PrP charge structure encodes interdomain interactions

Abstract

Almost all proteins contain charged residues, and their chain distribution is tailored to fulfill essential ionic interactions for folding, binding and catalysis. Among proteins, the hinged two-domain chain of the cellular prion protein (PrPC) exhibits a peculiar charge structure with unclear consequences in its structural malleability. To decipher the charge design role, we generated charge-reverted mutants for each domain and analyzed their effect on conformational and metabolic features. We found that charges contain the information for interdomain interactions. Use of dynamic light scattering and thermal denaturation experiments delineates the compaction of the α-fold by an electrostatic compensation between the polybasic 23–30 region and the α3 electronegative surface. This interaction increases stability and disfavors fibrillation. Independently of this structural effect, the N-terminal electropositive clusters regulate the α-cleavage efficiency. In the fibrillar state, use of circular dichroism, atomic-force and fluorescence microscopies reveal that the N-terminal positive clusters and the α3 electronegative surface dictate the secondary structure, the assembly hierarchy and the growth length of the fibril state. These findings show that the PrP charge structure functions as a code set up to ensure function and reduce pathogenic routes.

Interaction between Prion Protein's Copper-Bound Octarepeat Domain and a Charged C-Terminal Pocket Suggests a Mechanism for N-Terminal Regulation

“…Recent analyses suggest that this cis interaction may be mediated by electrostatic charge complementarity between the two domains (Martínez et al, 2015), as well as by metal binding to the N-terminal OR (Spevacek et al, 2013; Thakur et al, 2011). However, little in the way of structural information exists regarding interdomain contact, particularly with regard to the Cu 2+ -bound protein.…”

“…Electrostatic interaction between positive charges of the N-terminal domain and negative charges of the globular domain surface are known to promote cis interaction in PrP (Martínez et al, 2015; Spevacek et al, 2013; Thakur et al, 2011). Here we show that OR-bound Cu 2+ participates directly in the stabilization of interdomain structure through electrostatic interaction with acidic residues on helix 3.…”

“…The potential significance of cis interactions in PrP C processing, functional regulation, and prion disease progression is prompting further investigation into the protein’s tertiary structure. Thus far, studies examining cis interaction have focused on the effects of intrinsic PrP C charge clusters and physiologic Zn 2+ ions (Martínez et al, 2015; Spevacek et al, 2013). …”

The amyloid fold of Gad m 1 epitopes governs IgE binding

“…AFM images were recorded in a MultiMode Veeco microscope and analyzed using WSxM (Nanotec), as previously described3658.…”

Amyloid Assembly Endows Gad m 1 with Biomineralization Properties

“…properties such as formation kinetics, morphology and stability [28]. Therefore, modification of Gad 64 m 1 chain may allow the generation of distinct amyloids to evaluate the biomineralization activity.…”