Structural and dynamical basis for the interaction of HSP70-EEVD with JDP Sis1

Abstract

Protein folding, refolding and disaggregation are facilitated by the binding and releasing activity of HSP70 proteins. Such activity is aided by J-domain proteins (JDPs, DNAJs or HSP40s) that stimulate the ATPase activity of HSP70 and stabilize complexes between HSP70 and nonnative proteins. The C-terminus EEVD motif of HSP70 interacts with client proteins and with JDPs. Deletion of the EEVD disrupts the ability of HSP70 to associate with class B JDPs. A new understanding of the EEVD interaction with a JDP arises from the results of this work, which gives a detailed NMR characterization of the dynamics and interaction between a class B JDP, Sis1, and the HSP70-EEVD. The EEVD motif binds to multiple sites in Sis1. The interactions at CTDI contribute to the anchoring of HSP70 to Sis1, at site I, and the displacement of the client protein at site II. The competing interaction between the J-domain and the N-terminal boundary of α-helix 6 (at the GF-region) contributes to the interaction of J-domain to HSP70. These results support a mechanism involved in the regulation of the interaction with HSP70 that is autoinhibitory. Finally, a detailed model of the interaction of the EEVD with the J-domain of Sis1 is proposed.