scholarly journals Autoinhibition of Bruton's tyrosine kinase (Btk) and activation by soluble inositol hexakisphosphate

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Qi Wang ◽  
Erik M Vogan ◽  
Laura M Nocka ◽  
Connor E Rosen ◽  
Julie A Zorn ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Cell Function ◽  
Lipid Binding ◽  
Bruton’S Tyrosine Kinase ◽  
Inositol Hexakisphosphate ◽  
Sequence Comparisons ◽  
Bruton's Tyrosine Kinase ◽  
Tec Kinases ◽  
Biochemical Analyses ◽  
A Tec

Bruton's tyrosine kinase (Btk), a Tec-family tyrosine kinase, is essential for B-cell function. We present crystallographic and biochemical analyses of Btk, which together reveal molecular details of its autoinhibition and activation. Autoinhibited Btk adopts a compact conformation like that of inactive c-Src and c-Abl. A lipid-binding PH-TH module, unique to Tec kinases, acts in conjunction with the SH2 and SH3 domains to stabilize the inactive conformation. In addition to the expected activation of Btk by membranes containing phosphatidylinositol triphosphate (PIP3), we found that inositol hexakisphosphate (IP6), a soluble signaling molecule found in both animal and plant cells, also activates Btk. This activation is a consequence of a transient PH-TH dimerization induced by IP6, which promotes transphosphorylation of the kinase domains. Sequence comparisons with other Tec-family kinases suggest that activation by IP6 is unique to Btk.

scholarly journals Structural mechanism for Bruton’s tyrosine kinase activation at the cell membrane

2019 ◽  
Vol 116 (19) ◽  
pp. 9390-9399 ◽  
Author(s):  
Qi Wang ◽  
Yakov Pechersky ◽  
Shiori Sagawa ◽  
Albert C. Pan ◽  
David E. Shaw
Keyword(s):  
Cell Membrane ◽  
Tyrosine Kinase ◽  
B Cell ◽  
Lipid Binding ◽  
Bruton’S Tyrosine Kinase ◽  
Bruton's Tyrosine Kinase ◽  
Structural Mechanism ◽  
Kinase Activation ◽  
Effects Of Ph ◽  
Dynamics Simulations

Bruton’s tyrosine kinase (Btk) is critical for B cell proliferation and activation, and the development of Btk inhibitors is a vigorously pursued strategy for the treatment of various B cell malignancies. A detailed mechanistic understanding of Btk activation has, however, been lacking. Here, inspired by a previous suggestion that Btk activation might depend on dimerization of its lipid-binding PH–TH module on the cell membrane, we performed long-timescale molecular dynamics simulations of membrane-bound PH–TH modules and observed that they dimerized into a single predominant conformation. We found that the phospholipid PIP3 stabilized the dimer allosterically by binding at multiple sites, and that the effects of PH–TH mutations on dimer stability were consistent with their known effects on Btk activity. Taken together, our simulation results strongly suggest that PIP3-mediated dimerization of Btk at the cell membrane is a critical step in Btk activation.

scholarly journals Switch-like activation of Bruton’s tyrosine kinase by membrane-mediated dimerization

2019 ◽  
Vol 116 (22) ◽  
pp. 10798-10803 ◽  
Author(s):  
Jean K. Chung ◽  
Laura M. Nocka ◽  
Aubrianna Decker ◽  
Qi Wang ◽  
Theresa A. Kadlecek ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Membrane Surface ◽  
Critical Role ◽  
Lipid Binding ◽  
Correlation Spectroscopy ◽  
Ligand Concentration ◽  
Activation Mechanism ◽  
Bruton’S Tyrosine Kinase ◽  
Bruton's Tyrosine Kinase ◽  
Kinetic Measurements

The transformation of molecular binding events into cellular decisions is the basis of most biological signal transduction. A fundamental challenge faced by these systems is that reliance on protein–ligand chemical affinities alone generally results in poor sensitivity to ligand concentration, endangering the system to error. Here, we examine the lipid-binding pleckstrin homology and Tec homology (PH-TH) module of Bruton’s tyrosine kinase (Btk). Using fluorescence correlation spectroscopy (FCS) and membrane-binding kinetic measurements, we identify a phosphatidylinositol (3–5)-trisphosphate (PIP3) sensing mechanism that achieves switch-like sensitivity to PIP3 levels, surpassing the intrinsic affinity discrimination of PIP3:PH binding. This mechanism employs multiple PIP3 binding as well as dimerization of Btk on the membrane surface. Studies in live cells confirm that mutations at the dimer interface and peripheral site produce effects comparable to that of the kinase-dead Btk in vivo. These results demonstrate how a single protein module can institute an allosteric counting mechanism to achieve high-precision discrimination of ligand concentration. Furthermore, this activation mechanism distinguishes Btk from other Tec family member kinases, Tec and Itk, which we show are not capable of dimerization through their PH-TH modules. This suggests that Btk plays a critical role in the stringency of the B cell response, whereas T cells rely on other mechanisms to achieve stringency.

scholarly journals Switching immune signals on and off

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Nam Chu ◽  
Philip A Cole
Keyword(s):  
Tyrosine Kinase ◽  
B Cell ◽  
Cell Function ◽  
Bruton’S Tyrosine Kinase ◽  
Bruton's Tyrosine Kinase ◽  
B Cell Function

Bruton's tyrosine kinase, an enzyme that is important for B cell function, can be activated in a number of ways.

scholarly journals Switch-like activation of Bruton’s tyrosine kinase by membrane-mediated dimerization

2018 ◽  
Author(s):  
Jean K. Chung ◽  
Laura M. Nocka ◽  
Qi Wang ◽  
Theresa A. Kadlecek ◽  
Arthur Weiss ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Membrane Surface ◽  
Lipid Binding ◽  
Correlation Spectroscopy ◽  
Coincidence Detection ◽  
Ligand Concentration ◽  
Bruton’S Tyrosine Kinase ◽  
Detection Mechanism ◽  
Bruton's Tyrosine Kinase ◽  
Kinetic Measurements

ABSTRACTThe transformation of molecular binding events into cellular decisions is the basis of most biological signal transduction. A fundamental challenge faced by these systems is that protein-ligand chemical affinities alone generally result in poor sensitivity to ligand concentration, endangering the system to error. Here, we examine the lipid-binding pleckstrin homology and Tec homology (PH-TH) module of Bruton’s tyrosine kinase (Btk) Using fluorescence correlation spectroscopy (FCS) and membrane-binding kinetic measurements, we identify a self-contained phosphatidylinositol (3,4,5)-trisphosphate (PIP3) sensing mechanism that achieves switch-like sensitivity to PIP3 levels, surpassing the intrinsic affinity discrimination of PIP3:PH binding. This mechanism employs multiple PIP3 binding as well as dimerization of Btk on the membrane surface. Mutational studies in live cells confirm that this mechanism is critical for activation of Btk in vivo. These results demonstrate how a single protein module can institute a minimalist coincidence detection mechanism to achieve high-precision discrimination of ligand concentration.

scholarly journals Structural mechanism for Bruton’s tyrosine kinase activation at the cell membrane

2018 ◽  
Author(s):  
Qi Wang ◽  
Yakov Pechersky ◽  
Shiori Sagawa ◽  
Albert C. Pan ◽  
David E. Shaw
Keyword(s):  
Cell Membrane ◽  
Tyrosine Kinase ◽  
B Cell ◽  
Lipid Binding ◽  
Bruton’S Tyrosine Kinase ◽  
Bruton's Tyrosine Kinase ◽  
Structural Mechanism ◽  
Kinase Activation ◽  
Effects Of Ph ◽  
Dynamics Simulations

AbstractBruton’s tyrosine kinase (Btk) is critical for B-cell proliferation and activation, and the development of Btk inhibitors is a vigorously pursued strategy for the treatment of various B-cell malignancies. A detailed mechanistic understanding of Btk activation has, however, been lacking. Here, inspired by a previous suggestion that Btk activation might depend on dimerization of its lipid-binding PH-TH module on the cell membrane, we performed long-timescale molecular dynamics simulations of membrane-bound PH-TH modules and observed that they dimerized into a single predominant conformation. We found that the phospholipid PIP3 stabilized the dimer allosterically by binding at multiple sites, and that the effects of PH-TH mutations on dimer stability were consistent with their known effects on Btk activity. Taken together, our simulation results strongly suggest that PIP3-mediated dimerization of Btk at the cell membrane is a critical step in Btk activation.

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