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. 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 in solution between a class B JDP from yeast, Sis1, and the HSP70-EEVD motif. The EEVD motif binds to multiple sites in Sis1, two of them at the C-terminal domain I (CTDI), the other is a competing interaction between the J-domain and the N-terminal boundary of α-helix 6 (at the GF-region). The interactions at CTDI contributes to the anchoring of HSP70 to Sis1, at site I, and the displacement of the client protein at site II, by competition. 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.