The Experts below are selected from a list of 1446 Experts worldwide ranked by ideXlab platform
Wendy E. Thomas - One of the best experts on this subject based on the ideXlab platform.
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rmsd analysis of structures of the bacterial protein fimh identifies five conformations of its lectin domain
Proteins, 2020Co-Authors: Pearl Magala, Wendy E. Thomas, Evgeni V. Sokurenko, Rachel E Klevit, Ronald E StenkampAbstract:FimH is a bacterial adhesin protein located at the tip of Escherichia coli fimbria that functions to adhere bacteria to host cells. Thus, FimH is a critical factor in bacterial infections such as urinary tract infections and is of interest in drug development. It is also involved in vaccine development and as a model for understanding shear-enhanced Catch Bond cell adhesion. To date, over 60 structures have been deposited in the Protein Data Bank showing interactions between FimH and mannose ligands, potential inhibitors, and other fimbrial proteins. In addition to providing insights about ligand recognition and fimbrial assembly, these structures provide insights into conformational changes in the two domains of FimH that are critical for its function. To gain further insights into these structural changes, we have superposed FimH's mannose binding lectin domain in all these structures and categorized the structures into five groups of lectin domain conformers using RMSD as a metric. Many structures also include the pilin domain, which anchors FimH to the fimbriae and regulates the conformation and function of the lectin domain. For these structures, we have also compared the relative orientations of the two domains. These structural analyses enhance our understanding of the conformational changes associated with FimH ligand binding and domain-domain interactions, including its Catch Bond behavior through allosteric action of force in bacterial adhesion.
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The bacterial fimbrial tip acts as a mechanical force sensor. PLoS Biol
2016Co-Authors: Pavel Aprikian, Veronika Tchesnokova, Ronald E Stenkamp, Brian A Kidd, Gianluca Interl, Isolde Le Trong, Matt J. Whitfield, Esther Bullitt, Wendy E. ThomasAbstract:There is increasing evidence that the Catch Bond mechanism, where binding becomes stronger under tensile force, is a common property among non-covalent interactions between biological molecules that are exposed to mechanical force in vivo. Here, by using the multi-protein tip complex of the mannose-binding type 1 fimbriae of Escherichia coli, we show how the entire quaternary structure of the adhesive organella is adapted to facilitate binding under mechanically dynamic conditions induced by flow. The fimbrial tip mediates shear-dependent adhesion of bacteria to uroepithelial cells and demonstrates force-enhanced interaction with mannose in single molecule force spectroscopy experiments. The mannose-binding, lectin domain of the apex-positioned adhesive protein FimH is docked to the anchoring pilin domain in a distinct hooked manner. The hooked conformation is highly stable in molecular dynamics simulations under no force conditions but permits an easy separation of the domains upon application of an external tensile force, allowing the lectin domain to switch from a low- to a high-affinity state. The conformation between the FimH pilin domain and the following FimG subunit of the tip is open and stable even when tensile force is applied, providing an extended lever arm for the hook unhinging under shear. Finally, the conformation between FimG and FimF subunits is highly flexible even in the absence of tensile force, conferring to the FimH adhesin an exploratory function and high binding rates. The fimbrial tip of type 1 Escherichia coli is optimized to have a dual functionality: flexible exploration and force sensing. Comparison to othe
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The Role of Ligand Density in the Binding of Von Willebrand Factor by the Glycoprotein Ib-IX-V Complex in Platelets
Biophysical Journal, 2015Co-Authors: Zeinab Al-rekabi, Wendy E. Thomas, Joachim P. Spatz, Shirin Feghhi, Nikita Taparia, Adam D. Munday, José A. López, Nathan J. SniadeckiAbstract:The initial arrest of platelets at a wound site requires the binding of glycoprotein Ib-IX-V complex (GPIb-IX-V) to the extracellular matrix protein von Willebrand factor (VWF). Increasing forces on these Bonds increases the Bond lifetime, known as a Catch Bond. Recently, we have shown that platelets are able to transmit cytoskeletal forces through the GPIbα subunit of GPIb-IX-V, which binds to the A1 domain of VWF. This provides an internal force on the Bond to maintain adhesion in the absence of external forces. Integrin engagement and force transmission are known to require receptor clustering. We therefore investigate whether the clustering of GPIb-IX-V receptor is needed for the transmission of cytoskeletal forces to VWF. We first examined whether GPIb-IX-V clusters formed in spreading platelets. GPIbα-positive punctate structures were visualized by confocal microscopy and correlated with dark regions imaged using interference reflection microscopy (IRM), indicating that GPIb-IX-V forms adhesive contacts that are similar in size to integrin-related focal adhesions in platelets. To investigate the effect of ligand density on platelet spreading, we prepared molecularly-defined adhesive ligand spots, which were separated 28 or 108 nm apart by nonadhesive regions using self-assembling gold nanoparticles. These nanoparticles were coated with A1 domain of VWF. When seeded on nanoparticles with 28 nm spacing, platelets appeared well-spread and formed punctate adhesions. However, when seeded on 108 nm spacing, platelet adhesion was significantly reduced and those platelets that did adhere spread poorly. These findings demonstrate that an upper limit for ligand density exists where platelet adhesion and spreading are impeded. Investigating the effects of ligand spacing will facilitate an understanding of GPIbα clustering in platelet adhesion and spreading, thus providing insight into thrombotic diseases and congenital bleeding disorders.
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allosteric coupling in the bacterial adhesive protein fimh
Journal of Biological Chemistry, 2013Co-Authors: Victoria B Rodriguez, Evgeni V. Sokurenko, Veronika Tchesnokova, Brian A Kidd, Gianluca Interlandi, Wendy E. ThomasAbstract:Abstract The protein FimH is expressed by the majority of commensal and uropathogenic strains of Escherichia coli (E. coli) on the tips of type 1 fimbriae and mediates adhesion via a Catch-Bond to its ligand mannose. Crystal structures of FimH show an allosteric conformational change, but it remains unclear whether all of the observed structural differences are part of the allosteric mechanism. Here we use the protein structural analysis tool RosettaDesign combined with human insight to identify and synthesize 10 mutations in four regions that we predicted would stabilize one of the conformations of that region. The function of each variant was characterized by measuring binding to the ligand mannose while the allosteric state was determined using a conformation-specific monoclonal antibody. These studies demonstrated that each region investigated was indeed part of the FimH allosteric mechanism. However, the studies strongly suggested that some regions were more tightly coupled to mannose binding and others to antibody binding. In addition, we identified many FimH variants that appear locked in the low-affinity state. Knowledge of regulatory sites outside the active and effector sites, as well as the ability to make FimH variants locked in the low-affinity state, may be crucial to the future development of novel antiadhesive and antimicrobial therapies using allosteric regulation to inhibit FimH.
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single molecule constant force force clamp afm measurements confirm Catch Bonds and multiple binding states in bacterial adhesin fimh
Biophysical Journal, 2009Co-Authors: Wendy E. Thomas, Evgeni V. Sokurenko, Pavel Aprikian, Manu Foreroshelton, Viola VogelAbstract:Bacteria can adhere to mannose present on the surface of epithelial cells via the FimH-mannose Bond. Surprisingly, they have been shown to enhance their adhesion to the cells when fluid flow is increased. These conditions would normally weaken traditional ‘slip’ Bonds. Catch Bonds have been defined as non-covalent Bonds whose lifetime increases with tensile force on the Bond, instead of decreasing as expected for slip Bonds.Here we present results confirming Catch Bonds in FimH-mannose complexes at the single molecule level using the Atomic Force Microscope (AFM). This is the first AFM measurement of Catch Bond lifetimes using a constant force mode. In constant force mode (or force clamp), a feedback loop maintains the force at a predefined level, correcting for changes in conformation of the molecule. We observe multiple lifetimes and that force enhances the proportion of Bonds with a long lifetime. This is the first measurement that resolves multiple lifetimes in Catch Bonds while verifying that only a single molecule is tethered. We discuss the implications of these findings in the context of the mechanism giving rise to bacterial Catch Bonds.
Evgeni V. Sokurenko - One of the best experts on this subject based on the ideXlab platform.
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rmsd analysis of structures of the bacterial protein fimh identifies five conformations of its lectin domain
Proteins, 2020Co-Authors: Pearl Magala, Wendy E. Thomas, Evgeni V. Sokurenko, Rachel E Klevit, Ronald E StenkampAbstract:FimH is a bacterial adhesin protein located at the tip of Escherichia coli fimbria that functions to adhere bacteria to host cells. Thus, FimH is a critical factor in bacterial infections such as urinary tract infections and is of interest in drug development. It is also involved in vaccine development and as a model for understanding shear-enhanced Catch Bond cell adhesion. To date, over 60 structures have been deposited in the Protein Data Bank showing interactions between FimH and mannose ligands, potential inhibitors, and other fimbrial proteins. In addition to providing insights about ligand recognition and fimbrial assembly, these structures provide insights into conformational changes in the two domains of FimH that are critical for its function. To gain further insights into these structural changes, we have superposed FimH's mannose binding lectin domain in all these structures and categorized the structures into five groups of lectin domain conformers using RMSD as a metric. Many structures also include the pilin domain, which anchors FimH to the fimbriae and regulates the conformation and function of the lectin domain. For these structures, we have also compared the relative orientations of the two domains. These structural analyses enhance our understanding of the conformational changes associated with FimH ligand binding and domain-domain interactions, including its Catch Bond behavior through allosteric action of force in bacterial adhesion.
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Structural and Population Characterization of MrkD, the Adhesive Subunit of Type 3 Fimbriae
2016Co-Authors: Evgeni V. Sokurenko, Karen B A. KrogfeltaAbstract:Type 3 fimbriae are adhesive organelles found in enterobacterial pathogens. The fimbriae promote biofilm formation on biotic and abiotic surfaces; however, the exact identity of the receptor for the type 3 fimbriae adhesin, MrkD, remains elusive. We ana-lyzed naturally occurring structural and functional variabilities of the MrkD adhesin from Klebsiella pneumoniae and Esche-richia coli isolates of diverse origins. We identified a total of 33 allelic variants ofmrkD among 90 K. pneumoniae isolates and 10 allelic variants among 608 E. coli isolates, encoding 11 and 9 protein variants, respectively. Based on the level of accumulated silent variability between the alleles,mrkD was acquired a relatively long time ago in K. pneumoniae but recently in E. coli. How-ever, unlike K. pneumoniae,mrkD in E. coli is actively evolving under a strong positive selection by accumulation of mutations, often targeting the same positions in the protein. Several naturally occurring MrkD protein variants from E. coliwere found to be significantly less adherent when tested in a mannan-binding assay and showed reduced biofilm-forming capacity. Functional examination of the MrkD adhesin in flow chamber experiments determined that it interacts with Saccharomyces cerevisiae cells in a shear-dependent manner, i.e., the binding is Catch-Bond-like and enhanced under increasing shear conditions. Homology modeling strongly suggested that MrkD has a two-domain structure, comprising a pilin domain anchoring the adhesin to the fimbrial shaft and a lectin domain containing the binding pocket; this is similar to structures found in other Catch-Bond-forming fimbrial adhesins in enterobacteria
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allosteric coupling in the bacterial adhesive protein fimh
Journal of Biological Chemistry, 2013Co-Authors: Victoria B Rodriguez, Evgeni V. Sokurenko, Veronika Tchesnokova, Brian A Kidd, Gianluca Interlandi, Wendy E. ThomasAbstract:Abstract The protein FimH is expressed by the majority of commensal and uropathogenic strains of Escherichia coli (E. coli) on the tips of type 1 fimbriae and mediates adhesion via a Catch-Bond to its ligand mannose. Crystal structures of FimH show an allosteric conformational change, but it remains unclear whether all of the observed structural differences are part of the allosteric mechanism. Here we use the protein structural analysis tool RosettaDesign combined with human insight to identify and synthesize 10 mutations in four regions that we predicted would stabilize one of the conformations of that region. The function of each variant was characterized by measuring binding to the ligand mannose while the allosteric state was determined using a conformation-specific monoclonal antibody. These studies demonstrated that each region investigated was indeed part of the FimH allosteric mechanism. However, the studies strongly suggested that some regions were more tightly coupled to mannose binding and others to antibody binding. In addition, we identified many FimH variants that appear locked in the low-affinity state. Knowledge of regulatory sites outside the active and effector sites, as well as the ability to make FimH variants locked in the low-affinity state, may be crucial to the future development of novel antiadhesive and antimicrobial therapies using allosteric regulation to inhibit FimH.
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comparative structure function analysis of mannose specific fimh adhesins from klebsiella pneumoniae and escherichia coli
Journal of Bacteriology, 2009Co-Authors: Steen Gustav Stahlhut, Evgeni V. Sokurenko, Veronika Tchesnokova, Carsten Struve, Scott J Weissman, Sujay Chattopadhyay, Olga Yakovenko, Pavel Aprikian, Karen A KrogfeltAbstract:FimH, the adhesive subunit of type 1 fimbriae expressed by many enterobacteria, mediates mannose-sensitive binding to target host cells. At the same time, fine receptor-structural specificities of FimH from different species can be substantially different, affecting bacterial tissue tropism and, as a result, the role of the particular fimbriae in pathogenesis. In this study, we compared functional properties of the FimH proteins from Escherichia coli and Klebsiella pneumoniae, which are both 279 amino acids in length but differ by some ∼15% of residues. We show that K. pneumoniae FimH is unable to mediate adhesion in a monomannose-specific manner via terminally exposed Manα(1-2) residues in N-linked oligosaccharides, which are the structural basis of the tropism of E. coli FimH for uroepithelial cells. However, K. pneumoniae FimH can bind to the terminally exposed Manα(1-3)Manβ(1-4)GlcNAcβ1 trisaccharide, though only in a shear-dependent manner, wherein the binding is marginal at low shear force but enhanced sevenfold under increased shear. A single mutation in the K. pneumoniae FimH, S62A, converts the mode of binding from shear dependent to shear independent. This mutation has occurred naturally in the course of endemic circulation of a nosocomial uropathogenic clone and is identical to a pathogenicity-adaptive mutation found in highly virulent uropathogenic strains of E. coli, in which it also eliminates the dependence of E. coli binding on shear. The shear-dependent binding properties of the K. pneumoniae and E. coli FimH proteins are mediated via an allosteric Catch Bond mechanism. Thus, despite differences in FimH structure and fine receptor specificity, the shear-dependent nature of FimH-mediated adhesion is highly conserved between bacterial species, supporting its remarkable physiological significance.
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single molecule constant force force clamp afm measurements confirm Catch Bonds and multiple binding states in bacterial adhesin fimh
Biophysical Journal, 2009Co-Authors: Wendy E. Thomas, Evgeni V. Sokurenko, Pavel Aprikian, Manu Foreroshelton, Viola VogelAbstract:Bacteria can adhere to mannose present on the surface of epithelial cells via the FimH-mannose Bond. Surprisingly, they have been shown to enhance their adhesion to the cells when fluid flow is increased. These conditions would normally weaken traditional ‘slip’ Bonds. Catch Bonds have been defined as non-covalent Bonds whose lifetime increases with tensile force on the Bond, instead of decreasing as expected for slip Bonds.Here we present results confirming Catch Bonds in FimH-mannose complexes at the single molecule level using the Atomic Force Microscope (AFM). This is the first AFM measurement of Catch Bond lifetimes using a constant force mode. In constant force mode (or force clamp), a feedback loop maintains the force at a predefined level, correcting for changes in conformation of the molecule. We observe multiple lifetimes and that force enhances the proportion of Bonds with a long lifetime. This is the first measurement that resolves multiple lifetimes in Catch Bonds while verifying that only a single molecule is tethered. We discuss the implications of these findings in the context of the mechanism giving rise to bacterial Catch Bonds.
Viola Vogel - One of the best experts on this subject based on the ideXlab platform.
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single molecule constant force force clamp afm measurements confirm Catch Bonds and multiple binding states in bacterial adhesin fimh
Biophysical Journal, 2009Co-Authors: Wendy E. Thomas, Evgeni V. Sokurenko, Pavel Aprikian, Manu Foreroshelton, Viola VogelAbstract:Bacteria can adhere to mannose present on the surface of epithelial cells via the FimH-mannose Bond. Surprisingly, they have been shown to enhance their adhesion to the cells when fluid flow is increased. These conditions would normally weaken traditional ‘slip’ Bonds. Catch Bonds have been defined as non-covalent Bonds whose lifetime increases with tensile force on the Bond, instead of decreasing as expected for slip Bonds.Here we present results confirming Catch Bonds in FimH-mannose complexes at the single molecule level using the Atomic Force Microscope (AFM). This is the first AFM measurement of Catch Bond lifetimes using a constant force mode. In constant force mode (or force clamp), a feedback loop maintains the force at a predefined level, correcting for changes in conformation of the molecule. We observe multiple lifetimes and that force enhances the proportion of Bonds with a long lifetime. This is the first measurement that resolves multiple lifetimes in Catch Bonds while verifying that only a single molecule is tethered. We discuss the implications of these findings in the context of the mechanism giving rise to bacterial Catch Bonds.
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Catch Bond mechanism of force enhanced adhesion counterintuitive elusive but widespread
Cell Host & Microbe, 2008Co-Authors: Evgeni V. Sokurenko, Viola Vogel, Wendy E. ThomasAbstract:Summary Catch Bonds are Bonds between a ligand and its receptor that are enhanced by mechanical force pulling the ligand-receptor complex apart. To date, Catch-Bond formation has been documented for the most common Escherichia coli adhesin, FimH, and for P-/L-selectins, universally expressed by leukocytes, platelets, and blood vessel walls. One compelling explanation for Catch Bonds is that force-induced structural alterations in the receptor protein are allosterically linked to a high-affinity conformation of its ligand-binding pocket. Catch-Bond properties are likely to be widespread among adhesive proteins, thus calling for a detailed understanding of their underlying mechanisms and physiological significance.
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Biophysics of Catch Bonds
Annual Review of Biophysics, 2008Co-Authors: Wendy E. Thomas, Viola Vogel, Evgeni V. SokurenkoAbstract:Receptor-ligand Bonds strengthened by tensile mechanical force are referred to as Catch Bonds. This review examines experimental data and biophysical theory to analyze why mechanical force prolongs the lifetime of these Bonds rather than shortens the lifetime by pulling the ligand out of the binding pocket. Although many mathematical models can explain Catch Bonds, experiments using structural variants have been more helpful in determining how Catch Bonds work. The underlying mechanism has been worked out so far only for the bacterial adhesive protein FimH. This protein forms Catch Bonds because it is allosterically activated when mechanical force pulls an inhibitory domain away from the ligand-binding domain. Other Catch Bond–forming proteins, including blood cell adhesion proteins called selectins and the motor protein myosin, show evidence of allosteric regulation between two domains, but it remains unclear if this is related to their Catch Bond behavior.
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integrin like allosteric properties of the Catch Bond forming fimh adhesin of escherichia coli
Journal of Biological Chemistry, 2008Co-Authors: Veronika Tchesnokova, Wendy E. Thomas, Viola Vogel, Olga Yakovenko, Pavel Aprikian, Christopher N Larock, Brian A Kidd, Evgeni V. SokurenkoAbstract:FimH is the adhesive subunit of type 1 fimbriae of the Escherichia coli that is composed of a mannose-binding lectin domain and a fimbria-incorporating pilin domain. FimH is able to interact with mannosylated surface via a shear-enhanced Catch Bond mechanism. We show that the FimH lectin domain possesses a ligand-induced binding site (LIBS), a type of allosterically regulated epitopes characterized in integrins. Analogous to integrins, in FimH the LIBS epitope becomes exposed in the presence of the ligand (or "activating" mutations) and is located far from the ligand-binding site, close to the interdomain interface. Also, the antibody binding to the LIBS shifts adhesin from the low to high affinity state. Binding of streptavidin to the biotinylated residue within the LIBS also locks FimH in the high affinity state, suggesting that the allosteric perturbations in FimH are sustained by the interdomain wedging. In the presence of antibodies, the strength of bacterial adhesion to mannose is increased similar to the increase observed under shear force, suggesting the same allosteric mechanism, a shift in the interdomain configuration. Thus, an integrin-like allosteric link between the binding pocket and the interdomain conformation can serve as the basis for the Catch Bond property of FimH and, possibly, other adhesive proteins.
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interdomain interaction in the fimh adhesin of escherichia coli regulates the affinity to mannose
Journal of Biological Chemistry, 2007Co-Authors: Pavel Aprikian, Wendy E. Thomas, Viola Vogel, Veronika Tchesnokova, Olga Yakovenko, Brian A Kidd, Vladimir Yarovyarovoy, Elena Trinchina, Evgeni V. SokurenkoAbstract:FimH is a mannose-specific adhesin located on the tip of type 1 fimbriae of Escherichia coli that is capable of mediating shear-enhanced bacterial adhesion. FimH consists of a fimbria-associated pilin domain and a mannose-binding lectin domain, with the binding pocket positioned opposite the interdomain interface. By using the yeast two-hybrid system, purified lectin and pilin domains, and docking simulations, we show here that the FimH domains interact with one another. The affinity for mannose is greatly enhanced (up to 300-fold) in FimH variants in which the interdomain interaction is disrupted by structural mutations in either the pilin or lectin domains. Also, affinity to mannose is dramatically enhanced in isolated lectin domains or in FimH complexed with the chaperone molecule that is wedged between the domains. Furthermore, FimH with native structure mediates weak binding at low shear stress but shifts to strong binding at high shear, whereas FimH with disrupted interdomain contacts (or the isolated lectin domain) mediates strong binding to mannose-coated surfaces even under low shear. We propose that interactions between lectin and pilin domains decrease the affinity of the mannose-binding pocket via an allosteric mechanism. We further suggest that mechanical force at high shear stress separates the two domains, allowing the lectin domain to switch from a low affinity to a high affinity state. This shift provides a mechanism for FimH-mediated shear-enhanced adhesion by enabling the adhesin to form Catch Bond-like interactions that are longer lived at high tensile force.
Cheng Zhu - One of the best experts on this subject based on the ideXlab platform.
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the n terminal flanking region of the a1 domain regulates the force dependent binding of von willebrand factor to platelet glycoprotein ibα
Journal of Biological Chemistry, 2013Co-Authors: Jing Fei Dong, Miguel A Cruz, Cheng ZhuAbstract:Abstract Binding of platelet glycoprotein Ibα (GPIbα) to von Willebrand factor (VWF) initiates platelet adhesion to disrupted vascular surface under arterial blood flow. Flow exerts forces on the platelet that are transmitted to VWF-GPIbα Bonds, which regulate their dissociation. Mutations in VWF and/or GPIbα may alter the mechanical regulation of platelet adhesion to cause hemostatic defects as found in patients with von Willebrand disease (VWD). Using a biomembrane force probe, we observed biphasic force-decelerated (Catch) and force-accelerated (slip) dissociation of GPIbα from VWF. The VWF A1 domain that contains the N-terminal flanking sequence Gln1238–Glu1260 (1238-A1) formed triphasic slip-Catch-slip Bonds with GPIbα. By comparison, using a short form of A1 that deletes this sequence (1261-A1) abolished the Catch Bond, destabilizing its binding to GPIbα at high forces. Importantly, shear-dependent platelet rolling velocities on these VWF ligands in a flow chamber system mirrored the force-dependent single-Bond lifetimes. Adding the Gln1238–Glu1260 peptide, which interacted with GPIbα and 1261-A1 but not 1238-A1, to whole blood decreased platelet attachment under shear stress. Soluble Gln1238–Glu1260 reduced the lifetimes of GPIbα Bonds with VWF and 1238-A1 but rescued the Catch Bond of GPIbα with 1261-A1. A type 2B VWD 1238-A1 mutation eliminated the Catch Bond by prolonging lifetimes at low forces, a type 2M VWD 1238-A1 mutation shifted the respective slip-Catch and Catch-slip transition points to higher forces, whereas a platelet type VWD GPIbα mutation enhanced the Bond lifetime in the entire force regime. These data reveal the structural determinants of VWF activation by hemodynamic force of the circulation.
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the n terminal flanking region of the a1 domain regulates the force dependent binding of von willebrand factor to platelet glycoprotein ibα
Journal of Biological Chemistry, 2013Co-Authors: Jing Fei Dong, Miguel A Cruz, Cheng ZhuAbstract:Binding of platelet glycoprotein Ibα (GPIbα) to von Willebrand factor (VWF) initiates platelet adhesion to disrupted vascular surface under arterial blood flow. Flow exerts forces on the platelet that are transmitted to VWF-GPIbα Bonds, which regulate their dissociation. Mutations in VWF and/or GPIbα may alter the mechanical regulation of platelet adhesion to cause hemostatic defects as found in patients with von Willebrand disease (VWD). Using a biomembrane force probe, we observed biphasic force-decelerated (Catch) and force-accelerated (slip) dissociation of GPIbα from VWF. The VWF A1 domain that contains the N-terminal flanking sequence Gln1238–Glu1260 (1238-A1) formed triphasic slip-Catch-slip Bonds with GPIbα. By comparison, using a short form of A1 that deletes this sequence (1261-A1) abolished the Catch Bond, destabilizing its binding to GPIbα at high forces. Importantly, shear-dependent platelet rolling velocities on these VWF ligands in a flow chamber system mirrored the force-dependent single-Bond lifetimes. Adding the Gln1238–Glu1260 peptide, which interacted with GPIbα and 1261-A1 but not 1238-A1, to whole blood decreased platelet attachment under shear stress. Soluble Gln1238–Glu1260 reduced the lifetimes of GPIbα Bonds with VWF and 1238-A1 but rescued the Catch Bond of GPIbα with 1261-A1. A type 2B VWD 1238-A1 mutation eliminated the Catch Bond by prolonging lifetimes at low forces, a type 2M VWD 1238-A1 mutation shifted the respective slip-Catch and Catch-slip transition points to higher forces, whereas a platelet type VWD GPIbα mutation enhanced the Bond lifetime in the entire force regime. These data reveal the structural determinants of VWF activation by hemodynamic force of the circulation. Background: Hemodynamic force-regulated VWF-GPIbα interaction mediates platelet adhesion during the early stage of hemostatic and thrombotic processes. Results: The VWF-A1 N-terminal sequence impedes the VWF-GPIbα interaction at low forces but stabilizes it as force increases. Conclusion: The interplay between force and A1 N-terminal sequence regulates the VWF-GPIbα interaction. Significance: Force regulation is crucial to the balance of the platelet adhesive function in hemostasis and thrombosis.
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forcing switch from short to intermediate and long lived states of the αa domain generates lfa 1 icam 1 Catch Bonds
Journal of Biological Chemistry, 2010Co-Authors: Wei Chen, Jizhong Lou, Cheng ZhuAbstract:Binding of lymphocyte function-associated antigen-1 (LFA-1) to intercellular adhesion molecule-1 (ICAM-1) mediates leukocyte adhesion under force. Using a biomembrane force probe capable of measuring single Bond interactions, we showed ICAM-1 binding to LFA-1 at different conformations, including the bent conformation with the lowest affinity. We quantify how force and conformations of LFA-1 regulate its kinetics with ICAM-1. At zero-force, on-rates were substantially changed by conditions that differentially favor a bent or extended LFA-1 with a closed or open headpiece; but off-rates were identical. With increasing force, LFA-1/ICAM-1 Bond lifetimes (reciprocal off-rates) first increased (Catch Bonds) and then decreased (slip Bonds). Three states with distinct off-rates were identified from lifetime distributions. Force shifted the associated fractions from the short- to intermediate- and long-lived states, producing Catch Bonds at low forces, but increased their off-rates exponentially, converting Catch to slip Bonds at high forces. An internal ligand antagonist that blocks pulling of the α7-helix suppressed the intermediate-/long-lived states and eliminated Catch Bonds, revealing an internal Catch Bond between the αA and βA domains. These results elucidate an allosteric mechanism for the mechanochemistry of LFA-1/ICAM-1 binding.
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mechanical switching and coupling between two dissociation pathways in a p selectin adhesion Bond
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Evan Evans, Andrew Leung, Volkmar Heinrich, Cheng ZhuAbstract:Many biomolecular Bonds exhibit a mechanical strength that increases in proportion to the logarithm of the rate of force application. Consistent with exponential decrease in Bond lifetime under rising force, this kinetically limited failure reflects dissocia- tion along a single thermodynamic pathway impeded by a sharp free energy barrier. Using a sensitive force probe to test the leukocyte adhesion Bond P-selectin glycoprotein ligand 1 (PSGL- 1)-P-selectin, we observed a linear increase of Bond strength with each 10-fold increase in the rate of force application from 300 to 30,000 pNsec, implying a single pathway for failure. However, the strength and lifetime of PSGL-1-P-selectin Bonds dropped anom- alously when loaded below 300 pNsec, demonstrating unexpect- edly faster dissociation and a possible second pathway for failure. Remarkably, if first loaded by a ''jump'' in force to 20 -30 pN, the Bonds became strong when subjected to a force ramp as slow as 30 pNsec and exhibited the same single-pathway kinetics under all force rates. Applied in this way, a new ''jumpramp'' mode of force spectroscopy was used to show that the PSGL-1-P-selectin Bond behaves as a mechanochemical switch where force history selects between two dissociation pathways with markedly differ- ent properties. Furthermore, replacing PSGL-1 by variants of its 19-aa N terminus and by the crucial tetrasaccharide sialyl LewisX produces dramatic changes in the failure kinetics, suggesting a structural basis for the two pathways. The two-pathway switch seems to provide a mechanism for the ''Catch Bond'' response observed recently with PSGL-1-P-selectin Bonds subjected to small- constant forces.
Anselmetti Dario - One of the best experts on this subject based on the ideXlab platform.
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Exploring the Sulfatase 1 Catch Bond Free Energy Landscape using Jarzynski's Equality
'Elsevier BV', 2019Co-Authors: Walhorn Volker, Dierks Thomas, Bartz Christian, Moeller Ann-kristin, Anselmetti DarioAbstract:Walhorn V, Moeller A-K, Bartz C, Dierks T, Anselmetti D. Exploring the Sulfatase 1 Catch Bond Free Energy Landscape using Jarzynski's Equality. In: BIOPHYSICAL JOURNAL. Vol 116. Cell Press; 2019: 430A-431A
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Exploring the Sulfatase 1 Catch Bond Free Energy Landscape using Jarzynski's Equality
'Springer Science and Business Media LLC', 2018Co-Authors: Walhorn Volker, Möller Ann-kristin, Dierks Thomas, Bartz Christian, Anselmetti DarioAbstract:Walhorn V, Möller A-K, Bartz C, Dierks T, Anselmetti D. Exploring the Sulfatase 1 Catch Bond Free Energy Landscape using Jarzynski's Equality. Scientific Reports. 2018;8(1): 16849.In non-covalent biological adhesion, molecular Bonds commonly exhibit a monotonously decreasing life time when subjected to tensile forces (slip Bonds). In contrast, Catch Bonds behave counter intuitively, as they show an increased life time within a certain force interval. To date only a hand full of Catch Bond displaying systems have been identified. In order to unveil their nature, a number of structural and phenomenological models have been introduced. Regardless of the individual causes for Catch Bond behavior, it appears evident that the free energy landscapes of these interactions bear more than one binding state. Here, we investigated the Catch Bond interaction between the hydrophilic domain of the human cell surface sulfatase 1 (Sulf1HD) and its physiological substrate heparan sulfate (HS) by atomic force microscopy based single molecule force spectroscopy (AFM-SMFS). Using Jarzynski's equality, we estimated the associated Gibbs free energy and provide a comprehensive thermodynamic and kinetic characterization of Sulf1HD/HS interaction. Interestingly, the binding potential landscape exhibits two distinct potential wells which confirms the recently suggested two state binding. Even though structural data of Sulf1HD is lacking, our results allow to draft a detailed picture of the directed and processive desulfation of HS
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Catch Bond Interaction between Cell-Surface Sulfatase Sulf1 and Glycosaminoglycans
Biophysical Society. Published by Elsevier Inc., 2015Co-Authors: Harder Alexander, Möller Ann-kristin, Milz Fabian, Neuhaus Phillipp, Walhorn Volker, Dierks Thomas, Anselmetti DarioAbstract:AbstractIn biological adhesion, the biophysical mechanism of specific biomolecular interaction can be divided in slip and Catch Bonds, respectively. Conceptually, slip Bonds exhibit a reduced Bond lifetime under increased external force and Catch Bonds, in contrast, exhibit an increased lifetime (for a certain force interval). Since 2003, a handful of biological systems have been identified to display Catch Bond properties. Upon investigating the specific interaction between the unique hydrophilic domain (HD) of the human cell-surface sulfatase Sulf1 against its physiological glycosaminoglycan (GAG) target heparan sulfate (HS) by single molecule force spectroscopy (SMFS), we found clear evidence of Catch Bond behavior in this system. The HD, ∼320 amino acids long with dominant positive charge, and its interaction with sulfated GAG-polymers were quantitatively investigated using atomic force microscopy (AFM) based force clamp spectroscopy (FCS) and dynamic force spectroscopy (DFS). In FCS experiments, we found that the Catch Bond character of HD against GAGs could be attributed to the GAG 6-O-sulfation site whereas only slip Bond interaction can be observed in a GAG system where this site is explicitly lacking. We interpreted the binding data within the theoretical framework of a two state two path model, where two slip Bonds are coupled forming a double-well interaction potential with an energy difference of ΔE ≈ 9 kBT and a compliance length of Δx ≈ 3.2 nm. Additional DFS experiments support this assumption and allow identification of these two coupled slip-Bond states that behave consistently within the Kramers-Bell-Evans model of force-mediated dissociation
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Catch Bond Interaction between Cell-Surface Sulfatase Sulf1 and Glycosaminoglycans
'Elsevier BV', 2015Co-Authors: Harder Alexander, Möller Ann-kristin, Milz Fabian, Neuhaus Phillipp, Walhorn Volker, Dierks Thomas, Anselmetti DarioAbstract:Harder A, Möller A-K, Milz F, et al. Catch Bond Interaction between Cell-Surface Sulfatase Sulf1 and Glycosaminoglycans. Biophysical journal. 2015;108(7):1709-1717.In biological adhesion, the biophysical mechanism of specific biomolecular interaction can be divided in slip and Catch Bonds, respectively. Conceptually, slip Bonds exhibit a reduced Bond lifetime under increased external force and Catch Bonds, in contrast, exhibit an increased lifetime (for a certain force interval). Since 2003, a handful of biological systems have been identified to display Catch Bond properties. Upon investigating the specific interaction between the unique hydrophilic domain (HD) of the human cell-surface sulfatase Sulf1 against its physiological glycosaminoglycan (GAG) target heparan sulfate (HS) by single molecule force spectroscopy (SMFS), we found clear evidence of Catch Bond behavior in this system. The HD, ∼320 amino acids long with dominant positive charge, and its interaction with sulfated GAG-polymers were quantitatively investigated using atomic force microscopy (AFM) based force clamp spectroscopy (FCS) and dynamic force spectroscopy (DFS). In FCS experiments, we found that the Catch Bond character of HD against GAGs could be attributed to the GAG 6-O-sulfation site whereas only slip Bond interaction can be observed in a GAG system where this site is explicitly lacking. We interpreted the binding data within the theoretical framework of a two state two path model, where two slip Bonds are coupled forming a double-well interaction potential with an energy difference of ΔE ≈ 9 kBT and a compliance length of Δx ≈ 3.2 nm. Additional DFS experiments support this assumption and allow identification of these two coupled slip-Bond states that behave consistently within the Kramers-Bell-Evans model of force-mediated dissociation