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.

Coagulation factor XII contributes to renin activation, heart failure progression, and mortality.

Symptomatic heart failure (sHF) with cardiac dysfunction, edema, and mortality are driven by overactivation of the renin-angiotensin-aldosterone system (RAAS). Renin is widely recognized as a key initiator of RAAS function, yet the mechanisms that activate renin remain a mystery. We discovered that activated coagulation factor XII generates active renin in the circulation and is directly linked to pathological activation of the systemic RAAS, development of sHF, and increased mortality.

The catheterized bladder environment induces dysregulation of macrophage polarization exacerbating bacterial UTI.

Urinary catheterization causes bladder damage, predisposing hosts to catheter-associated urinary tract infections (CAUTIs). CAUTI pathogenesis is mediated by bladder damage-induced inflammation, resulting in accumulation and deposition of the blood-clotting protein fibrinogen (Fg) and its matrix form fibrin, which are exploited by uropathogens as biofilm platforms to establish infection. Catheter-induced inflammation also results in robust immune cell recruitment, including macrophages (Mϕs).

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.

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 .

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.

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.

Fibrin is a critical regulator of neutrophil effector function at the oral mucosal barrier.

Tissue-specific cues are critical for homeostasis at mucosal barriers. Here, we report that the clotting factor fibrin is a critical regulator of neutrophil function at the oral mucosal barrier. We demonstrate that commensal microbiota trigger extravascular fibrin deposition in the oral mucosa.

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.

Streptococcus co-opts a conformational lock in human plasminogen to facilitate streptokinase cleavage and bacterial virulence.

Virulent strains of Streptococcus pyogenes (gram-positive group A Streptococcus pyogenes [GAS]) recruit host single-chain human plasminogen (hPg) to the cell surface-where in the case of Pattern D strains of GAS, hPg binds directly to the cells through a surface receptor, plasminogen-binding group A streptococcal M-protein (PAM). The coinherited Pattern D GAS-secreted streptokinase (SK2b) then accelerates cleavage of hPg at the R-V peptide bond, resulting in the disulfide-linked two-chain protease, human plasmin (hPm). hPm localizes on the bacterial surface, assisting bacterial dissemination via proteolysis of host defense proteins.

Stable genetic integration of a red fluorescent protein in a virulent Group A strain.

There are several advantages, both and , in utilizing bacteria that express a fluorescent protein. Such a protein can be transiently incorporated into the bacteria or integrated within the bacterial genome. The most widely utilized fluorescent protein is green fluorescent protein (GFP), but limitations exist on its use.