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Alag, R.

Publications and source records attributed to Alag, R..

2 recordsLinked to original sources

Modulation of liposome membranes by the C-terminal domain of the coronavirus envelope protein

The coronavirus envelope (E) protein is a viroporin that plays a key role in viral assembly, release, budding and pathogenesis. E protein forms oligomeric ion channels that can activate immune responses. However, high-resolution structural data for its extramembrane domains is limited. The C-terminal domain of SARS-CoV has been shown previously to form amyloid fibers, and here we show that these fibers can modulate the shape of liposomes. The propensity to form fibrils, and their effect on liposomes, was examined for sequences belonging to the four clades of coronaviruses. Electron microscopy data shows that the C-terminal domain in E protein adopts a filamentous structure. These findings demonstrate the potential of these peptides to modulate membranes, providing a possible mechanism by which E protein interacts with membranes in the host cell.

biophysics↗

Liquid-Liquid Phase Separation Protects Amyloidogenic and Aggregation-Prone Peptides in Heterologous Expression Systems

Studying pathogenic effects of amyloids requires homogeneous amyloidogenic peptide samples. Recombinant production of these peptides is challenging due to their susceptibility to aggregation and chemical modifications. Thus, chemical synthesis is primarily used to produce amyloidogenic peptides suitable for high resolution structural studies. Here, we exploited the shielded environment of protein condensates formed via liquid-liquid phase separation (LLPS) as a protective mechanism against premature aggregation. We designed a fusion protein tag undergoing LLPS in E. coli and linked it to highly amyloidogenic peptides, including A{beta} amyloid. We find that the fusion proteins form membraneless organelles during overexpression and remain soluble. We also developed a facile purification method of functional A{beta} peptides free of chromatography steps. The strategy exploiting LLPS can be applied to other amyloidogenic, hydrophobic, and repetitive peptides that are otherwise difficult to produce.

molecular biology↗