Identification of an antivirulence agent targeting the master regulator of virulence genes in .

The emergence of bactericidal antibiotic-resistant strains has increased the demand for alternative therapeutic agents, such as antivirulence agents targeting the virulence regulators of pathogens. exoprotein expression () locus, the master regulator of virulence gene expression in multiple drug-resistant , is a promising therapeutic target. In this study, we screened a small-molecule library using a SaeRS green fluorescent protein (GFP)-reporter that responded to transcription controlled by the locus.

Regulation of Bacterial Two-Component Systems by Cardiolipin.

The regulation of membrane protein activity for cellular functions is critically dependent on the composition of phospholipid membranes. Cardiolipin, a unique phospholipid found in bacterial membranes and mitochondrial membranes of eukaryotes, plays a crucial role in stabilizing membrane proteins and maintaining their function. In the human pathogen Staphylococcus aureus, the SaeRS two-component system (TCS) controls the expression of key virulence factors essential for the bacterium's virulence.

Modulation of MRSA virulence gene expression by the wall teichoic acid enzyme TarO.

Phenol-soluble modulins (PSMs) and Staphylococcal protein A (SpA) are key virulence determinants for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), an important human pathogen that causes a wide range of diseases. Here, using chemical and genetic approaches, we show that inhibition of TarO, the first enzyme in the wall teichoic acid (WTA) biosynthetic pathway, decreases the expression of genes encoding PSMs and SpA in the prototypical CA-MRSA strain USA300 LAC. Mechanistically, these effects are linked to the activation of VraRS two-component system that directly represses the expression of accessory gene regulator (agr) locus and spa.

Regulation of Bacterial Two-Component Systems by Cardiolipin.

The composition of phospholipid membranes is critical to regulating the activity of membrane proteins for cellular functions. Cardiolipin is a unique phospholipid present within the bacterial membrane and mitochondria of eukaryotes and plays a role in maintaining the function and stabilization of membrane proteins. Here, we report that, in the human pathogen Staphylococcus aureus, cardiolipin is required for full activity of the SaeRS two-component system (TCS).

A novel copper-sensing two-component system for inducing Dsb gene expression in bacteria.

In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here, we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa; in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation (Dsb) (i.e.

Regulation of the Sae Two-Component System by Branched-Chain Fatty Acids in Staphylococcus aureus.

Staphylococcus aureus is a ubiquitous Gram-positive bacterium and an opportunistic human pathogen. S. aureus pathogenesis relies on a complex network of regulatory factors that adjust gene expression.

Staphylococcus aureus Does Not Synthesize Arginine from Proline under Physiological Conditions.

The Gram-positive pathogen Staphylococcus aureus is the only bacterium known to synthesize arginine from proline via the arginine-proline interconversion pathway despite having genes for the well-conserved glutamate pathway. Since the proline-arginine interconversion pathway is repressed by CcpA-mediated carbon catabolite repression (CCR), CCR has been attributed to the arginine auxotrophy of S. aureus.

Unravelling the physiological roles of mazEF toxin-antitoxin system on clinical MRSA strain by CRISPR RNA-guided cytidine deaminase.

Background: Curiosity on toxin-antitoxin modules has increased intensely over recent years as it is ubiquitously present in many bacterial genomes, including pathogens like Methicillin-resistant Staphylococcus aureus (MRSA). Several cellular functions of TA systems have been proposed however, their exact role in cellular physiology remains unresolved.

Methods: This study aims to find out the impact of the mazEF toxin-antitoxin module on biofilm formation, pathogenesis, and antibiotic resistance in an isolated clinical ST239 MRSA strain, by constructing mazE and mazF mutants using CRISPR-cas9 base-editing plasmid (pnCasSA-BEC).

Virulence adaption to environment promotes the age-dependent nasal colonization of .

is an important human commensal bacteria colonizing the human body, especially the nasal cavity. The nasal carriage can be a source of bacteremia. However, the bacterial factors contributing to nasal colonization are not completely understood.

Molybdopterin biosynthesis pathway contributes to the regulation of SaeRS two-component system by ClpP in .

In , the SaeRS two-component system is essential for the bacterium's hemolytic activity and virulence. The Newman strain of contains a variant of SaeS sensor kinase, SaeS L18P. Previously, we showed that, in the strain Newman, SaeS L18P is degraded by the membrane-bound protease FtsH.

Comparative Genomic Analysis of a Panton-Valentine Leukocidin-Positive ST22 Community-Acquired Methicillin-Resistant from Pakistan.

() ST22 is considered a clinically important clone because an epidemic strain EMRSA-15 belongs to ST22, and several outbreaks of this clone have been documented worldwide. We performed genomic analysis of an strain Lr2 ST22 from Pakistan and determined comparative analysis with other ST22 strains. The genomic data show that Lr2 belongs to -type t2986 and harbors staphylococcal cassette chromosome (SCC) type IVa(2B), one complete plasmid, and seven prophages or prophage-like elements.

In silico designed Staphylococcus aureus B-cell multi-epitope vaccine did not elicit antibodies against target antigens suggesting multi-domain approach.

The vaccine development strategies have evolved from using an entire organism as an immunogen to a single antigen and further towards an epitope. Since an epitope is a relatively tiny and immunologically relevant part of an antigen, it has the potential to stimulate more robust and specific immune responses while causing minimal adverse effects. As a result, the recent focus of vaccine development has been to develop multi-epitope vaccines that can target multiple virulence mechanisms.

Ftsh Sensitizes Methicillin-Resistant to β-Lactam Antibiotics by Degrading YpfP, a Lipoteichoic Acid Synthesis Enzyme.

In the Gram-positive pathogen , FtsH, a membrane-bound metalloprotease, plays a critical role in bacterial virulence and stress resistance. This protease is also known to sensitize methicillin-resistant (MRSA) to β-lactam antibiotics; however, the molecular mechanism is not known. Here, by the analysis of FtsH substrate mutants, we found that FtsH sensitizes MRSA specifically to β-lactams by degrading YpfP, the enzyme synthesizing the anchor molecule for lipoteichoic acid (LTA).

Genomic Investigation of Methicillin-Resistant ST113 Strains Isolated from Tertiary Care Hospitals in Pakistan.

Methicillin-resistant (MRSA) is a multi-drug resistant and opportunistic pathogen. The emergence of new clones of MRSA in both healthcare settings and the community warrants serious attention and epidemiological surveillance. However, epidemiological data of MRSA isolates from Pakistan are limited.

Development of Combination Vaccine Conferring Optimal Protection against Six Pore-Forming Toxins of Staphylococcus aureus.

In the Gram-positive pathogen Staphylococcus aureus, pore-forming toxins (PFTs), such as leukocidins and hemolysins, play prominent roles in staphylococcal pathogenesis by killing host immune cells and red blood cells (RBCs). However, it remains unknown which combination of toxin antigens would induce the broadest protective immune response against those toxins. In this study, by targeting six major staphylococcal PFTs (i.

Histamine activates HinK to promote the virulence of Pseudomonas aeruginosa.

During infections, bacteria stimulate host cells to produce and release histamine, which is a key mediator of vital cellular processes in animals. However, the mechanisms underlying the bacterial cell's ability to sense and respond to histamine are poorly understood. Herein, we show that HinK, a LysR-type transcriptional regulator, is required to evoke responses to histamine in Pseudomonas aeruginosa, an important human pathogen.

The N2N3 domains of ClfA, FnbpA and FnbpB in Staphylococcus aureus bind to human complement factor H, and their antibodies enhance the bactericidal capability of human blood.

In the complement system, the opsonin C3b binds to the bacterial cell surface and mediates the opsonophagocytosis. However, the cell-wall protein SdrE of Staphylococcus aureus inhibits the C3b activity by recruiting the complement regulatory protein factor H (fH). SdrE binds to fH via its N-terminal N2N3 domain, which are also found in six other staphylococcal cell-wall proteins.

Mutation-induced remodeling of the BfmRS two-component system in clinical isolates.

Genetic mutations are a primary driving force behind the adaptive evolution of bacterial pathogens. Multiple clinical isolates of , an important human pathogen, have naturally evolved one or more missense mutations in , which encodes the sensor histidine kinase of the BfmRS two-component system (TCS). A mutant BfmS protein containing both the L181P and E376Q substitutions increased the phosphorylation and thus the transcriptional regulatory activity of its cognate downstream response regulator, BfmR.

Author Correction: Rewiring of the FtsH regulatory network by a single nucleotide change in saeS of Staphylococcus aureus.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Roles of the Site 2 Protease Eep in Staphylococcus aureus.

In , the site 2 protease Eep generates sex pheromones, including cAM373. Intriguingly, in , a peptide similar to cAM373, named cAM373_SA, is produced from the 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.

Alteration of protein homeostasis mediates the interaction of Pseudomonas aeruginosa with Staphylococcus aureus.

Intracellular protein degradation is essential for the survival of all organisms, but its role in interspecies interaction is unknown. Here, we show that the ClpXP protease of Pseudomonas aeruginosa suppresses its antimicrobial activity against Staphylococcus aureus, a common pathogen co-isolated with P. aeruginosa from polymicrobial human infections.

A Membrane-Bound Transcription Factor is Proteolytically Regulated by the AAA+ Protease FtsH in Staphylococcus aureus.

In bacteria, chromosomal DNA resides in the cytoplasm, and most transcription factors are also found in the cytoplasm. However, some transcription factors, called membrane-bound transcription factors (MTFs), reside in the cytoplasmic membrane. Here, we report the identification of a new MTF in the Gram-positive pathogen and its regulation by the protease FtsH.

In Staphylococcus aureus, the Particulate State of the Cell Envelope Is Required for the Efficient Induction of Host Defense Responses.

Upon microbial infection, host immune cells recognize bacterial cell envelope components through cognate receptors. Although bacterial cell envelope components function as innate immune molecules, the role of the physical state of the bacterial cell envelope (i.e.