Btk SH2-kinase interface is critical for allosteric kinase activation and its targeting inhibits B-cell neoplasms

• Published in: Nature communications 2020-05, Vol.11 (1), p.2319-15, Article 2319
• Main Authors: Duarte, Daniel P., Lamontanara, Allan J., La Sala, Giuseppina, Jeong, Sukyo, Sohn, Yoo-Kyoung, Panjkovich, Alejandro, Georgeon, Sandrine, Kükenshöner, Tim, Marcaida, Maria J., Pojer, Florence, De Vivo, Marco, Svergun, Dmitri, Kim, Hak-Sung, Dal Peraro, Matteo, Hantschel, Oliver
• Format: Article
• Language: English
• Subjects: 13/1; 13/95; 631/154/555; 631/45/535/1266; 631/67/1990/291; 96; 96/31; Agammaglobulinaemia Tyrosine Kinase - genetics; Agammaglobulinaemia Tyrosine Kinase - metabolism; Agammaglobulinemia; Allosteric properties; Blotting, Western; Bruton's tyrosine kinase; Cell activation; Cell proliferation; Cell Survival - genetics; Cell Survival - physiology; Circular Dichroism; Crystallography, X-Ray - methods; Enzyme inhibitors; Flow Cytometry; HEK293 Cells; Humanities and Social Sciences; Humans; Immunoblotting; Immunoprecipitation; Kinases; Lymphocytes B; Lymphoma - genetics; Lymphoma - metabolism; Molecular dynamics; Molecular Dynamics Simulation; multidisciplinary; Mutagenesis, Site-Directed; Mutation; Mutation - genetics; Neoplasia; Neoplasms; Protein-tyrosine kinase; Science; Science (multidisciplinary); Signaling; Small angle X ray scattering; Tumors; Tyrosine; X-linked agammaglobulinemia; X-ray scattering
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-16128-5

Bruton’s tyrosine kinase (Btk) is critical for B-cell maturation and activation. Btk loss-of-function mutations cause human X-linked agammaglobulinemia (XLA). In contrast, Btk signaling sustains growth of several B-cell neoplasms which may be treated with tyrosine kinase inhibitors (TKIs). Here, we uncovered the structural mechanism by which certain XLA mutations in the SH2 domain strongly perturb Btk activation. Using a combination of molecular dynamics (MD) simulations and small-angle X-ray scattering (SAXS), we discovered an allosteric interface between the SH2 and kinase domain required for Btk activation and to which multiple XLA mutations map. As allosteric interactions provide unique targeting opportunities, we developed an engineered repebody protein binding to the SH2 domain and able to disrupt the SH2-kinase interaction. The repebody prevents activation of wild-type and TKI-resistant Btk, inhibiting Btk-dependent signaling and proliferation of malignant B-cells. Therefore, the SH2-kinase interface is critical for Btk activation and a targetable site for allosteric inhibition. Constitutive Btk signaling drives several B-cell cancers. Here the authors demonstrate key allosteric intramolecular interactions between the SH2 domain and the kinase domain of Btk, and propose an alternative approach for inhibition of both wild-type and tyrosine kinase inhibitor-resistant Btk.