Staphylococcus epidermidis is the most frequent cause of nosocomial sepsis and catheter-related infections, in which biofilm formation considered to be main virulence mechanism. Quorum-sensing systems have been recognized as important regulators many bacteria. There a single quorum-sensing system S. encoded by agr operon. To investigate control formation, we constructed an deletion mutant, assayed for different stages determined agr-dependent regulation factors. The mutant showed increased...

Pathogens are exposed to different temperatures during an infection cycle and must regulate gene expression accordingly. However, the extent which virulent bacteria alter in response encountered host is unknown. Group A Streptococcus (GAS) a human-specific pathogen that responsible for illnesses ranging from superficial skin infections pharyngitis severe invasive such as necrotizing fasciitis streptococcal toxic shock syndrome. GAS survives multiplies at human infection. DNA microarray...

More than 200 direct CodY target genes in Staphylococcus aureus were identified by genome-wide analysis of vitro DNA binding. This analysis, which was confirmed for some DNase I footprinting assays, revealed that is a regulator numerous transcription units associated with amino acid biosynthesis, transport macromolecules, and virulence. The virulence regulated fell into three groups. One group dependent on the Agr system its expression; these indirectly through repression agr locus. A second...

ABSTRACT Staphylococcus aureus preferentially catabolizes glucose, generating pyruvate, which is subsequently oxidized to acetate under aerobic growth conditions. Catabolite repression of the tricarboxylic acid (TCA) cycle results in accumulation acetate. TCA derepression coincides with exit from exponential phase, onset catabolism, and maximal expression secreted virulence factors. These data suggest that carbon energy for post-exponential-phase factor production are derived catabolism...

ABSTRACT CodY is a global regulatory protein that was first discovered in Bacillus subtilis , where it couples gene expression to changes the pools of critical metabolites through its activation by GTP and branched-chain amino acids. Homologs can be found encoded genomes nearly all low-G+C gram-positive bacteria, including Staphylococcus aureus . The introduction codY -null mutation into two S. clinical isolates, SA564 UAMS-1, allelic replacement, resulted overexpression several virulence...

We describe the genome sequence of a macrolide-resistant strain (MGAS10394) serotype M6 group A Streptococcus (GAS). The is 1,900,156 bp in length, and 8 prophage-like elements or remnants compose 12.4% chromosome. 8.3-kb prophage remnant encodes SpeA4 variant streptococcal pyrogenic exotoxin A. MGAS10394 contains chimeric genetic element composed genes transposon encoding mefA gene conferring macrolide resistance. This also has novel surface-exposed protein (designated “R6 protein”), with...

Recently, we observed that Staphylococcus aureus strains newly isolated from patients had twofold-higher aconitase activity than a strain passaged extensively in vitro, leading us to hypothesize specific decreases over time during vitro passage. To test this hypothesis, recovered patient with toxic shock syndrome was serially for 6 weeks, and the measured. Aconitase decreased 38% (P < 0.001) by sixth week culture. During serial passage, S. existed as heterogeneous population two colony types...

Staphylococcus aureus and epidermidis are the leading causes of nosocomial infections in United States often associated with biofilms attached to indwelling medical devices. Despite importance biofilms, there is very little consensus about metabolic requirements S. during biofilm growth. To assess growing a biofilm, we grew USA200 USA300 clonal types flow cells measured extraction accumulation metabolites. In spite genetic differences, both extracted glucose accumulated lactate, acetate,...

ABSTRACT Recently, we reported that the prototypical Staphylococcus aureus strain RN6390 (a derivative of NCTC 8325) had significantly reduced aconitase activity relative to a diverse group S. isolates, leading hypothesis has impaired tricarboxylic acid (TCA) cycle-mediated acetate catabolism. Analysis culture supernatant from confirmed was incompletely catabolized, suggesting ability catabolize can be lost by . To test this hypothesis, examined carbon catabolism strains whose genome...

ABSTRACT In bacteria, translation initiates with formyl-methionine; however, the N-terminal formyl group is usually removed by peptide deformylase, an enzymatic activity requiring iron. Staphylococcus aureus δ-toxin a 26-amino-acid polypeptide secreted predominantly formylated methionine, which led us to investigate regulation of deformylation. We observed that during exponential and early postexponential growth, accumulated in culture medium deformylated forms. contrast, only after phase....

ABSTRACT Staphylococcal polysaccharide intercellular adhesin (PIA) is important for the development of a mature biofilm. PIA production increased during growth in nutrient-replete or iron-limited medium and under conditions low oxygen availability. Additionally, stress-inducing stimuli such as heat, ethanol, high concentrations salt increase PIA. These same environmental are known to repress tricarboxylic acid (TCA) cycle activity, leading us hypothesize that altering TCA activity would...

The ability of Staphylococcus aureus to adapt various conditions stress is the result a complex regulatory response. Previously, it has been demonstrated that Clp homologues are important for variety conditions, and our laboratory shown clpC homologue was highly expressed in S. strain DSM20231 during biofilm formation relative expression planktonic cells. Persistence long-term survival hallmark biofilm-associated staphylococcal infections, as cure frequently fails even presence bactericidal...

ABSTRACT Staphylococcus epidermidis is a major nosocomial pathogen primarily infecting immunocompromised individuals or those with implanted biomaterials (e.g., catheters). Biomaterial-associated infections often involve the formation of biofilm on surface medical device. In S. , polysaccharide intercellular adhesin (PIA) an important mediator and pathogenesis. Synthesis PIA regulated by at least three DNA binding proteins (IcaR, SarA, σ B ) several environmental nutritional conditions....

ABSTRACT Staphylococci are the leading causes of endovascular infections worldwide. Commonly, these involve formation biofilms on surface biomaterials. Biofilms a complex aggregation bacteria commonly encapsulated by an adhesive exopolysaccharide matrix. In staphylococci, this matrix is composed polysaccharide intercellular adhesin (PIA). PIA synthesized when tricarboxylic acid (TCA) cycle repressed. The inverse correlation between synthesis and TCA activity led us to hypothesize that...

Bacterial cultivation requires consideration of three things: The bacterial strain, medium, and conditions. Most microbiologists dutifully report their choice strains media in manuscripts; however, these same often overlook reporting Without this information, it is difficult to determine if cultures were grown aerobically, microaerobically, or anaerobically. To cultivate bacteria necessary understand that oxygen does not readily diffuse into culture media; needs help get in. Microbiologists...

ABSTRACT Staphylococcus aureus is a major cause of nosocomial and community-acquired infections. The success S. as pathogen due in part to its many virulence determinants resistance antimicrobials. In particular, methicillin-resistant has emerged infections led increased use the antibiotics vancomycin daptomycin, which isolation vancomycin-intermediate daptomycin-nonsusceptible strains. most common mechanism by acquires intermediate adapting physiology metabolism permit growth presence these...

Staphylococcus epidermidis is an opportunistic bacterium whose infections often involve the formation of a biofilm on implanted biomaterials. In S. epidermidis, exopolysaccharide facilitating bacterial adherence in polysaccharide intercellular adhesin (PIA), synthesis requires enzymes encoded within operon (icaADBC). vitro, biofilms enhanced by conditions that repress tricarboxylic acid (TCA) cycle activity, such as growth medium containing glucose. many Gram-positive bacteria, repression...

ABSTRACT Staphylococcus aureus is a prominent nosocomial pathogen and major cause of biomaterial-associated infections. The success S. as due in part to its ability adapt stressful environments. As an example, the transition from residing nares blood or deeper tissues accompanied by changes availability nutrients elements such oxygen iron. such, nutrients, oxygen, iron are important determinants virulence factor synthesis . In addition influencing synthesis, critical cofactors enzymatic...

ABSTRACT A recent controversial hypothesis suggested that the bactericidal action of antibiotics is due to generation endogenous reactive oxygen species (ROS), a process requiring citric acid cycle (tricarboxylic [TCA] cycle). To test this hypothesis, we assessed ability oxacillin induce ROS production and cell death in Staphylococcus epidermidis strain 1457 an isogenic mutant. Our results confirm contributory role for TCA-dependent enhancing susceptibility S. toward β-lactam also revealed...

Streptococcus pyogenes is a human-specific pathogen that relies on its host for metabolic substrates. Rgg-like proteins constitute family of transcriptional regulators present in several gram-positive bacteria. In S. pyogenes, Rgg influences the expression virulence-associated localized to cell wall and extracellular environment. Secreted enzymes may degrade macromolecules, thereby liberating To determine if regulation exoprotein associated with altered metabolism, catabolic activities...

Abstract Human polymorphonuclear leukocytes (PMNs) are an essential part of innate immunity and contribute significantly to inflammation. Although much is nderstood about the inflammatory response, molecular basis for termination inflammation in humans largely undefined. We used human oligonucleotide microarrays identify genes differentially regulated during onset apoptosis occurring after PMN phagocytosis. Genes encoding proteins that regulate cell metabolism vesicle trafficking comprised...

We previously hypothesized that Staphylococcus epidermidis senses a diverse set of environmental and nutritional factors associated with biofilm formation through modulation in the activity tricarboxylic acid (TCA) cycle. Herein, we report our further investigation impact additional stress on TCA cycle provide detailed description NMR methodology. S. wild-type strain 1457 was treated stressors are formation, sublethal dose tetracycline, 5% NaCl, 2% glucose, autoinducer-2 (AI-2). As controls...