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From Proteopedia
The Structure of the complex between Aha1 and HSP90
Structural highlights
FunctionHSP82_YEAST Molecular chaperone that promotes the maturation, structural maintenance and proper regulation of specific target proteins involved in cell cycle control and signal transduction. Undergoes a functional cycle that is linked to its ATPase activity. The nucleotide-free form of the dimer is found in an open conformation in which the N-termini are not dimerized and the complex is ready for client protein binding. Binding of ATP induces large conformational changes, resulting in the formation of a ring-like closed structure in which the N-terminal domains associate intramolecularly with the middle domain and also dimerize with each other, stimulating their intrinsic ATPase activity and acting as a clamp on the substrate. Finally, ATP hydrolysis results in the release of the substrate. This cycle probably induces conformational changes in the client proteins, thereby causing their activation. Interacts dynamically with various co-chaperones that modulate its substrate recognition, ATPase cycle and chaperone function. Required for growth at high temperatures.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHsp90 is a molecular chaperone essential for the activation and assembly of many key eukaryotic signalling and regulatory proteins. Hsp90 is assisted and regulated by co-chaperones that participate in an ordered series of dynamic multiprotein complexes, linked to Hsp90 conformationally coupled ATPase cycle. The co-chaperones Aha1 and Hch1 bind to Hsp90 and stimulate its ATPase activity. Biochemical analysis shows that this activity is dependent on the N-terminal domain of Aha1, which interacts with the central segment of Hsp90. The structural basis for this interaction is revealed by the crystal structure of the N-terminal domain (1-153) of Aha1 (equivalent to the whole of Hch1) in complex with the middle segment of Hsp90 (273-530). Structural analysis and mutagenesis show that binding of N-Aha1 promotes a conformational switch in the middle-segment catalytic loop (370-390) of Hsp90 that releases the catalytic Arg 380 and enables its interaction with ATP in the N-terminal nucleotide-binding domain of the chaperone. Structural basis for recruitment of the ATPase activator Aha1 to the Hsp90 chaperone machinery.,Meyer P, Prodromou C, Liao C, Hu B, Roe SM, Vaughan CK, Vlasic I, Panaretou B, Piper PW, Pearl LH EMBO J. 2004 Mar 24;23(6):1402-10. PMID:15039704[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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