Structural Insights into the Chaperone Activity of the 40-kDa Heat Shock Protein DnaJ

Abstract

Background: DnaJ is an Hsp40 molecular chaperone able to bind and remodel native substrates as RepE, the repressor/ activator of plasmid F replication. Results: We describe the structure of DnaJ bound to RepE and two mutants and the resulting protein conformational changes. Conclusion: DnaJ conformational plasticity allows binding of different substrates. Significance: We present the first structure of an Hsp40 chaperone bound to a client.

Dissection of Structural and Functional Requirements That Underlie the Interaction of ERdj3 Protein with Substrates in the Endoplasmic Reticulum

“…The substratebinding domain of ERdj3 could be readily modeled (16) using the crystal structures of the substrate-binding domains of yeast cytosolic Ydj1p (15), which is very similar to that of Escherichia coli DnaJ (17,24), and the less well conserved yeast Sis1p (14). Their structures suggest that these DnaJ proteins form a dimeric, tong-like structure, which is required for them to grasp and chaperone unfolded substrates (25,26). In the case of Ydj1, a phenylalanine residue in domain III near the C terminus was found to be critical for dimerization (27).…”

Crowding Modulates the Conformation, Affinity, and Activity of the Components of the Bacterial Disaggregase Machinery

“…Excluded volume conditions might also affect to DnaJ conformation, which displays a significant degree of structural flexibility [27,28]. Both crowders induced a loss of ellipticity at 222 nm and 25°C, more pronounced for Dextran 70, which indicates a disordering of the protein secondary structure at low temperature.…”

ArHsp40, a type 1 J-domain protein, is developmentally regulated and stress inducible in post-diapause Artemia franciscana

“…Sequence alignment and protein modeling showed that ArHsp40 was similar to Hsp40s from other species suggesting that it functions in the same way. Hsp40s serve as molecular chaperones, and they transport bound substrates to Hsp70 for folding and/or degradation, processes involving the stimulation of Hsp70 ATPase by Hsp40 (Ahmad et al 2011;Carmel et al 2011;Baaklini Borges et al 2012;Torrente and Shorter 2013;Summers et al 2013;Tiwari et al 2013;Cuéllar et al 2013;Reidy et al 2014).…”

“…functionally dissimilar zinc-binding sites and is potentially involved in substrate interaction (Linke et al 2003;Tiwari et al 2013), and a carboxyl-terminal area that in cooperation with other domains combines with substrate (Lu and Cyr 1998a, b;Cuéllar et al 2013;Tiwari et al 2013). Type II Jdomain proteins resemble type I but lack the zinc-binding domain.…”

“…J-domain proteins, some of which are stress inducible, possess chaperone activity in their own right, interacting with substrate proteins and protecting them from irreversible denaturation before transport to Hsp70 and folding (Lu and Cyr 1998a, b;Li et al 2009;Kampinga and Craig 2010;Ahmad et al 2011;Baaklini et al 2012;Borges et al 2012;Cuéllar et al 2013;Tiwari et al 2013;Ludewig et al 2015). J-domain proteins activate the ATPase of Hsp70 thereby favoring strong interaction of Hsp70 with substrates which promotes the folding of nascent and partially denatured proteins (Mayer and Bukau 2005;Vos et al 2008).…”