What is the biological relevance of the specific bond properties revealed by single‐molecule studies?

Robert, P.; Benoliel, Anne‐Marie; Pierrès, Anne; Bongrand, Pierre

doi:10.1002/jmr.827

Cited by 46 publications

(55 citation statements)

References 127 publications

(176 reference statements)

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“…On-rates measured using SPR were converted to k on on the membrane by assuming (i) that k off of membrane-bound TCRs binding pMHCs are identical to SPR measurements and (ii) that the K D s of membrane-bound TCRs engaging pMHCs are proportional to SPR-measured affinities, as done in our analysis of receptor occupancy. Because of limited data, it is generally difficult to convert SPR-measured k on directly to k on on the membrane (35,36). We discuss sensitivity to the assumptions in SI Text.…”

Section: Rebinding Of Tcrs To Pmhcs Uniquely Explains How Fast Kineticmentioning

confidence: 99%

Fast on-rates allow short dwell time ligands to activate T cells

Govern¹,

Paczosa

Chakraborty

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

143

167

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Two contrasting theories have emerged that attempt to describe T-cell ligand potency, one based on the t 1/2 of the interaction and the other based on the equilibrium affinity (K D ). Here, we have identified and studied an extensive set of T-cell receptor (TCR)-peptide-MHC (pMHC) interactions for CD4 + cells that have differential K D s and kinetics of binding. Our data indicate that ligands with a short t 1/2 can be highly stimulatory if they have fast onrates. Simple models suggest these fast kinetic ligands are stimulatory because the pMHCs bind and rebind the same TCR several times. Rebinding occurs when the TCR-pMHC on-rate outcompetes TCR-pMHC diffusion within the cell membrane, creating an aggregate t 1/2 (t a ) that can be significantly longer than a single TCRpMHC encounter. Accounting for t a , ligand potency is K D -based when ligands have fast on-rates (k on ) and t 1/2 -dependent when they have slow k on . Thus, TCR-pMHC k on allow high-affinity short t 1/2 ligands to follow a kinetic proofreading model.T cell receptors (TCRs) expressed on T cells bind host MHC proteins presenting both self-and foreign pathogen-derived peptides (pMHCs). Depending on the signal emanating from these interactions, diverse biological outcomes ensue. In the thymus, these TCR-pMHC-mediated signals shape the specificity of the mature T-cell repertoire and prevent overtly self-reactive T cells from escaping (1). In the periphery, naive T cells require continual TCR engagement with self-pMHC complexes to receive a homeostatic survival signal, whereas engagements with foreign peptides induce rapid T-cell division and the acquisition of effector functions (2). How T cells interpret the interaction between their TCR and pMHC ligands leading to these different biological outcomes is greatly debated.Two competing models of T-cell activation have been proposed, with ligand potency being a function of TCR-pMHC equilibrium affinity (K D ) (3-7) or t 1/2 (8-11). Evidence supporting K D -based receptor occupancy models of TCR signaling comes from sets of ligands that show a correlation between the K D and ligand potency (3, 5) and from the fact that ligands induce qualitatively distinct biological outcomes depending on their concentration (12).In sharp contrast to receptor occupancy models, t 1/2 -based kinetic proofreading models hypothesize that the TCR must be engaged long enough to complete a series of signaling events, including coreceptor recruitment and TCR phosphorylation (13). Increases in the t 1/2 of the TCR-pMHC engagement raise the probability that any single TCR-pMHC engagement will surpass the threshold amount of time required to initiate T-cell activation (14). Recently, this threshold amount of time has been predicted to be at least 2 s (9, 15). Whether there is, in addition, an optimal t 1/2 that balances these kinetic proofreading requirements and the serial triggering of TCRs has been debated (16,17).Further evidence supporting t 1/2 -based kinetic proofreading models arises from the discovery of antagonist pMHC l...

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Section: Rebinding Of Tcrs To Pmhcs Uniquely Explains How Fast Kineticmentioning

confidence: 99%

Fast on-rates allow short dwell time ligands to activate T cells

Govern¹,

Paczosa

Chakraborty

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

143

167

View full text Add to dashboard Cite

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“…The Bell model (4), which has been successfully applied to analyze the binding kinetics of many molecular pairs (8,17,18,41,42), has become the standard model to analyze single-molecule force spectroscopy data (48). Here, it was exploited to characterize the micromechanical and kinetic properties of a single gp120-CD4 bond formed between cell and virion during their initial interaction.…”

Section: Ccr5mentioning

confidence: 99%

Monitoring Early Fusion Dynamics of Human Immunodeficiency Virus Type 1 at Single-Molecule Resolution

Dobrowsky

Zhou

Sun

et al. 2008

J Virol

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The fusion of human immunodeficiency virus type 1 (HIV-1) to host cells is a dynamic process governed by the interaction between glycoproteins on the viral envelope and the major receptor, CD4, and coreceptor on the surface of the cell. How these receptors organize at the virion-cell interface to promote a fusion-competent site is not well understood. Using single-molecule force spectroscopy, we map the tensile strengths, lifetimes, and energy barriers of individual intermolecular bonds between CCR5-tropic HIV-1 gp120 and its receptors CD4 and CCR5 or CXCR4 as a function of the interaction time with the cell. According to the Bell model, at short times of contact between cell and virion, the gp120-CD4 bond is able to withstand forces up to 35 pN and has an initial lifetime of 0.27 s and an intermolecular length of interaction of 0.34 nm. The initial bond also has an energy barrier of 6.7 k B T (where k B is Boltzmann's constant and T is absolute temperature). However, within 0.3 s, individual gp120-CD4 bonds undergo rapid destabilization accompanied by a shortened lifetime and a lowered tensile strength. This destabilization is significantly enhanced by the coreceptor CCR5, not by CXCR4 or fusion inhibitors, which suggests that it is directly related to a conformational change in the gp120-CD4 bond. These measurements highlight the instability and low tensile strength of gp120-receptor bonds, uncover a synergistic role for CCR5 in the progression of the gp120-CD4 bond, and suggest that the cell-virus adhesion complex is functionally arranged about a long-lived gp120-coreceptor bond.

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“…Such a difference among the affinity and the thermodynamic parameters has already been reported and attributed to the fact that some receptors might form rapidly fairly transient bonds, while others with similar affinity might require higher amounts of time to form durable bonds. 49 In summary, these new insights into kinetics and energy landscape of the MDM2-MDM4 complex may contribute to further investigation on the ternary complex formed by the MDM2-MDM4 heterodimer and p53 and, more importantly, could be of significant help in designing specific antagonists that could prevent the formation of the MDM2-MDM4 complex, with subsequent restoration of the p53 oncosuppressive function.…”

Section: Discussionmentioning

confidence: 91%

MDM2–MDM4 molecular interaction investigated by atomic force spectroscopy and surface plasmon resonance

Moscetti

Teveroni

Moretti

et al. 2016

IJN

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Murine double minute 2 (MDM2) and 4 (MDM4) are known as the main negative regulators of p53, a tumor suppressor. They are able to form heterodimers that are much more effective in the downregulation of p53. Therefore, the MDM2–MDM4 complex could be a target for promising therapeutic restoration of p53 function. To this aim, a deeper understanding of the molecular mechanisms underlining the heterodimerization is needed. The kinetic and thermodynamic characterization of the MDM2–MDM4 complex was performed with two complementary approaches: atomic force spectroscopy and surface plasmon resonance. Both techniques revealed an equilibrium dissociation constant ( K D ) in the micromolar range for the MDM2–MDM4 heterodimer, similar to related complexes involved in the p53 network. Furthermore, the MDM2–MDM4 complex is characterized by a relatively high free energy, through a single energy barrier, and by a lifetime in the order of tens of seconds. New insights into the MDM2–MDM4 interaction could be highly important for developing innovative anticancer drugs focused on p53 reactivation.

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What is the biological relevance of the specific bond properties revealed by single‐molecule studies?

Cited by 46 publications

References 127 publications

Fast on-rates allow short dwell time ligands to activate T cells

Fast on-rates allow short dwell time ligands to activate T cells

Monitoring Early Fusion Dynamics of Human Immunodeficiency Virus Type 1 at Single-Molecule Resolution

MDM2–MDM4 molecular interaction investigated by atomic force spectroscopy and surface plasmon resonance

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What is the biological relevance of the specific bond properties revealed by single‐molecule studies?

Cited by 46 publications

References 127 publications

Fast on-rates allow short dwell time ligands to activate T cells

Fast on-rates allow short dwell time ligands to activate T cells

Monitoring Early Fusion Dynamics of Human Immunodeficiency Virus Type 1 at Single-Molecule Resolution

MDM2&ndash;MDM4 molecular interaction investigated by atomic force spectroscopy and surface plasmon resonance

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Product

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MDM2–MDM4 molecular interaction investigated by atomic force spectroscopy and surface plasmon resonance