Fig. 4: Structural basis for CHIP binding to tauC3 and inhibition by phosphorylation.
From: Phosphorylation of tau at a single residue inhibits binding to the E3 ubiquitin ligase, CHIP
A 1.8 Å crystal structure of the CHIP TPR domain bound to a 10-mer tauC3 C-terminal peptide. The CHIP TPR domain is depicted in gray, while the tauC3 peptide is in yellow. Helices 1-7 of the CHIP TPR domain are numbered H1-H7. B Close-up view of interactions of tauC3 D421 and C-terminus with CHIP carboxylate-clamp residues K95, N65, N35, and K30. C Close-up view of interaction of tauC3 D418 with CHIP carboxylate-clamp residue K72. D Close-up view of interactions of tauC3 S416 with CHIP carboxylate-clamp residue D134 and proximity to CHIP F131. E Apparent melting temperatures (Tmapp) of CHIP WT or mutants in the absence or presence of 10-mer tau peptides as derived from DSF experiments. Error bars represent SD. (n = 4 technical replicates). F Competition FP experiment showing displacement of fluorescent tracer from WT or D134A CHIP TPR domain by tauC3 pS416 10-mer peptide. Samples were performed in technical quadruplicate and normalized to DMSO control. G Inhibition constants for tauC3 pS416 peptide for WT or D134A CHIP as derived from (F). Error bars represent SD. H In vitro ubiquitination of tau proteoforms by WT or D134A CHIP. Samples were collected at the denoted timepoints, quenched in SDS-PAGE loading buffer, and analyzed by western blot.
