The C-terminal helices of heat shock protein 70 are essential for J-domain binding and ATPase activation.
The J-domain co-chaperones work together with the heat shock protein 70 (HSP70) chaperone to regulate many cellular events, but the mechanism underlying the J-domain-mediated HSP70 function remains elusive. We studied the interaction between human-inducible HSP70 and Homo sapiens J-domain protein (HSJ1a), a J domain and UIM motif-containing co-chaperone. The J domain of HSJ1a shares a conserved structure with other J domains from both eukaryotic and prokaryotic species, and it mediates the interaction with and the ATPase cycle of HSP70. Our in vitro study corroborates that the N terminus of HSP70 including the ATPase domain and the substrate-binding β-subdomain is not sufficient to bind with the J domain of HSJ1a. The C-terminal helical α-subdomain of HSP70, which was considered to function as a lid of the substrate-binding domain, is crucial for binding with the J domain of HSJ1a and stimulating the ATPase activity of HSP70. These fluctuating helices are likely to contribute to a proper conformation of HSP70 for J-domain binding other than directly bind with the J domain. Our findings provide an alternative mechanism of allosteric activation for functional regulation of HSP70 by its J-domain co-chaperones.
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Xue-Chao
XC
Gao
Chen-Jie
CJ
Zhou
Zi-Ren
ZR
Zhou
Meng
M
Wu
Chun-Yang
CY
Cao
Hong-Yu
HY
Hu
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000494:Allosteric Regulation; D004789:Enzyme Activation; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012996:Solutions
D018840:HSP70 Heat-Shock Proteins; D012996:Solutions; D000251:Adenosine Triphosphatases