Circular Permutation of a WW Domain: Folding Still Occurs after Excising the Turn of the Folding-Nucleating Hairpin

Abstract

A hyperstable Pin1 WW domain has been circularly permuted via excision of the fold-nucleating turn; it still folds to form the native three-strand sheet and hydrophobic core features. Multiprobe folding dynamics studies of the normal and circularly permuted sequences, as well as their constituent hairpin fragments and comparable-length β-strand-loop-β-strand models, indicate 2-state folding for all topologies. N-terminal hairpin formation is the fold nucleating event for the wild-type sequence; the slower folding circular permutant has a more distributed folding transition state.

Binding interactions of agents that alter α-synuclein aggregation

“…The concentration range examined was 0 – 8 or 0 –20 vol-% HFIP. In most cases, there was an increase in β structure stability observed at 8 or 20 vol-% HFIP as has previously been observed for other β hairpins 63–67 .…”

“…Cyclo-WW2 was prepared by folding-assisted amide formation with cp-WW2 as the substrate. This sequence (cp-WW2) corresponds to a “circular permutation” of the original WW2 sequence which moves the edge-to-face Trp/Trp interaction from a turn-flanking position 64,66 to an end-capping position 63,67 . The NMR diagnostics of an EtF indole/indole cluster (the far upfield shift of Hε3 of the edge-indole) 64–66 were evident in both species, see Supporting Materials.…”

“…The additional β-sheet models examined as potential inhibitors were available from other studies of hairpins with cross-strand aryl clusters flanking a turn (as in WW2) or at the chain termini (as in cp-WW2) appear below. The peptides designated as mWWhp and cp-mWWhp are mutated fragments corresponding to the N-terminal hairpin of the Pin1 WW domain and its circular permutant 67 .…”

A pH Switch for β‐Sheet Protein Folding

“…It is known that turn 1 (T1) is the nucleating turn of this sheet [25] . The WWst29 [25] system was designed in-house, starting as a truncated version of the wild type protein Pin1 with the inclusion of a Trp/Trp aromatic cluster flanking T1.…”

“…It is known that turn 1 (T1) is the nucleating turn of this sheet [25] . The WWst29 [25] system was designed in-house, starting as a truncated version of the wild type protein Pin1 with the inclusion of a Trp/Trp aromatic cluster flanking T1. [25,26] The cross-strand Trp/Trp cluster also reports the stability of the overall structure as the amplitude of a circular dichroic exciton couplet with maximum at 228 nm.…”