Metabolically Stable Adenylation Inhibitors of Biotin Protein Ligase as Antibacterial Agents.

The antibacterial agent Bio-AMS is metabolized in vivo through hydrolysis of the central acyl-sulfamide linker leading to high clearance and release of a moderately cytotoxic metabolite . Herein, we disclose analogues designed to prevent the metabolism of the central acyl-sulfamide moiety through steric hindrance or attenuation of the acyl-sulfamide electrophilicity. was identified as a metabolically stable analogue with a single-digit nanomolar dissociation constant for biotin protein ligase (BPL) and minimum inhibitory concentrations (MICs) against and ranging from 0.

Phage-Encoded Virulence Factor, Gp05, Alters Membrane Phospholipids and Reduces Antimicrobial Susceptibility in Methicillin-Resistant Staphylococcus aureus.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a leading pathogen causing severe endovascular infections. The prophage-encoded protein Gp05 has been identified as a critical virulence factor that contributes to MRSA persistence during vancomycin (VAN) treatment in an experimental endocarditis model. However, the underlining mechanisms driving this persistence phenotype remain poorly understood.

GraS signaling in is regulated by a single D35 residue in the extracellular loop.

Bacterial two-component systems are crucial features of bacterial pathogens such as methicillin-resistant to overcome environmental and antimicrobial stresses by activating regulons to interfere with the bactericidal mechanisms. GraRS is a unique subset of two-component systems belonging to the intramembrane-sensing histidine kinase family (IM-HK) and is responsible for resistance to cationic host defense peptides. However, the precise manner by which the short 9-residue extracellular loop of the membrane sensor GraS detects the antimicrobial peptides and transduces the signal is not comprehensively understood.

Gp05, a Prophage-Encoded Virulence Factor, Contributes to Persistent Methicillin-Resistant Staphylococcus aureus Endovascular Infection.

Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections represent a serious public health threat. We recently demonstrated that the presence of a novel prophage ϕSA169 was associated with vancomycin (VAN) treatment failure in experimental MRSA endocarditis. In this study, we assessed the role of a ϕSA169 gene, ϕ80α_ (), in VAN-persistent outcome using isogenic MRSA strain sets.

Role of the NaHCO Transporter MpsABC in the NaHCO-β-Lactam-Responsive Phenotype in Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) infections are an increasing concern due to their intrinsic resistance to most standard-of-care β-lactam antibiotics. Recent studies of clinical isolates have documented a novel phenotype, termed NaHCO responsiveness, in which a substantial proportion of MRSA strains exhibit enhanced susceptibility to β-lactams such as cefazolin and oxacillin in the presence of NaHCO. A bicarbonate transporter, MpsAB (embrane otential-generating ystem), was recently found in S.

Influence of Sodium Bicarbonate on Wall Teichoic Acid Synthesis and β-Lactam Sensitization in NaHCO-Responsive and Nonresponsive Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) strains pose major treatment challenges due to their innate resistance to most β-lactams under standard antimicrobial susceptibility testing conditions. A novel phenotype among MRSA, termed "NaHCO responsiveness," where certain strains display increased susceptibility to β-lactams in the presence of NaHCO, has been identified among a relatively large proportion of MRSA isolates. One underlying mechanism of NaHCO responsiveness appears to be related to decreased expression and altered functionality of several genes and proteins involved in cell wall synthesis and maturation.

Teg58, a small regulatory RNA, is involved in regulating arginine biosynthesis and biofilm formation in Staphylococcus aureus.

Staphylococcus aureus adapts to different environments by sensing and responding to diverse environmental cues. The responses are coordinately regulated by regulatory proteins, and small regulatory RNAs at the transcriptional and translational levels. Here, we characterized teg58, a SarA repressed sRNA, using ChIP-Seq and RNA-Seq analysis of a sarA mutant.

Regulation of neutrophil myeloperoxidase inhibitor SPIN by the small RNA Teg49 in Staphylococcus aureus.

Teg49 is a Staphylococcus aureus trans-acting regulatory sRNA derived from cleavage of the sarA P3 transcript. We showed by RNA-Seq here that the 5' trident-like structure in Teg49 regulates transcriptionally (direct and indirect) 22 genes distinct from sarA. Among these, Teg49 was noted to repress spn, encoding a 102 residue preprotein which yields the mature 73 residue peptide which inhibits the catalytic activity of myeloperoxidase in human neutrophils.

The NaHCO-Responsive Phenotype in Methicillin-Resistant Staphylococcus aureus (MRSA) Is Influenced by Genotype.

Methicillin-resistant Staphylococcus aureus (MRSA) strains are a leading cause of many invasive clinical syndromes, and pose treatment difficulties due to their resistance to most β-lactams on standard laboratory testing. A novel phenotype frequently identified in MRSA strains, termed 'NaHCO-responsiveness', is a property whereby strains are susceptible to many β-lactams in the presence of NaHCO. Specific genotypes, repression of /PBP2a expression and perturbed maturation of PBP2a by NaHCO have all been associated with this phenotype.

Impacts of NaHCO on β-Lactam Binding to PBP2a Protein Variants Associated with the NaHCO-Responsive versus NaHCO-Non-Responsive Phenotypes.

Methicillin-resistant (MRSA) regulates resistance to β-lactams via preferential production of an alternative penicillin-binding protein (PBP), PBP2a. PBP2a binds many β-lactam antibiotics with less affinity than PBPs which are predominant in methicillin-susceptible (MSSA) strains. A novel, rather frequent in vitro phenotype was recently identified among clinical MRSA bloodstream isolates, termed "NaHCO-responsiveness".

Expanding the Staphylococcus aureus SarA Regulon to Small RNAs.

SarA, a transcriptional regulator of Staphylococcus aureus, is a major global regulatory system that coordinates the expression of target genes involved in its pathogenicity. Various studies have identified a large number of SarA target genes, but an in-depth characterization of the regulon, including small regulatory RNAs (sRNAs), has not yet been done. In this study, we utilized transcriptome sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) to determine a comprehensive list of SarA-regulated targets, including both mRNAs and sRNAs.

The Enzymatic Activity of Inosine 5'-Monophosphate Dehydrogenase May Not Be a Vulnerable Target for Infections.

Many bacterial pathogens, including , require inosine 5'-monophosphate dehydrogenase (IMPDH) for infection, making this enzyme a promising new target for antibiotics. Although potent selective inhibitors of bacterial IMPDHs have been reported, relatively few have displayed antibacterial activity. Here we use structure-informed design to obtain inhibitors of IMPDH (IMPDH) that have potent antibacterial activity (minimal inhibitory concentrations less than 2 μM) and low cytotoxicity in mammalian cells.

CspA regulation of Staphylococcus aureus carotenoid levels and σ activity is controlled by YjbH and Spx.

Staphyloxanthin, a carotenoid in S. aureus, is a powerful antioxidant against oxidative stresses. The crtOPQMN operon driving pigment synthesis is under the control of σ .

Small RNA teg49 Is Derived from a Transcript and Regulates Virulence Genes Independent of SarA in Staphylococcus aureus.

Expression of virulence factors in is regulated by a wide range of transcriptional regulators, including proteins and small RNAs (sRNAs), at the level of transcription and/or translation. The locus consists of three overlapping transcripts generated from three distinct promoters, all containing the open reading frame (ORF). The 5' untranslated regions (UTRs) of these transcripts contain three separate regions ∼711, 409, and 146 nucleotides (nt) upstream of the translation start, the functions of which remain unknown.

Genetic interruption of target genes for investigation of virulence factors.

Recently, more emphasis has been given to understand molecular genetics and the contribution of a gene in the disease process. In fact, increased understanding of bacterial pathogenesis and intracellular communication has revealed many potential strategies for development of novel agents to treat bacterial infection. Therefore, to study the function and the involvement of a particular gene in pathogenesis, the inactivation or interruption is very important.

Phenotypic characterization of sarR mutant in Staphylococcus aureus.

Multiple factors of Staphylococcus aureus are involved in infection. Expression of these factors is controlled by multiple regulatory systems such as, the Sar family of transcriptional regulators. The staphylococcal specific Sar family of proteins are involved in expression of numerous target genes involving virulence, autolysis, biofilm formation, antibiotic resistance, oxidative stresses, and metabolic processes.

Size-dependent bacterial growth inhibition and mechanism of antibacterial activity of zinc oxide nanoparticles.

The antibacterial properties of zinc oxide nanoparticles were investigated using both gram-positive and gram-negative microorganisms. These studies demonstrate that ZnO nanoparticles have a wide range of antibacterial activities toward various microorganisms that are commonly found in environmental settings. The antibacterial activity of the ZnO nanoparticles was inversely proportional to the size of the nanoparticles in S.

Control of thioredoxin reductase gene (trxB) transcription by SarA in Staphylococcus aureus.

Thioredoxin reductase (encoded by trxB) protects Staphylococcus aureus against oxygen or disulfide stress and is indispensable for growth. Among the different sarA family mutants analyzed, transcription of trxB was markedly elevated in the sarA mutant under conditions of aerobic as well as microaerophilic growth, indicating that SarA acts as a negative regulator of trxB expression. Gel shift analysis showed that purified SarA protein binds directly to the trxB promoter region DNA in vitro.

Transcriptional variation of regulatory and virulence genes due to different media in Staphylococcus aureus.

The pathogenesis of staphylococcal infections is a multifactorial process that depends on expression of different virulence factors. Expression of these factors is controlled by multiple regulatory systems in conjunction with environmental signals. Most of the genetic studies in Staphylococcus aureus have been performed using different growth media, therefore, we examined the effects of different growth media on transcription of the selective target (e.

Expression of the sarA family of genes in different strains of Staphylococcus aureus.

Expression of genes involved in the pathogenesis of Staphylococcus aureus is controlled by global regulatory loci, including two-component regulatory systems and transcriptional regulators. The staphylococcal-specific SarA family of transcription regulators control large numbers of target genes involved in virulence, autolysis, biofilm formation, stress responses and metabolic processes, and are recognized as potential therapeutic targets. Expression of some of these important regulators has been examined, mostly in laboratory strains, while the pattern of expression of these genes in other strains, especially clinical isolates, is largely unknown.

Regulation of superoxide dismutase (sod) genes by SarA in Staphylococcus aureus.

The scavenging of reactive oxygen species (ROS) within cells is regulated by several interacting factors, including transcriptional regulators. Involvement of sarA family genes in the regulation of proteins involved in the scavenging of ROS is largely unknown. In this report, we show that under aerobic conditions, the levels of sodM and sodA transcription, in particular the sodM transcript, are markedly enhanced in the sarA mutant among the tested sarA family mutants.

sarZ, a sarA family gene, is transcriptionally activated by MgrA and is involved in the regulation of genes encoding exoproteins in Staphylococcus aureus.

The expression of genes involved in the pathogenesis of Staphylococcus aureus is controlled by global regulatory loci, including two-component regulatory systems and transcriptional regulators (e.g., sar family genes).

SarA of Staphylococcus aureus binds to the sarA promoter to regulate gene expression.

The 375-bp sarA open reading frame is driven by three promoters, P1, P3, and P2. Using gel shift and DNase I footprinting assays, we found that SarA binds to two 26-bp sequences and one 31-bp sequence within the P1 and P3 promoters, respectively. Together with the results of transcription analyses, our data indicate that SarA binds to its own promoter to down-regulate sarA expression.

Antibacterial activity of ZnO nanoparticle suspensions on a broad spectrum of microorganisms.

Nanoparticle metal oxides represent a new class of important materials that are increasingly being developed for use in research and health-related applications. Highly ionic metal oxides are interesting not only for their wide variety of physical and chemical properties but also for their antibacterial activity. Although the in vitro antibacterial activity and efficacy of regular zinc oxides have been investigated, little is known about the antibacterial activity of nanoparticles of ZnO.

Regulation and characterization of rot transcription in Staphylococcus aureus.

The pathogenesis of Staphylococcus aureus infections is dependent upon expression of various virulence factors, which are under the control of multiple regulatory systems, including two-component regulatory systems and transcriptional regulators such as the SarA family of proteins. As a part of a continuing effort to understand the regulatory mechanisms that involve the SarA protein family, the regulation and physical characterization of rot transcription is described here. The rot gene, a member of the sarA family of genes, was previously characterized and has been shown to regulate a large number of genes.