scholarly journals ClpC affects the intracellular survival capacity of Staphylococcus aureus in non-professional phagocytic cells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Gubesh Gunaratnam ◽  
Lorena Tuchscherr ◽  
Mohamed I. Elhawy ◽  
Ralph Bertram ◽  
Janina Eisenbeis ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Protein A ◽  
Intracellular Survival ◽  
Host Cells ◽  
Virulence Determinants ◽  
Phagocytic Cells ◽  
Survival Capacity ◽  
Shock Proteins ◽  
Mutant Cells

Abstract Invasion and persistence of bacteria within host cells requires that they adapt to life in an intracellular environment. This adaptation induces bacterial stress through events such as phagocytosis and enhanced nutrient-restriction. During stress, bacteria synthesize a family of proteins known as heat shock proteins (HSPs) to facilitate adaptation and survival. Previously, we determined the Staphylococcus aureus HSP ClpC temporally alters bacterial metabolism and persistence. This led us to hypothesize that ClpC might alter intracellular survival. Inactivation of clpC in S. aureus strain DSM20231 significantly enhanced long-term intracellular survival in human epithelial (HaCaT) and endothelial (EA.hy926) cell lines, without markedly affecting adhesion or invasion. This phenotype was similar across a genetically diverse collection of S. aureus isolates, and was influenced by the toxin/antitoxin encoding locus mazEF. Importantly, MazEF alters mRNA synthesis and/or stability of S. aureus virulence determinants, indicating ClpC may act through the mRNA modulatory activity of MazEF. Transcriptional analyses of total RNAs isolated from intracellular DSM20231 and isogenic clpC mutant cells identified alterations in transcription of α-toxin (hla), protein A (spa), and RNAIII, consistent with the hypothesis that ClpC negatively affects the intracellular survival of S. aureus in non-professional phagocytic cells, via modulation of MazEF and Agr.

scholarly journals Staphylococcus aureus CcpA Affects Virulence Determinant Production and Antibiotic Resistance

2006 ◽  
Vol 50 (4) ◽  
pp. 1183-1194 ◽  
Author(s):  
Kati Seidl ◽  
Martin Stucki ◽  
Martin Ruegg ◽  
Christiane Goerke ◽  
Christiane Wolz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Protein A ◽  
Virulence Gene ◽  
Exponential Growth Phase ◽  
Virulence Determinants ◽  
Resistance Level ◽  
Virulence Gene Expression ◽  
Oxacillin Resistance

ABSTRACT Carbon catabolite protein A (CcpA) is known to function as a major regulator of gene expression in different gram-positive organisms. Deletion of the ccpA homologue (saCOL1786) in Staphylococcus aureus was found to affect growth, glucose metabolization, and transcription of selected virulence determinants. In liquid culture, deletion of CcpA decreased the growth rate and yield; however, the effect was only transient during the exponential-growth phase as long as glucose was present in the medium. Depletion of glucose and production of lactate was delayed, while the level of excretion of acetate was less affected and was even higher in the mutant culture. On solid medium, in contrast, growth of the ΔccpA mutant resulted in smaller colonies containing a lower number of CFU per colony. Deletion of CcpA had an effect on the expression of important virulence factors of S. aureus by down-regulating RNAIII, the effector molecule of the agr locus, and altering the transcription patterns of hla, encoding α-hemolysin, and spa, encoding protein A. CcpA inactivation markedly reduced the oxacillin resistance levels in the highly methicillin-resistant S. aureus strain COLn and the teicoplanin resistance level in a glycopeptide-intermediate-resistant S. aureus strain. The presence of CcpA in the capsular polysaccharide serotype 5 (CP5)-producing strain Newman abolished capsule formation and decreased cap operon transcription in the presence of glucose. The staphylococcal CcpA thus not only is involved in the regulation of carbon metabolism but seems to function as a modulator of virulence gene expression as well.

scholarly journals Prevalence of Methicillin Resistant and Virulence Determinants in Clinical Isolates of Staphylococcus aureus

2018 ◽  
Vol 10 (1) ◽  
pp. 108-115
Author(s):  
Manjunath Chavadi ◽  
Rahul Narasanna ◽  
Ashajyothi Chavan ◽  
Ajay Kumar Oli ◽  
Chandrakanth Kelmani. R
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Morphology ◽  
Methicillin Resistance ◽  
Protein A ◽  
Clinical Isolates ◽  
Clinical Samples ◽  
Virulence Determinants ◽  
Methicillin Resistant ◽  
Alternative Medicines ◽  
Mrsa Strains

Introduction:Methicillin-resistantStaphylococcus aureus(MRSA) is the major threat that is a result of the uncontrolled use of antibiotics causing a huge loss in health, so understanding their prevalence is necessary as a public health measure.Objective:The aim of this study was to determine the prevalence of methicillin-resistant MRSA and virulence determinant among associatedS. aureusfrom the clinical samples obtained from various hospital and health care centers of the Gulbarga region in India.Materials and Methods:All the collected samples were subjected for the screening ofS. aureusand were further characterized by conventional and molecular methods including their antibiotic profiling. Further, the response of methicillin antibiotic on cell morphology was studied using scanning electron microscopy.Results:A total 126S. aureuswas isolated from the clinical samples which showed, 100% resistant to penicillin, 55.5% to oxacillin, 75.3% to ampicillin, 70.6% to streptomycin, 66.6% to gentamicin, 8.7% to vancomycin and 6.3% to teicoplanin. The selected MRSA strains were found to possessmecA(gene coding for penicillin-binding protein 2A) andfemA(factor essential for methicillin resistance)genetic determinants in their genome with virulence determinants such as Coagulase (coa) and the X region of the protein A (spa)gene. Further, the methicillin response in resistantS. aureusshowed to be enlarged and malformed on cell morphology.Conclusion:The molecular typing of clinical isolates ofS. aureusin this study was highly virulent and also resistant to methicillin; this will assist health professionals to control, exploration of alternative medicines and new approaches to combat Staphylococcal infections more efficiently by using targeted therapy.

scholarly journals mgr, a Novel Global Regulator in Staphylococcus aureus

2003 ◽  
Vol 185 (13) ◽  
pp. 3703-3710 ◽  
Author(s):  
Thanh T. Luong ◽  
Steven W. Newell ◽  
Chia Y. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Polyacrylamide Gel Electrophoresis ◽  
Protein A ◽  
Sodium Dodecyl ◽  
Binding Motif ◽  
Transcriptional Level ◽  
Virulence Determinants ◽  
Alpha Toxin ◽  
Extracellular Protein Production

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.

scholarly journals Genome-Wide Transposon Mutagenesis Indicates that Mycobacterium marinum Customizes Its Virulence Mechanisms for Survival and Replication in Different Hosts

2015 ◽  
Vol 83 (5) ◽  
pp. 1778-1788 ◽  
Author(s):  
Eveline M. Weerdenburg ◽  
Abdallah M. Abdallah ◽  
Farania Rangkuti ◽  
Moataz Abd El Ghany ◽  
Thomas D. Otto ◽  
...  
Keyword(s):  
Insertion Site ◽  
Mycobacterium Marinum ◽  
Host Cells ◽  
Intracellular Pathogens ◽  
Virulence Determinants ◽  
Phagocytic Cells ◽  
General Hypothesis ◽  
Content Type ◽  
Genome Wide ◽  
A Genome

The interaction of environmental bacteria with unicellular eukaryotes is generally considered a major driving force for the evolution of intracellular pathogens, allowing them to survive and replicate in phagocytic cells of vertebrate hosts. To test this hypothesis on a genome-wide level, we determined for the intracellular pathogenMycobacterium marinumwhether it uses conserved strategies to exploit host cells from both protozoan and vertebrate origin. Using transposon-directed insertion site sequencing (TraDIS), we determined differences in genetic requirements for survival and replication in phagocytic cells of organisms from different kingdoms. In line with the general hypothesis, we identified a number of general virulence mechanisms, including the type VII protein secretion system ESX-1, biosynthesis of polyketide lipids, and utilization of sterols. However, we were also able to show thatM. marinumcontains an even larger set of host-specific virulence determinants, including proteins involved in the modification of surface glycolipids and, surprisingly, the auxiliary proteins of the ESX-1 system. Several of these factors were in fact counterproductive in other hosts. Therefore,M. marinumcontains different sets of virulence factors that are tailored for specific hosts. Our data imply that although amoebae could function as a training ground for intracellular pathogens, they do not fully prepare pathogens for crossing species barriers.

scholarly journals Staphylococcus aureus vaccines: Deviating from the carol

2016 ◽  
Vol 213 (9) ◽  
pp. 1645-1653 ◽  
Author(s):  
Dominique Missiakas ◽  
Olaf Schneewind
Keyword(s):  
Staphylococcus Aureus ◽  
Protein A ◽  
Invasive Disease ◽  
Phagocytic Cells ◽  
Subunit Vaccines ◽  
Clinical Endpoints ◽  
Patients At Risk ◽  
Resistant Strains ◽  
Opsonophagocytic Killing ◽  
Drug Resistant Strains

Staphylococcus aureus, a commensal of the human nasopharynx and skin, also causes invasive disease, most frequently skin and soft tissue infections. Invasive disease caused by drug-resistant strains, designated MRSA (methicillin-resistant S. aureus), is associated with failure of antibiotic therapy and elevated mortality. Here we review polysaccharide-conjugate and subunit vaccines that were designed to prevent S. aureus infection in patients at risk of bacteremia or surgical wound infection but failed to reach their clinical endpoints. We also discuss vaccines with ongoing trials for combinations of polysaccharide-conjugates and subunits. S. aureus colonization and invasive disease are not associated with the development of protective immune responses, which is attributable to a large spectrum of immune evasion factors. Two evasive strategies, assembly of protective fibrin shields via coagulases and protein A–mediated B cell superantigen activity, are discussed as possible vaccine targets. Although correlates for protective immunity are not yet known, opsonophagocytic killing of staphylococci by phagocytic cells offers opportunities to establish such criteria.

scholarly journals Nonprofessional Phagocytic Cell Receptors Involved inStaphylococcus aureusInternalization

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Nayeli Alva-Murillo ◽  
Joel Edmundo López-Meza ◽  
Alejandra Ochoa-Zarzosa
Keyword(s):  
Staphylococcus Aureus ◽  
Host Cell ◽  
Soft Tissues ◽  
Scavenger Receptor ◽  
Host Cells ◽  
Phagocytic Cell ◽  
Phagocytic Cells ◽  
Cell Receptors ◽  
Life Threatening ◽  
Bacterial Effectors

Staphylococcus aureusis a successful human and animal pathogen. The majority of infections caused by this pathogen are life threatening, primarily becauseS. aureushas developed multiple evasion strategies, possesses intracellular persistence for long periods, and targets the skin and soft tissues. Therefore, it is very important to understand the mechanisms employed byS. aureusto colonize and proliferate in these cells. The aim of this review is to describe the recent discoveries concerning the host receptors of nonprofessional phagocytes involved inS. aureusinternalization. Most of the knowledge related to the interaction ofS. aureuswith its host cells has been described in professional phagocytic cells such as macrophages. Here, we showed that in nonprofessional phagocytes theα5β1 integrin host receptor, chaperons, and the scavenger receptor CD36 are the main receptors employed duringS. aureusinternalization. The characterization and identification of new bacterial effectors and the host cell receptors involved will undoubtedly lead to new discoveries with beneficial purposes.

scholarly journals Deciphering Additional Roles for the EF-Tu, l-Asparaginase II and OmpT Proteins of Shiga Toxin-Producing Escherichia coli

2020 ◽  
Vol 8 (8) ◽  
pp. 1184 ◽  
Author(s):  
Alexia N. Torres ◽  
Nayaret Chamorro-Veloso ◽  
Priscila Costa ◽  
Leandro Cádiz ◽  
Felipe Del Canto ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Shiga Toxin ◽  
Outer Membrane Proteins ◽  
Protein A ◽  
Subcellular Location ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Virulence Determinants ◽  
T Lymphocyte Proliferation

Shiga toxin-producing Escherichia coli (STEC) causes outbreaks and sporadic cases of gastroenteritis. STEC O157:H7 is the most clinically relevant serotype in the world. The major virulence determinants of STEC O157:H7 are the Shiga toxins and the locus of enterocyte effacement. However, several accessory virulence factors, mainly outer membrane proteins (OMPs) that interact with the host cells may contribute to the virulence of this pathogen. Previously, the elongation factor thermo unstable (EF-Tu), l-asparaginase II and OmpT proteins were identified as antigens in OMP extracts of STEC. The known subcellular location of EF-Tu and l-asparaginase II are the cytoplasm and periplasm, respectively. Therefore, we investigate whether these two proteins may localize on the surface of STEC and, if so, what roles they have at this site. On the other hand, the OmpT protein, a well characterized protease, has been described as participating in the adhesion of extraintestinal pathogenic E. coli strains. Thus, we investigate whether OmpT has this role in STEC. Our results show that the EF-Tu and l-asparaginase II are secreted by O157:H7 and may also localize on the surface of this bacterium. EF-Tu was identified in outer membrane vesicles (OMVs), suggesting it as a possible export mechanism for this protein. Notably, we found that l-asparaginase II secreted by O157:H7 inhibits T-lymphocyte proliferation, but the role of EF-Tu at the surface of this bacterium remains to be elucidated. In the case of OmpT, we show its participation in the adhesion of O157:H7 to human epithelial cells. Thus, this study extends the knowledge of the pathogenic mechanisms of STEC.

scholarly journals Decreased Amounts of Cell Wall-Associated Protein A and Fibronectin-Binding Proteins in Staphylococcus aureus sarA Mutants due to Up-Regulation of Extracellular Proteases

2001 ◽  
Vol 69 (8) ◽  
pp. 4742-4748 ◽  
Author(s):  
Anna Karlsson ◽  
Patricia Saravia-Otten ◽  
Karin Tegmark ◽  
Eva Morfeldt ◽  
Staffan Arvidson
Keyword(s):  
Staphylococcus Aureus ◽  
Protease Inhibitor ◽  
Serine Protease ◽  
Binding Proteins ◽  
Protein A ◽  
Fold Increase ◽  
Cysteine Proteases ◽  
Extracellular Proteases ◽  
Fibronectin Binding ◽  
Mutant Cells

ABSTRACT Data have been presented indicating that Staphylococcus aureus cell surface protein can be degraded by extracellular proteases produced by the same bacterium. We have found that insarA mutant cells, which produce high amounts of four major extracellular proteases (staphylococcal serine protease [V8 protease] [SspA], cysteine protease [SspB], aureolysin [metalloprotease] [Aur], and staphopain [Scp]), the levels of cell-bound fibronectin-binding proteins (FnBPs) and protein A were very low compared to those of wild-type cells, in spite of unaltered or increased transcription of the corresponding genes. Cultivation ofsarA mutant cells in the presence of the global protease inhibitor α2-macroglobulin resulted in a 16-fold increase in cell-bound FnBPs, indicating that extracellular proteases were responsible for the decreased amounts of FnBPs in sarAmutant cells. The protease inhibitor E64 had no effect on the level of FnBPs, indicating that cysteine proteases were not involved. Inactivation of either ssp or aur in the prototype S. aureus strain 8325-4 resulted in a threefold increase in the amount of cell-bound FnBPs. Inactivation of the same protease genes in a sarA mutant of 8325-4 resulted in a 10- to 20-fold increase in cell-bound protein A. As the serine protease requires aureolysin to be activated, it can thus be concluded that the serine protease is the most important protease in the release of cell-bound FnBPs and protein A.

scholarly journals Staphylococcus aureus Extracellular Vesicles: A Story of Toxicity and the Stress of 2020

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 75
Author(s):  
Xiaogang Wang ◽  
Paul F. Koffi ◽  
Olivia F. English ◽  
Jean C. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Extracellular Vesicles ◽  
Stress Responses ◽  
Cell Types ◽  
Biologically Active ◽  
Host Cells ◽  
Virulence Determinants ◽  
Subinhibitory Concentrations ◽  
Secretory System

Staphylococcus aureus generates and releases extracellular vesicles (EVs) that package cytosolic, cell-wall associated, and membrane proteins, as well as glycopolymers and exoproteins, including alpha hemolysin, leukocidins, phenol-soluble modulins, superantigens, and enzymes. S. aureus EVs, but not EVs from pore-forming toxin-deficient strains, were cytolytic for a variety of mammalian cell types, but EV internalization was not essential for cytotoxicity. Because S. aureus is subject to various environmental stresses during its encounters with the host during infection, we assessed how these exposures affected EV production in vitro. Staphylococci grown at 37 °C or 40 °C did not differ in EV production, but cultures incubated at 30 °C yielded more EVs when grown to the same optical density. S. aureus cultivated in the presence of oxidative stress, in iron-limited media, or with subinhibitory concentrations of ethanol, showed greater EV production as determined by protein yield and quantitative immunoblots. In contrast, hyperosmotic stress or subinhibitory concentrations of erythromycin reduced S. aureus EV yield. EVs represent a novel S. aureus secretory system that is affected by a variety of stress responses and allows the delivery of biologically active pore-forming toxins and other virulence determinants to host cells.

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