6jzb | pdb_00006jzb
Structural characterization of DnaJ from Streptococcus pneumonia presents a new tetramer of Hsp40 family
Structural highlights
Function[A0MSU1_STREE] Participates actively in the response to hyperosmotic and heat shock by preventing the aggregation of stress-denatured proteins and by disaggregating proteins, also in an autonomous, DnaK-independent fashion. Unfolded proteins bind initially to DnaJ; upon interaction with the DnaJ-bound protein, DnaK hydrolyzes its bound ATP, resulting in the formation of a stable complex. GrpE releases ADP from DnaK; ATP binding to DnaK triggers the release of the substrate protein, thus completing the reaction cycle. Several rounds of ATP-dependent interactions between DnaJ, DnaK and GrpE are required for fully efficient folding. Also involved, together with DnaK and GrpE, in the DNA replication of plasmids through activation of initiation proteins.[HAMAP-Rule:MF_01152] Publication Abstract from PubMedMolecular chaperones can prevent and repair protein misfolding and aggregation to maintain protein homeostasis in cells. Hsp40 chaperones interact with unfolded client proteins via the dynamic multivalent interaction (DMI) mechanism with their multiple client-binding sites. Here we report that a type I Hsp40 chaperone from Streptococcus pneumonia (spHsp40) forms a concentration-independent polydispersity oligomer state in solution. The crystal structure of spHsp40 determined at 2.75 A revealed that each monomer has a type I Hsp40 structural fold containing a zinc finger domain and C-terminal domains I and II (CTD I and CTD II). Subsequent quaternary structure analysis using a PISA server generated two dimeric models. The interface mutational analysis suggests the conserved C-terminal dimeric motif as a basis for dimer formation and that the novel dimeric interaction between a client-binding site in CTD I and the zinc finger domain promotes the formation of the spHsp40 oligomeric state. In vitro functional analysis demonstrated that spHsp40 oligomer is fully active and possess the optimal activity in stimulating the ATPase activity of spHsp70. The oligomer state of type I Hsp40 and its formation might be important in understanding Hsp40 function and its interaction with client proteins. Structural insights into the formation of oligomeric state by a type I Hsp40 chaperone.,Zhu M, Ou D, Khan MH, Zhao S, Zhu Z, Niu L Biochimie. 2020 Sep;176:45-51. doi: 10.1016/j.biochi.2020.06.009. Epub 2020 Jul, 2. PMID:32621942[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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