Quantitative Analysis of Hsp90-Client Interactions Reveals Principles of Substrate Recognition

• Published in: Cell Vol. 150; no. 5; pp. 987 - 1001
• Main Authors: Taipale, Mikko, Krykbaeva, Irina, Koeva, Martina, Kayatekin, Can, Westover, Kenneth D., Karras, Georgios I., Lindquist, Susan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 31.08.2012
• Subjects: Amino Acid Sequence; Animals; Cell Cycle Proteins - metabolism; Chaperonins - metabolism; HSP90 Heat-Shock Proteins - metabolism; Humans; ligases; Luciferases, Renilla - metabolism; medicine; Models, Molecular; molecular chaperones; Molecular Sequence Data; phosphotransferases (kinases); Protein Interaction Domains and Motifs; Protein Interaction Mapping; Protein Kinases - chemistry; Protein Kinases - metabolism; Protein Stability; Proteome - analysis; quantitative analysis; Receptors, Steroid - metabolism; Sequence Alignment; Thermodynamics; transcription factors; Transcription Factors - metabolism; Ubiquitin-Protein Ligases - metabolism
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/j.cell.2012.06.047

HSP90 is a molecular chaperone that associates with numerous substrate proteins called clients. It plays many important roles in human biology and medicine, but determinants of client recognition by HSP90 have remained frustratingly elusive. We systematically and quantitatively surveyed most human kinases, transcription factors, and E3 ligases for interaction with HSP90 and its cochaperone CDC37. Unexpectedly, many more kinases than transcription factors bound HSP90. CDC37 interacted with kinases, but not with transcription factors or E3 ligases. HSP90::kinase interactions varied continuously over a 100-fold range and provided a platform to study client protein recognition. In wild-type clients, HSP90 did not bind particular sequence motifs, but rather associated with intrinsically unstable kinases. Stabilization of the kinase in either its active or inactive conformation with diverse small molecules decreased HSP90 association. Our results establish HSP90 client recognition as a combinatorial process: CDC37 provides recognition of the kinase family, whereas thermodynamic parameters determine client binding within the family. [Display omitted] ► Hsp90::client interactions quantitatively surveyed in mammalian cells ► Hsp90 binds 60% of kinases, 30% of E3 ligases and 7% of transcription factors ► Cdc37 acts as a kinase-specific adaptor cochaperone ► Within kinases, thermal stability is a major binding determinant The human chaperone HSP90 does not bind specific sequence motifs in its clients, but rather it associates with intrinsically unstable kinases. In addition, the cochaperone CDC37 serves as a specific adaptor for recognizing kinases, indicating that Hsp90 recognizes its clients in a combinatorial manner.