Insights into the molecular mechanism of protein native-like aggregation upon m...

• Author(s): Oliveira, Luís M. A. ; Gomes, Ricardo A. ; Yang, Dennis ; Família, Carlos ; Lages, Ana ; Coelho, Ana V. ; Murphy, Regina M. ; Quintas, Alexandre
• Date: 2013
• Origin: Repositório Comum
• Subject(s): Native-like aggregation; Conformational diseases; Glycation; Methylglyoxal; Cytochrome c
• Document Type: Article
• Language: English

Description

"Protein glycation induces structural and stability changes that impair protein function, and is associated with several human neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease and Familial Amyloidotic Polyneuropathy. Recently we have shown that methylglyoxal induces and stabilizes the formation of small native-like aggregates in the amyloidogenic protein insulin and the same was previously shown for α-synuclein. However, the fundamental biophysical mechanism underlying such methylglyoxal-induced protein aggregation is not yet fully understood. In this study, we used the model protein cytochrome c to characterize the specific glycation targets and to investigate the glycation effects on protein structure, stability and aggregation. Methylglyoxal was found modify cytochrome c in a single residue and to induce the formation of cytochrome c native-like aggregates. Additionally, it is shown that methylglyoxal glycation of cytochrome c also results in the formation of a partially unfolded species. Interestingly, the formation of this partially unfolded species is not implicated in the aggregation process, a clear difference from amyloid fibril mechanisms that involve partially or totally unfolded intermediates. Equilibrium-unfolding experiments using guanidinium hydrochloride shows that glycation strongly reduces cytochrome c conformational stability. This reduction is balanced by aggregation that increases conformational stability. The data collected from analytical and spectroscopic techniques along with kinetic analysis based on least-squares parameter fitting and statistical model discrimination permitted the proposal of a comprehensive thermodynamic and kinetic model for native-like aggregation of methylglyoxal glycated cytochrome c."