Protein glycosylation is a ubiquitous post-translational modification that regulates the folding and function of many proteins. Misfolding of protein monomers and their toxic aggregation are the hallmark of many prevalent diseases. Thus, understanding the role of glycans in protein aggregation is highly important and could contribute both to unraveling the pathology of protein misfolding diseases as well as providing a means for modifying their course for therapeutic purposes. Using β-O-linked glycosylated variants of the highly studied Tau-derived hexapeptide motif VQIVYK, which served as a simplified amyloid model, we demonstrate that amyloid formation and toxicity can be strongly attenuated by a glycan unit, depending on the nature of the glycan itself. Importantly, we show for the first time that not only do glycans hinder self-aggregation, but the glycosylated peptides are capable of inhibiting aggregation of the non-modified corresponding amyloid scaffold.
Aggregation and accumulation of amyloid β and tau proteins to plaques and neurofibrillary tangles are the key pathogenic events in Alzheimer's disease. Here, we studied the capability of the cyclic d,l-α-peptide CP-2 as a conformational inhibitor of different amyloids to cross-interact with tau-derived AcPHF6 peptide and inhibit its aggregation, membrane perturbation and toxicity.
Protein phosphorylation and O-GlcNAcylation are very common nucleoplasmic post-translational modifications. Mono-addition of either the phosphate or the O-GlcNAc group were shown to inhibit the self-aggregation of amyloidogenic proteins and peptides, which is the hallmark of various protein misfolding diseases. However, their comparable effect upon co-incubation with a native non-modified amyloid scaffold has not been reported. O-linked glycans and phosphate variants of the tau protein-derived VQIVYK hexapeptide motif were generated as a simplified amyloid scaffold model and demonstrate that, while self-aggregation can be attenuated by either a single glycan or a phosphate unit, only co-incubation with the O-GlcNAc variant inhibits aggregation of the native peptide. These results shed light on the role of post-translational modifications in protein aggregation and suggest a novel therapeutic approach to protein misfolding diseases.
Amyloid formation is attenuated by a single glycan unit. Using β‐O‐linked glycosylated variants of the Tau‐derived hexapeptide motif, VQIVYK, which served as a simplified amyloid model scaffold, it is demonstrated that amyloid formation and toxicity can be strongly attenuated by a glycan unit, depending on the nature of the glycan itself. Moreover, the glycosylated peptides inhibit aggregation of the corresponding non‐modified amyloid scaffold. More information can be found in the Full Paper by D. Segal, S. Rahimipour, E. Gazit et al. on page 5945 ff.
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