Differential interactions of α-synuclein conformers affect refolding and activity of proteins

Abstract

The accumulation of protein aggregates as intracellular inclusions interferes with cellular protein homeostasis leading to protein aggregation diseases. Protein aggregation results in the formation of several protein conformers including oligomers and fibrils, where, each conformer has its own structural characteristic and proteotoxic potential. The present study explores the effect of alpha-synuclein (α-syn) conformers on the activity and spontaneous refolding of firefly luciferase. Of the different conformers, α-syn monomers delayed the inactivation of luciferase under thermal stress conditions and enhanced the spontaneous refolding of luciferase. In contrast, the α-syn oligomers and fibrils adversely affected luciferase activity and refolding, where, the oligomers inhibited spontaneous refolding, while a pronounced effect on the inactivation of native luciferase was observed in the case of fibrils. These results indicate that the oligomers and fibrils of α-syn interfere with the refolding of luciferase and promote its misfolding and aggregation. The study reveals the differential propensities of various conformers of a pathologically relevant protein in causing inactivation, structural modifications and misfolding of other proteins, consequently resulting in altered protein homeostasis.

Alpha-synuclein null mutation exacerbates the phenotype of a model of Menkes disease in female mice

“…Over-expression of wild type human SNCA has been shown to rescue the phenotypes of mice lacking the synaptic chaperone cysteine string protein suggesting a direct or indirect interaction between these proteins 32 . In other studies, Snca has also been shown to enhance SNARE assembly at the synapse in mice and additional mechanisms of toxicity, including inhibition of ER to Golgi trafficking, have also been proposed 23,[25][26][27][28][33][34][35][36] . Other functions of SNCA, in mitochondrial dynamics and structure, regulation of gene expression, epigenetic programming, nuclear transport, neuron survival, cytoskeletal stabilization and DNA repair, have also been reported (Table 1).…”

“…The basis of SNCA toxicity in PD is not well understood; human mutations that have been identified include both loss-of-function (rare missense mutations) and gainof-function (numerical variant) mutations [20][21][22][23] . One potential mechanism for toxicity includes a slow build-up of a distinct wildtype or mutant oligomer; 24 however, the mechanism and identity of the toxic form is not known and continues to be a subject of debate 23,[25][26][27][28] . Clearly, SNCA can form a variety of oligomeric structures, including the fibrils found in Lewy bodies.…”

Synucleins: New Data on Misfolding, Aggregation and Role in Diseases

“…Interestingly α-synuclein monomers, oligomers and fibrils exert a differential effect on the folding and refolding of other proteins. Bagree et al [ 45 ] examined their influence on the conformation, enzymatic activity and other properties of firefly luciferase. α-Synuclein monomers delayed the inactivation of luciferase under thermal stress conditions and enhanced the spontaneous refolding, whereas oligomers and fibrils adversely influenced luciferase activity and refolding.…”

Conformation-Selective Ultraviolet–Ultraviolet Hole Burning Spectra of Ubiquitin Ions in a Cryogenic Ion Trap

“…X-ray crystallography, nuclear magnetic resonance spectroscopy, and cryo-electron microscopy have been used to experimentally determine protein structures. − Nevertheless, these techniques primarily provide the most prevalent structures of proteins under specific experimental conditions, often overlooking the coexistence of their structural isomers. Although these isomers may be of minor significance in a cell, under certain circumstances, they may transform into misfolded conformations, ultimately giving rise to pathogenic proteins such as oligomers, fibrils, or aggregates. , …”

“…Although these isomers may be of minor significance in a cell, under certain circumstances, they may transform into misfolded conformations, ultimately giving rise to pathogenic proteins such as oligomers, fibrils, or aggregates. 7,8 The presence of structural isomers of proteins has been demonstrated in the gas phase by ion mobility mass spectrometry (IMS). 9 This methodology provides information on the relative abundance and overall structures of these isomers by comparing the experimental collision cross sections (CCS) with theoretical ones.…”