Group a remains viable inside fibrin clots and gains access to human plasminogen for subsequent fibrinolysis and dissemination.

Unlabelled: Group A (GAS) is a major human pathogen that causes several invasive diseases including necrotizing fasciitis. The host coagulation cascade initiates fibrin clots to sequester bacteria to prevent dissemination into deeper tissues. GAS, especially skin-tropic bacterial strains, utilize specific virulence factors, plasminogen binding M-protein (PAM) and streptokinase (SK), to manipulate hemostasis and activate plasminogen to cause fibrinolysis and fibrin clot escape.

High-resolution cryo-EM analysis of a Streptococcus pyogenes M-protein/human plasminogen complex.

The importance of human plasminogen (hPg)/plasmin (hPm)/cell receptor complexes in invasiveness of cells has been amply established. The objective of this investigation was to determine a high-resolution structure of a major Group A Streptococcus (GAS) bacterial receptor (PAM) for hPg/hPm when bound on a cell surface to its major ligand, hPg. As a model cell surface with endogenous PAM, we employed engineered PAM-expressing lentivirus (LV) particles.

Plasminogen missense variants and their involvement in cardiovascular and inflammatory disease.

Human plasminogen (PLG), the zymogen of the fibrinolytic protease, plasmin, is a polymorphic protein with two widely distributed codominant alleles, PLG/Asp and PLG/Asn. About 15 other missense or non-synonymous single nucleotide polymorphisms (nsSNPs) of PLG show major, yet different, relative abundances in world populations. Although the existence of these relatively abundant allelic variants is generally acknowledged, they are often overlooked or assumed to be non-pathogenic.

Fibrinolytic-deficiencies predispose hosts to septicemia from a catheter-associated UTI.

Catheter-associated urinary tract infections (CAUTIs) are amongst the most common nosocomial infections worldwide and are difficult to treat partly due to development of multidrug-resistance from CAUTI-related pathogens. Importantly, CAUTI often leads to secondary bloodstream infections and death. A major challenge is to predict when patients will develop CAUTIs and which populations are at-risk for bloodstream infections.

Blunted blades: new CRISPR-derived technologies to dissect microbial multi-drug resistance and biofilm formation.

The spread of multi-drug-resistant (MDR) pathogens has rapidly outpaced the development of effective treatments. Diverse resistance mechanisms further limit the effectiveness of our best treatments, including multi-drug regimens and last line-of-defense antimicrobials. Biofilm formation is a powerful component of microbial pathogenesis, providing a scaffold for efficient colonization and shielding against anti-microbials, which further complicates drug resistance studies.

Antimicrobial peptide-conjugated phage-mimicking nanoparticles exhibit potent bactericidal action against in murine wound infection models.

is a causative agent for strep throat, impetigo, and more invasive diseases. The main reason for the treatment failure of streptococcal infections is increased antibiotic resistance. In recent years, infectious diseases caused by pyogenic streptococci resistant to multiple antibiotics have been rising with a significant impact on public health and the veterinary industry.

Fibrinolytic-deficiencies predispose hosts to septicemia from a catheter-associated UTI.

Catheter-associated urinary tract infections (CAUTIs) are amongst the most common nosocomial infections worldwide and are difficult to treat due to multi-drug resistance development among the CAUTI-related pathogens. Importantly, CAUTI often leads to secondary bloodstream infections and death. A major challenge is to predict when patients will develop CAUTIs and which populations are at-risk for bloodstream infections.

Altered Smooth Muscle Cell Histone Acetylome by the SPHK2/S1P Axis Promotes Pulmonary Hypertension.

Background: Epigenetic regulation of vascular remodeling in pulmonary hypertension (PH) is poorly understood. Transcription regulating, histone acetylation code alters chromatin accessibility to promote transcriptional activation. Our goal was to identify upstream mechanisms that disrupt epigenetic equilibrium in PH.

Inactivation of the lysine binding sites of human plasminogen (hPg) reveals novel structural requirements for the tight hPg conformation, M-protein binding, and rapid activation.

Accelerated activation of the human plasminogen zymogen (hPg) to two-chain active plasmin (hPm) is achieved following conformational changes induced by ligand-binding at the lysine-binding sites (LBSs) in four of the five hPg kringle domains. In this manner, pattern D skin-trophic strains of Group A streptococci (GAS), through the expression of surface plasminogen-binding M-protein (PAM), immobilize surface hPg, thereby enabling rapid hPg activation by GAS-secreted streptokinase (SK). Consequently, GAS enhances virulence by digesting extracellular and tight cellular junctional barriers using hPm activity.

Generation and characterization of a plasminogen-binding group A streptococcal M-protein/streptokinase-sensitive mouse line.

Background: Streptococcus pyogenes (GAS) is a human bacterial pathogen that generates various mild to severe diseases. Worldwide, there are approximately 700 million cases of GAS infections per year. In some strains of GAS, the surface-resident M-protein, plasminogen-binding group A streptococcal M-protein (PAM), binds directly to human host plasminogen (hPg), where it is activated to plasmin through a mechanism involving a Pg/bacterial streptokinase (SK) complex as well as endogenous activators.

Analysis and Characterization of Glutathione Peroxidases in an Environmental Microbiome and Isolated Bacterial Microorganisms.

Glutathione peroxidases (Gpx) are a group of antioxidant enzymes that protect cells or tissues against damage from reactive oxygen species (ROS). The Gpx proteins identified in mammals exhibit high catalytic activity toward glutathione (GSH). In contrast, a variety of non-mammalian Gpx proteins from diverse organisms, including fungi, plants, insects, and rodent parasites, show specificity for thioredoxin (TRX) rather than GSH and are designated as TRX-dependent peroxiredoxins.

High-Resolution Single-Particle Cryo-EM Hydrated Structure of Enolase Offers Insights into Its Function as a Plasminogen Receptor.

Cellular plasminogen (Pg) receptors (PgRs) are utilized to recruit Pg; stimulate its activation to the serine protease, plasmin (Pm); and sterically protect the surface Pm from inactivation by host inhibitors. One such PgR is the moonlighting enzyme, enolase, some of which leaves the cytoplasm and resides at the cell surface to potentially function as a PgR. Since microbes employ conscription of host Pg by PgRs as one virulence mechanism, we explored the structural basis of the ability of enolase (Sen) to function in this manner.

Spike protein receptor-binding domains from SARS-CoV-2 variants of interest bind human ACE2 more tightly than the prototype spike protein.

Several SARS-CoV-2 variants of interest (VOI) have emerged since this virus was first identified as the etiologic agent responsible for COVID-19. Some of these variants have demonstrated differences in both virulence and transmissibility, as well as in evasion of immune responses in hosts vaccinated against the original strain of SARS-CoV-2. There remains a lack of definitive evidence that identifies the genetic elements that are responsible for the differences in transmissibility among these variants.

Streptolysin S targets the sodium-bicarbonate cotransporter NBCn1 to induce inflammation and cytotoxicity in human keratinocytes during Group A Streptococcal infection.

Group A (GAS, ) is a Gram-positive human pathogen that employs several secreted and surface-bound virulence factors to manipulate its environment, allowing it to cause a variety of disease outcomes. One such virulence factor is Streptolysin S (SLS), a ribosomally-produced peptide toxin that undergoes extensive post-translational modifications. The activity of SLS has been studied for over 100 years owing to its rapid and potent ability to lyse red blood cells, and the toxin has been shown to play a major role in GAS virulence .

COVID-19 Induces Cytokine Storm and Dysfunctional Hemostasis.

Background: Infection with SARS-CoV-2 leads to COVID-19 which can manifest in various ways from asymptomatic or mild disease to acute respiratory distress syndrome. The occurrence of dysregulated inflammatory responses in the form of a cytokine storm has been reported in patients with severe COVID-19. Infection can also lead to dysfunctional hemostasis reflected in elevated circulating D-dimer and fibrin degradation products.

Cell Entry and Unusual Replication of SARS-CoV-2.

Background: SARS-CoV-2 is the causative virus for the CoVID-19 pandemic that has frequently mutated to continue to infect and resist available vaccines. Emerging new variants of the virus have complicated notions of immunity conferred by vaccines versus immunity that results from infection. While we continue to progress from epidemic to endemic as a result of this collective immunity, the pandemic remains a morbid and mortal problem.

The Role of Host-Cellular Responses in COVID-19 Endothelial Dysfunction.

SARS-CoV2, Severe acute respiratory syndrome coronavirus 2, is a novel member of the human coronavirus family that has recently emerged worldwide to cause COVID-19 disease. COVID-19 disease has been declared a worldwide pandemic with over 270 million total cases, and >5 million deaths as of this writing. Although co-morbidities and preexisting conditions have played a significant role in the severity of COVID-19, the hallmark feature of severe disease associated with SARS-CoV2 is respiratory failure.

Relationships Between Plasminogen-Binding M-Protein and Surface Enolase for Human Plasminogen Acquisition and Activation in .

The proteolytic activity of human plasmin (hPm) is utilized by various cells to provide a surface protease that increases the potential of cells to migrate and disseminate. Skin-trophic Pattern D strains of (GAS), e.g.

Evolution of Streptococcus pyogenes has maximized the efficiency of the Sortase A cleavage motif for cell wall transpeptidation.

Trafficking of M-protein (Mprt) from the cytosol of Group A Streptococcus pyogenes (GAS) occurs via Sec translocase membrane channels that associate with Sortase A (SrtA), an enzyme that catalyzes cleavage of Mprt at the proximal C-terminal [-LPSTGEAA-] motif and subsequent transpeptidation of the Mprt-containing product to the cell wall (CW). These steps facilitate stable exposure of the N-terminus of Mprt to the extracellular milieu where it interacts with ligands. Previously, we found that inactivation of SrtA in GAS cells eliminated Mprt CW transpeptidation but effected little reduction in its cell surface exposure, indicating that the C-terminus of Mprt retained in the cytoplasmic membrane (CM) extends its N-terminus to the cell surface.

Binding of the kringle-2 domain of human plasminogen to streptococcal PAM-type M-protein causes dissociation of PAM dimers.

The direct binding of human plasminogen (hPg), via its kringle-2 domain (K2 ), to streptococcal M-protein (PAM), largely contributes to the pathogenesis of Pattern D Group A Streptococcus pyogenes (GAS). However, the mechanism of complex formation is unknown. In a system consisting of a Class II PAM from Pattern D GAS isolate NS88.

The Role of Bacterial Proteases in Microbe and Host-microbe Interactions.

Background: Secreted proteases are an important class of factors used by bacterial to modulate their extracellular environment through the cleavage of peptides and proteins. These proteases can range from broad, general proteolytic activity to high degrees of substrate specificity. They are often involved in interactions between bacteria and other species, even across kingdoms, allowing bacteria to survive and compete within their niche.

Group A Induced Activation of Human Plasminogen Is Required for Keratinocyte Wound Retraction and Rapid Clot Dissolution.

Invasive outcomes of Group A (GAS) infections that involve damage to skin and other tissues are initiated when these bacteria colonize and disseminate an open wound to gain access to blood and deeper tissues. Two critical GAS virulence factors, Plasminogen-Associated M-Protein (PAM) and streptokinase (SK), work in concert to bind and activate host human plasminogen (hPg) in order to create a localized proteolytic environment that alters wound-site architecture. Using a wound scratch assay with immortalized epithelial cells, real-time live imaging (RTLI) was used to examine dynamic effects of hPg activation by a PAM-containing skin-trophic GAS isolate (AP53RS) during the course of infection.

Demonstration of Three Distinct High-Molecular-Weight Complexes between Plasminogen Activator Inhibitor Type 1 and Tissue-Type Plasminogen Activator.

Background: Details of the molecular interaction between tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor type-1 (PAI-1) remain unknown.

Methods And Results: Three distinct forms of high-molecular-weight complexes are demonstrated. Two of the forms were detected by mass spectrometry.