The iron-regulated surface determinant protein B (IsdB) has recently been shown to bind to toll-like receptor 4 (TLR4), thereby inducing a strong inflammatory response in innate immune cells. Currently, two unsolved questions are (i) What is the molecular mechanism of the IsdB-TLR4 interaction? and (ii) Does it also play a role in nonimmune systems? Here, we use single-molecule experiments to demonstrate that IsdB binds TLR4 with both weak and extremely strong forces and that the mechanostability of the molecular complex is dramatically increased by physical stress, sustaining forces up to 2000 pN, at a loading rate of 10 pN/s. We also show that TLR4 binding by IsdB mediates time-dependent bacterial adhesion to endothelial cells, pointing to the role of this bond in cell invasion.
View Article and Find Full Text PDFClin Microbiol Rev
January 2025
SUMMARY is a major human pathogen. It can cause many types of infections, in particular bacteremia, which frequently leads to infective endocarditis, osteomyelitis, sepsis, and other debilitating diseases. The development of secondary infections is based on the bacterium's ability to associate with endothelial cells lining blood vessels.
View Article and Find Full Text PDFPhagocytosis is an essential mechanism of the human immune system where pathogens are eliminated by immune cells. The CCN1 protein plays an important role in the phagocytosis of by favoring the bridging of the αβ integrin to the bacterial peptidoglycan (PG), through mechanical forces that remain unknown. Here, we employ single-molecule experiments to unravel the nanomechanics of the PG-CCN1-αβ ternary complex.
View Article and Find Full Text PDFis an emerging high-virulent pathogen. Here, the presence and expression of virulence genes (, , , , , and , and genes of the putative and ) and the ability to induce synergistic hemolytic activity and hemolysis after 24, 48 and 72 h were investigated in a collection of twenty-two clinical isolates. The collection of isolates, mainly from implant orthopedic infections, had previously been grouped by ribotyping/dendrogram analysis and studied for biofilm matrices, biomasses and antibiotic resistances.
View Article and Find Full Text PDFThe secreted von Willebrand factor-binding protein (vWbp) from Staphylococcus aureus interacts with the coagulation factors prothrombin and fibrinogen (Fbg), leading to the non-proteolytic transglutaminase activation of Factor XIII (FXIII). In this study we found that vWbp-activated FXIII catalyses the incorporation of amino-donor dansylcadaverine into region A of fibronectin-binding protein A (FnBPA). Incubation of Fbg with recombinant region A of S.
View Article and Find Full Text PDFVarious viruses and pathogenic bacteria interact with annexin A2 to invade mammalian cells. Here, we show that engages in extremely strong catch bonds for host cell invasion. By means of single-molecule atomic force microscopy, we find that bacterial surface-located clumping factors bind annexin A2 with extraordinary strength, indicating that these bonds are extremely resilient to mechanical tension.
View Article and Find Full Text PDFThe use of indwelling medical devices has constantly increased in recent years and has revolutionized the quality of life of patients affected by different diseases. However, despite the improvement of hygiene conditions in hospitals, implant-associated infections remain a common and serious complication in prosthetic surgery, mainly in the orthopedic field, where infection often leads to implant failure. is the most common cause of biomaterial-centered infection.
View Article and Find Full Text PDFThe binding of Streptococcus pneumoniae to collagen is likely an important step in the pathogenesis of pneumococcal infections, but little is known of the underlying molecular mechanisms. Streptococcal surface repeats (SSURE) are highly conserved protein domains present in cell wall adhesins from different Streptococcus species. We find here that SSURE repeats of the pneumococcal adhesin plasminogen and fibronectin binding protein B (PfbB) bind to various types of collagen.
View Article and Find Full Text PDFStaphylococcus aureus is the cause of a spectrum of diseases in humans and animals. The molecular basis of this pathogenicity lies in the expression of a variety of virulence factors, including proteins that mediate adherence to the host plasma and extracellular matrix proteins. In this study, we discovered that the iron-regulated surface determinant B (IsdB) protein, besides being involved in iron transport and vitronectin binding, interacts with von Willebrand Factor (vWF).
View Article and Find Full Text PDFStaphylococci bind to the blood protein von Willebrand Factor (vWF), thereby causing endovascular infections. Whether and how this interaction occurs with the medically important pathogen is unknown. Using single-molecule experiments, we demonstrate that the protein Aap binds vWF an ultrastrong force, ∼3 nN, the strongest noncovalent biological bond ever reported, and we show that this interaction is activated by tensile loading, suggesting a catch-bond behavior.
View Article and Find Full Text PDFComput Struct Biotechnol J
June 2021
Neutrophil extracellular traps (NETs) are considered part of the innate human immune system because they are involved in host defense during bacterial infections. NETs are formed by activated neutrophils and consist of a DNA backbone combined with proteins with different biological functions. The activity of NETs can be significantly reduced by a DNase, which degrades the DNA backbone and enables the liberation of bacteria from NETs, and by Eap, a secreted protein which binds and aggregates linearized DNA, suppressing the formation of NETs.
View Article and Find Full Text PDFStaphylococci (specifically and ) are the causative agents of diseases ranging from superficial skin and soft tissue infections to severe conditions such as fatal pneumonia, bacteremia, sepsis and endocarditis. The widespread and indiscriminate use of antibiotics has led to serious problems of resistance to staphylococcal disease and has generated a renewed interest in alternative therapeutic agents such as vaccines and antibodies. Staphylococci express a large repertoire of surface and secreted virulence factors, which provide mechanisms (adhesion, invasion and biofilm development among others) for both bacterial survival in the host and evasion from innate and adaptive immunity.
View Article and Find Full Text PDFThe Staphylococcus aureus cell wall-anchored adhesin ClfA binds to the very large blood circulating protein, von Willebrand factor (vWF) via vWF-binding protein (vWbp), a secreted protein that does not bind the cell wall covalently. Here we perform force spectroscopy studies on living bacteria to unravel the molecular mechanism of this interaction. We discover that the presence of all three binding partners leads to very high binding forces (2000 pN), largely outperforming other known ternary complexes involving adhesins.
View Article and Find Full Text PDFBinding of surface proteins to endothelial cell integrins plays essential roles in host cell adhesion and invasion, eventually leading to life-threatening diseases. The staphylococcal protein IsdB binds to β3-containing integrins through a mechanism that has never been thoroughly investigated. Here, we identify and characterize at the nanoscale a previously undescribed stress-dependent adhesion between IsdB and integrin αβ.
View Article and Find Full Text PDFSingle-molecule experiments have recently revealed that the interaction between staphylococcal surface proteins and their ligands can be extremely strong, equivalent to the strength of covalent bonds. Here, we report on the unusually high binding strength between iron-regulated surface determinant B (IsdB) and vitronectin (Vn), an essential human blood protein known to interact with bacterial pathogens. The IsdB-Vn interaction is dramatically strengthened by mechanical tension, with forces up to 2000 pN at a loading rate of 10 pN s.
View Article and Find Full Text PDFPhysical forces have profound effects on cellular behavior, physiology, and disease. Perhaps the most intruiguing and fascinating example is the formation of catch-bonds that strengthen cellular adhesion under shear stresses. Today mannose-binding by the Escherichia coli FimH adhesin remains one of the rare microbial catch-bond thoroughly characterized at the molecular level.
View Article and Find Full Text PDF, one of the most important human pathogens, is the causative agent of several infectious diseases including sepsis, pneumonia, osteomyelitis, endocarditis and soft tissue infections. This pathogenicity is due to a multitude of virulence factors including several cell wall-anchored proteins (CWA). CWA proteins have modular structures with distinct domains binding different ligands.
View Article and Find Full Text PDFThe bacterial pathogen is involved in canine otitis externa and pyoderma as well as in surgical wound and urinary tract infections. Invasion of canine epithelial cells is promoted by fibronectin (Fn)-binding proteins SpsD and SpsL through molecular interactions that are currently unknown. By means of single-molecule experiments, we discover that both adhesins have distinct molecular mechanisms for binding to Fn.
View Article and Find Full Text PDFStaphylococcus pseudintermedius surface protein SpsD binds to extracellular matrix proteins to invade canine epithelial cells. Using single-molecule experiments, we show that SpsD engages in two modes of interaction with elastin that are tightly controlled by physical stress. Binding is weak (∼100 pN) at low tensile force (i.
View Article and Find Full Text PDFis an important bacterial pathogen that can cause a wide spectrum of diseases in humans and other animals. expresses a variety of virulence factors that promote infection with this pathogen. These include cell-surface proteins that mediate adherence of the bacterial cells to host extracellular matrix components, such as fibronectin and fibrinogen.
View Article and Find Full Text PDFis an emerging high-virulent pathogen causative of hospital-acquired infections. Biofilm formation is a complex pathogenic process that leads to well-established bacterial communities. There is a paucity of data on the composition of the biofilm matrix among strains.
View Article and Find Full Text PDFFibronectin is a multidomain glycoprotein ubiquitously detected in extracellular fluids and matrices of a variety of animal and human tissues where it functions as a key link between matrices and cells. Fibronectin has also emerged as the target for a large number of microorganisms, particularly bacteria. There are clear indications that the binding of microorganism' receptors to fibronectin promotes attachment to and infection of host cells.
View Article and Find Full Text PDFBinding of the surface protein clumping factor A (ClfA) to endothelial cell integrin αβ plays a crucial role during sepsis, by causing endothelial cell apoptosis and loss of barrier integrity. ClfA uses the blood plasma protein fibrinogen (Fg) to bind to αβ but how this is achieved at the molecular level is not known. Here we investigate the mechanical strength of the three-component ClfA-Fg-αβ interaction on living bacteria, by means of single-molecule experiments.
View Article and Find Full Text PDFAttachment of to platelets and endothelial cells involves binding of bacterial cell surface protein A (SpA) to the large plasma glycoprotein von Willebrand factor (vWF). SpA-mediated bacterial adhesion to vWF is controlled by fluid shear stress, yet little is currently known about the underlying molecular mechanism. In a recent publication, we showed that the SpA-vWF interaction is tightly regulated by mechanical force.
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