4ab3 | pdb_00004ab3
ATP-triggered molecular mechanics of the chaperonin GroEL
Structural highlights
Function[CH60_ECOLI] Prevents misfolding and promotes the refolding and proper assembly of unfolded polypeptides generated under stress conditions.[HAMAP-Rule:MF_00600] Essential for the growth of the bacteria and the assembly of several bacteriophages. Also plays a role in coupling between replication of the F plasmid and cell division of the cell.[HAMAP-Rule:MF_00600] Publication Abstract from PubMedThe chaperonin GroEL assists the folding of nascent or stress-denatured polypeptides by actions of binding and encapsulation. ATP binding initiates a series of conformational changes triggering the association of the cochaperonin GroES, followed by further large movements that eject the substrate polypeptide from hydrophobic binding sites into a GroES-capped, hydrophilic folding chamber. We used cryo-electron microscopy, statistical analysis, and flexible fitting to resolve a set of distinct GroEL-ATP conformations that can be ordered into a trajectory of domain rotation and elevation. The initial conformations are likely to be the ones that capture polypeptide substrate. Then the binding domains extend radially to separate from each other but maintain their binding surfaces facing the cavity, potentially exerting mechanical force upon kinetically trapped, misfolded substrates. The extended conformation also provides a potential docking site for GroES, to trigger the final, 100 degrees domain rotation constituting the "power stroke" that ejects substrate into the folding chamber. ATP-triggered conformational changes delineate substrate-binding and -folding mechanics of the GroEL chaperonin.,Clare DK, Vasishtan D, Stagg S, Quispe J, Farr GW, Topf M, Horwich AL, Saibil HR Cell. 2012 Mar 30;149(1):113-23. Epub 2012 Mar 22. PMID:22445172[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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