1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics

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

  1. Qi Wang
  2. Erik M Vogan
  3. Laura M Nocka
  4. Connor E Rosen
  5. Julie A Zorn
  6. Stephen C Harrison
  7. John Kuriyan  Is a corresponding author
  1. Howard Hughes Medical Institute, University of California, Berkeley, United States
  2. Beryllium Inc, United States
  3. University of California, Berkeley, United States
  4. Harvard Medical School, Howard Hughes Medical Institute, United States
https://doi.org/10.7554/eLife.06074
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Cite this article
  1. Qi Wang
  2. Erik M Vogan
  3. Laura M Nocka
  4. Connor E Rosen
  5. Julie A Zorn
  6. Stephen C Harrison
  7. John Kuriyan
(2015)
Autoinhibition of Bruton's tyrosine kinase (Btk) and activation by soluble inositol hexakisphosphate
eLife 4:e06074.
https://doi.org/10.7554/eLife.06074
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Abstract

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.

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Author details

  1. Qi Wang

    Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
    Competing interests
    No competing interests declared.

  2. Erik M Vogan

    Beryllium Inc, Boston, United States
    Competing interests
    No competing interests declared.

  3. Laura M Nocka

    Department of Chemistry, University of California, Berkeley, Berkeley, United States
    Competing interests
    No competing interests declared.

  4. Connor E Rosen

    Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
    Competing interests
    No competing interests declared.

  5. Julie A Zorn

    Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
    Competing interests
    No competing interests declared.

  6. Stephen C Harrison

    Laboratory of Molecular Medicine, Harvard Medical School, Howard Hughes Medical Institute, Boston, United States
    Competing interests
    Stephen C Harrison, Reviewing editor, eLife.

  7. John Kuriyan

    Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
    For correspondence
    jkuriyan@mac.com
    Competing interests
    John Kuriyan, Senior editor, eLife.

Copyright

© 2015, Wang et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Qi Wang
  2. Erik M Vogan
  3. Laura M Nocka
  4. Connor E Rosen
  5. Julie A Zorn
  6. Stephen C Harrison
  7. John Kuriyan
(2015)
Autoinhibition of Bruton's tyrosine kinase (Btk) and activation by soluble inositol hexakisphosphate
eLife 4:e06074.
https://doi.org/10.7554/eLife.06074

Share this article

https://doi.org/10.7554/eLife.06074

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Further reading

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics

    Stimulation of the catalytic activity of the tyrosine kinase Btk by the adaptor protein Grb2

    Laura M Nocka, Timothy J Eisen ... John Kuriyan
    Research Advance

    The Tec-family kinase Btk contains a lipid-binding Pleckstrin homology and Tec homology (PH-TH) module connected by a proline-rich linker to a ‘Src module’, an SH3-SH2-kinase unit also found in Src-family kinases and Abl. We showed previously that Btk is activated by PH-TH dimerization, which is triggered on membranes by the phosphatidyl inositol phosphate PIP3, or in solution by inositol hexakisphosphate (IP6) (Wang et al., 2015, https://doi.org/10.7554/eLife.06074). We now report that the ubiquitous adaptor protein growth-factor-receptor-bound protein 2 (Grb2) binds to and substantially increases the activity of PIP3-bound Btk on membranes. Using reconstitution on supported-lipid bilayers, we find that Grb2 can be recruited to membrane-bound Btk through interaction with the proline-rich linker in Btk. This interaction requires intact Grb2, containing both SH3 domains and the SH2 domain, but does not require that the SH2 domain be able to bind phosphorylated tyrosine residues – thus Grb2 bound to Btk is free to interact with scaffold proteins via the SH2 domain. We show that the Grb2-Btk interaction recruits Btk to scaffold-mediated signaling clusters in reconstituted membranes. Our findings indicate that PIP3-mediated dimerization of Btk does not fully activate Btk, and that Btk adopts an autoinhibited state at the membrane that is released by Grb2.

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics

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

    1. Biochemistry and Chemical Biology

    Disordered proteins interact with the chemical environment to tune their protective function during drying

    Shraddha KC, Kenny H Nguyen ... Thomas C Boothby
    Research Article

    The conformational ensemble and function of intrinsically disordered proteins (IDPs) are sensitive to their solution environment. The inherent malleability of disordered proteins, combined with the exposure of their residues, accounts for this sensitivity. One context in which IDPs play important roles that are concomitant with massive changes to the intracellular environment is during desiccation (extreme drying). The ability of organisms to survive desiccation has long been linked to the accumulation of high levels of cosolutes such as trehalose or sucrose as well as the enrichment of IDPs, such as late embryogenesis abundant (LEA) proteins or cytoplasmic abundant heat-soluble (CAHS) proteins. Despite knowing that IDPs play important roles and are co-enriched alongside endogenous, species-specific cosolutes during desiccation, little is known mechanistically about how IDP-cosolute interactions influence desiccation tolerance. Here, we test the notion that the protective function of desiccation-related IDPs is enhanced through conformational changes induced by endogenous cosolutes. We find that desiccation-related IDPs derived from four different organisms spanning two LEA protein families and the CAHS protein family synergize best with endogenous cosolutes during drying to promote desiccation protection. Yet the structural parameters of protective IDPs do not correlate with synergy for either CAHS or LEA proteins. We further demonstrate that for CAHS, but not LEA proteins, synergy is related to self-assembly and the formation of a gel. Our results suggest that functional synergy between IDPs and endogenous cosolutes is a convergent desiccation protection strategy seen among different IDP families and organisms, yet the mechanisms underlying this synergy differ between IDP families.