Abstract
The versatile functions of the heat shock protein 70 (Hsp70) family of molecular chaperones rely on allosteric interactions between their nucleotide-binding and substrate-binding domains, NBD and SBD. Understanding the mechanism of interdomain allostery is essential to rational design of Hsp70 modulators. Yet, despite significant progress in recent years, how the two Hsp70 domains regulate each other's activity remains elusive. Covariance data from experiments and computations emerged in recent years as valuable sources of information towards gaining insights into the molecular events that mediate allostery. In the present study, conservation and covariance properties derived from both sequence and structural dynamics data are integrated with results from Perturbation Response Scanning and in vivo functional assays, so as to establish the dynamical basis of interdomain signal transduction in Hsp70s. Our study highlights the critical roles of SBD residues D481 and T417 in mediating the coupled motions of the two domains, as well as that of G506 in enabling the movements of the α-helical lid with respect to the β-sandwich. It also draws attention to the distinctive role of the NBD subdomains: Subdomain IA acts as a key mediator of signal transduction between the ATP- and substrate-binding sites, this function being achieved by a cascade of interactions predominantly involving conserved residues such as V139, D148, R167 and K155. Subdomain IIA, on the other hand, is distinguished by strong coevolutionary signals (with the SBD) exhibited by a series of residues (D211, E217, L219, T383) implicated in DnaJ recognition. The occurrence of coevolving residues at the DnaJ recognition region parallels the behavior recently observed at the nucleotide-exchange-factor recognition region of subdomain IIB. These findings suggest that Hsp70 tends to adapt to co-chaperone recognition and activity via coevolving residues, whereas interdomain allostery, critical to chaperoning, is robustly enabled by conserved interactions.
Highlights
The heat shock protein 70 (Hsp70) family of molecular chaperones plays a key role in the quality control of protein folding, as well as in regulation of intracellular trafficking [1,2,3]
Using a combination of experimental and computational methods, including in vivo functional assays, sequence- and structure-based analyses and perturbation response scanning, we identified a network of conserved interactions in subdomain IA of the NBD, which plays a key role in propagating signals between the ATP-binding and substrate-binding sites
Our study reveals that NBD subdomain IA, and in particular a number of highly conserved (V139, D148, K155, R167, N170, E171) or co-evolving (R159, L177) residues therein, serve as mediators of communication between the substrate- and nucleotide-binding sites of the respective SBD and NBD, in addition to their involvement in relaying signals from the DnaJ-binding site to the ATP-binding site
Summary
The heat shock protein 70 (Hsp70) family of molecular chaperones plays a key role in the quality control of protein folding, as well as in regulation of intracellular trafficking [1,2,3]. The versatile functions of Hsp70s rely on the allosteric interaction of their two domains, the ATPase domain, referred to as the nucleotide-binding domain, NBD [6], and the substrate-binding domain, SBD [7]. The ADP produced upon ATP hydrolysis is released and a new ATP molecule binds (BRC passage); nucleotide exchange is assisted by a nucleotide exchange factor (NEF, co-chaperone GrpE) [10]. This process enhances the release of substrate (CRD) [3]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
