pathogens, eyes in both treatment groups showed decreased ocular pathology and inflammation. Overall, reductions in retinal function loss afforded by gatifloxacin-nanosponge treatment were significant forE. faecalis,S. pneumoniae, and methicillin-resistantS. aureusbut not forB. cereusand methicillin-sensitiveS. aureus. These results suggest that clinical improvements in intraocular infections following nanosponge treatment were dependent on the complexity and types of toxins produced. Nanosponges might serve as an adjunctive therapy for the treatment of ocular infections.IMPORTANCEEndophthalmitis is a blinding consequence of bacterial invasion of the interior of the eye. Because of increases in the numbers of ocular surgeries and intraocular injections, the incidence of endophthalmitis is steadily increasing.Staphylococcus aureus,Enterococcus faecalis,Streptococcus pneumoniae, andBacillus cereusare leading causes of infection following ocular procedures and trauma and are increasingly more difficult to treat due to multidrug resistance. Each of these pathogens produces pore-forming toxins that contribute to the pathogenesis of endophthalmitis. Treatment of these infections with antibiotics alone is insufficient to prevent damage to the retina and vision loss. Therefore, novel therapeutics are needed that include agents that neutralize bacterial pore-forming toxins. Here, we demonstrate that biomimetic nanosponges neutralize pore-forming toxins from these ocular pathogens and aid in preserving retinal function. Nanosponges may represent a new form of adjunct antitoxin therapy for serious potentially blinding intraocular infections.

scholarly journals Three-Dimensional In Vitro Staphylococcus aureus Abscess Communities Display Antibiotic Tolerance and Protection from Neutrophil Clearance

2020 ◽  
Vol 88 (11) ◽  
Author(s):  
Marloes I. Hofstee ◽  
Martijn Riool ◽  
Igors Terjajevs ◽  
Keith Thompson ◽  
Martin J. Stoddart ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Cells ◽  
Early Stage ◽  
Three Dimensional ◽  
Collagen Gel ◽  
Maximum Size ◽  
Human Neutrophils ◽  
Content Type

ABSTRACT Staphylococcus aureus is a prominent human pathogen in bone and soft-tissue infections. Pathophysiology involves abscess formation, which consists of central staphylococcal abscess communities (SACs), surrounded by a fibrin pseudocapsule and infiltrating immune cells. Protection against the ingress of immune cells such as neutrophils, or tolerance to antibiotics, remains largely unknown for SACs and is limited by the lack of availability of in vitro models. We describe a three-dimensional in vitro model of SACs grown in a human plasma-supplemented collagen gel. The in vitro SACs reached their maximum size by 24 h and elaborated a fibrin pseudocapsule, as confirmed by electron and immunofluorescence microscopy. The in vitro SACs tolerated 100× the MIC of gentamicin alone and in combination with rifampin, while planktonic controls and mechanically dispersed SACs were efficiently killed. To simulate a host response, SACs were exposed to differentiated PLB-985 neutrophil-like (dPLB) cells and to primary human neutrophils at an early stage of SAC formation or after maturation at 24 h. Both cell types were unable to clear mature in vitro SACs, but dPLB cells prevented SAC growth upon early exposure before pseudocapsule maturation. Neutrophil exposure after plasmin pretreatment of the SACs resulted in a significant decrease in the number of bacteria within the SACs. The in vitro SAC model mimics key in vivo features, offers a new tool to study host-pathogen interactions and drug efficacy assessment, and has revealed the functionality of the S. aureus pseudocapsule in protecting the bacteria from host phagocytic responses and antibiotics.

scholarly journals MgrA Negatively Impacts Staphylococcus aureus Invasion by Regulating Capsule and FnbA

2019 ◽  
Vol 87 (12) ◽  
Author(s):  
Mei G. Lei ◽  
Dereje D. Gudeta ◽  
Thanh T. Luong ◽  
Chia Y. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Hela Cells ◽  
Biological Significance ◽  
Surface Protein ◽  
Surface Proteins ◽  
Multiple Gene ◽  
Content Type ◽  
Fibronectin Binding Protein ◽  
Different Levels ◽  
Complex Regulatory Network

ABSTRACT Virulence genes are regulated by a complex regulatory network in Staphylococcus aureus. Some of the regulators are global in nature and affect many downstream genes. MgrA is a multiple-gene regulator that has been shown to activate genes involved in capsule biosynthesis and repress surface protein genes. The goal of this study was to demonstrate the biological significance of MgrA regulation of capsule and surface proteins. We found that strain Becker possessed one fibronectin-binding protein, FnbA, and that FnbA was the predominant protein involved in invasion of nonphagocytic HeLa cells. By genetic analysis of strains with different amounts of capsule, we demonstrated that capsule impeded invasion of HeLa cells by masking the bacterial cell wall-anchored protein FnbA. Using variants with different levels of mgrA transcription, we further demonstrated that MgrA negatively impacted invasion by activating the cap genes involved in capsule biosynthesis and repressing the fnbA gene. Thus, we conclude that MgrA negatively impacts cell invasion of S. aureus Becker by promoting capsule and repressing FnbA.

scholarly journals Role of Phenol-Soluble Modulins in Formation of Staphylococcus aureus Biofilms in Synovial Fluid

2015 ◽  
Vol 83 (7) ◽  
pp. 2966-2975 ◽  
Author(s):  
Sana S. Dastgheyb ◽  
Amer E. Villaruz ◽  
Katherine Y. Le ◽  
Vee Y. Tan ◽  
Anthony C. Duong ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Synovial Fluid ◽  
Antibiotic Treatment ◽  
Joint Infection ◽  
Regulatory System ◽  
Surface Proteins ◽  
Host Matrix ◽  
Content Type ◽  
Prosthetic Joint ◽  
Prosthetic Joint Infections

Staphylococcus aureusis a leading cause of prosthetic joint infections, which, as we recently showed, proceed with the involvement of biofilm-like clusters that cause recalcitrance to antibiotic treatment. Here we analyzed why these clusters grow extraordinarily large, reaching macroscopically visible extensions (>1 mm). We found that while specificS. aureussurface proteins are a prerequisite for agglomeration in synovial fluid, low activity of the Agr regulatory system and subsequent low production of the phenol-soluble modulin (PSM) surfactant peptides cause agglomerates to grow to exceptional dimensions. Our results indicate that PSMs function by disrupting interactions of biofilm matrix molecules, such as the polysaccharide intercellular adhesin (PIA), with the bacterial cell surface. Together, our findings support a two-step model of staphylococcal prosthetic joint infection: As we previously reported, interaction ofS. aureussurface proteins with host matrix proteins such as fibrin initiates agglomeration; our present results show that, thereafter, the bacterial agglomerates grow to extremely large sizes owing to the lack of PSM expression under the specific conditions present in joints. Our findings provide a mechanistic explanation for the reported extreme resistance of joint infection to antibiotic treatment, lend support to the notions that Agr functionality and PSM production play a major role in defining different forms ofS. aureusinfection, and have important implications for antistaphylococcal therapeutic strategies.

scholarly journals Children with Invasive Staphylococcus aureus Disease Exhibit a Potently Neutralizing Antibody Response to the Cytotoxin LukAB

2013 ◽  
Vol 82 (3) ◽  
pp. 1234-1242 ◽  
Author(s):  
Isaac P. Thomsen ◽  
Ashley L. DuMont ◽  
David B. A James ◽  
Pauline Yoong ◽  
Benjamin R. Saville ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibody Response ◽  
High Titer ◽  
Humoral Response ◽  
Neutralizing Antibody ◽  
Human Neutrophils ◽  
Serum Samples ◽  
Marked Rise ◽  
Content Type

ABSTRACTDespite the importance ofStaphylococcus aureusas a common invasive bacterial pathogen, the humoral response to infection remains inadequately defined, particularly in children. The purpose of this study was to assess the humoral response to extracellular staphylococcal virulence factors, including the bicomponent leukotoxins, which are critical for the cytotoxicity ofS. aureustoward human neutrophils. Children with culture-provenS. aureusinfection were prospectively enrolled and stratified by disease type. Fifty-three children were enrolled in the study, of which 90% had invasive disease. Serum samples were obtained during the acute (within 48 h) and convalescent (4 to 6 weeks postinfection) phases, at which point both IgG titers againstS. aureusexotoxins were determined, and the functionality of the generated antibodies was evaluated. Molecular characterization of clinical isolates was also performed. We observed a marked rise in antibody titer from acute-phase to convalescent-phase sera for LukAB, the most recently describedS. aureusbicomponent leukotoxin. LukAB production by the isolates was strongly correlated with cytotoxicityin vitro, and sera containing anti-LukAB antibodies potently neutralized cytotoxicity. Antibodies toS. aureusantigens were detectable in healthy pediatric controls but at much lower titers than in sera from infected subjects. The discovery of a high-titer, neutralizing antibody response to LukAB during invasive infections suggests that this toxin is producedin vivoand that it elicits a functional humoral response.

scholarly journals Iron-Mediated Control of Pseudomonas aeruginosa-Staphylococcus aureus Interactions in the Cystic Fibrosis Lung

2015 ◽  
Vol 197 (14) ◽  
pp. 2250-2251 ◽  
Author(s):  
Patricia M. Barnabie ◽  
Marvin Whiteley
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Patient Outcomes ◽  
Cystic Fibrosis Lung ◽  
Bacterial Survival ◽  
Content Type ◽  
Host Environment ◽  
Bacterial Interactions

Communication is an important factor for bacterial survival, growth, and persistence. Much work has examined both inter- and intraspecies interactions and their effects on virulence. Now, researchers have begun to explore the ways in which host-modulated factors can impact bacterial interactions and subsequently affect patient outcomes. In this issue, two papers discuss how the host environment alters interactions between the pathogensPseudomonas aeruginosaandStaphylococcus aureus, largely in the context of cystic fibrosis.

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