title: Split Renilla luciferase protein fragment-assisted complementation (SRL-PFAC) to characterize Hsp90-Cdc37 complex and identify critical residues in protein/protein interactions.
abstract: Hsp90 requires cochaperone Cdc37 to load its clients to the Hsp90 superchaperone complex. The purpose of this study was to utilize split Renilla luciferase protein fragment-assisted complementation (SRL-PFAC) bioluminescence to study the full-length human Hsp90-Cdc37 complex and to identity critical residues and their contributions for Hsp90/Cdc37 interaction in living cells. SRL-PFAC showed that full-length human Hsp90/Cdc37 interaction restored dramatically high luciferase activity through Hsp90-Cdc37-assisted complementation of the N and C termini of luciferase (compared with the set of controls). Immunoprecipitation confirmed that the expressed fusion proteins (NRL-Hsp90 and Cdc37-CRL) preserved their ability to interact with each other and also with native Hsp90 or Cdc37. Molecular dynamic simulation revealed several critical residues in the two interaction patches (hydrophobic and polar) at the interface of Hsp90/Cdc37. Mutagenesis confirmed the critical residues for Hsp90-Cdc37 complex formation. SRL-PFAC bioluminescence evaluated the contributions of these critical residues in Hsp90/Cdc37 interaction. The results showed that mutations in Hsp90 (Q133A, F134A, and A121N) and mutations in Cdc37 (M164A, R167A, L205A, and Q208A) reduced the Hsp90/Cdc37 interaction by 70-95% as measured by the resorted luciferase activity through Hsp90-Cdc37-assisted complementation. In comparison, mutations in Hsp90 (E47A and S113A) and a mutation in Cdc37 (A204E) decreased the Hsp90/Cdc37 interaction by 50%. In contrast, mutations of Hsp90 (R46A, S50A, C481A, and C598A) and mutations in Cdc37 (C54S, C57S, and C64S) did not change Hsp90/Cdc37 interactions. The data suggest that single amino acid mutation in the interface of Hsp90/Cdc37 is sufficient to disrupt its interaction, although Hsp90/Cdc37 interactions are through large regions of hydrophobic and polar interactions. These findings provides a rationale to develop inhibitors for disruption of the Hsp90/Cdc37 interaction.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Yiqun
authors.initials: Y
authors.lastname: Jiang
authors.forename: Denzil
authors.initials: D
authors.lastname: Bernard
authors.forename: Yanke
authors.initials: Y
authors.lastname: Yu
authors.forename: Yehua
authors.initials: Y
authors.lastname: Xie
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Li
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Burnett
authors.forename: Xueqi
authors.initials: X
authors.lastname: Fu
authors.forename: Shaomeng
authors.initials: S
authors.lastname: Wang
authors.forename: Duxin
authors.initials: D
authors.lastname: Sun
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018833:Chaperonins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005784:Gene Amplification; D005816:Genetic Complementation Test; D005822:Genetic Vectors; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D049410:Luciferases, Renilla / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D048790:Renilla / Q000201:enzymology*; D012680:Sensitivity and Specificity; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; C498362:CDC37 protein, human; D018797:Cell Cycle Proteins; D018841:HSP90 Heat-Shock Proteins; C533585:HSP90AA2P protein, human; D010446:Peptide Fragments; D049410:Luciferases, Renilla; D018833:Chaperonins