Conformational dynamics of FERM-mediated autoinhibition in Pyk2 tyrosine kinase

Pyk2 is a non-receptor tyrosine kinase that evolved from gene duplication of focal adhesion kinase (FAK) and subsequent functional specialization in the brain and hemopoietic cells. Pyk2 shares a domain organization with FAK, with an N-terminal regulatory FERM domain adjoining the kinase domain. FAK regulation involves integrin-mediated membrane clustering to relieve autoinhibitory interactions between FERM and kinase domains. Pyk2 regulation remains cryptic, involving Ca 2+ influx and protein scaffolding. While the mechanism of the FAK FERM domain in autoinhibition is well-established, the regulatory role of the Pyk2 FERM is ambiguous. We probed the mechanisms of FERM-mediated autoinhibition of Pyk2 using hydrogen/deuterium exchange mass spectrometry (HDX-MS) and kinase activity profiling. The results reveal FERM-kinase interfaces responsible for autoinhibition. Pyk2 autoinhibition impacts activation loop conformation. In addition, the autoinhibitory FERM-kinase interface exhibits allosteric linkage with the FERM basic patch conserved in both FAK and Pyk2. Table of Contents graphic