Dataset Information

Amyloid fibrillation of insulin under water-limited conditions.

ABSTRACT: Amyloid fibrillation in water-organic mixtures has been widely studied to understand the effect of protein-solvent interactions on the fibrillation process. In this study, we monitored insulin fibrillation in formamide and its methyl derivatives (formamide, N-methyl formamide, N,N-dimethyl formamide) in the presence and absence of water. These model solvent systems mimic the cellular environment by providing denaturing conditions and a hydrophobic environment with limited water content. Thioflavin T (ThT) assay revealed that binary mixtures of water with formamide and its methyl derivatives enhanced fibrillation rates and ?-sheet abundance, whereas organic solvents suppressed insulin fibrillation. We utilized solution small-angle x-ray scattering (SAXS) and differential scanning calorimetry (DSC) to investigate the correlation between protein-solvent interactions and insulin fibrillation. SAXS experiments combined with simulated annealing of the protein indicated that the degree of denaturation of the hydrophobic core region at residues B11-B17 determines the fibrillation rate. In addition, DSC experiments suggested a crucial role of hydrophobic interactions in the fibrillation process. These results imply that an environment with limited water, which imitates a lipid membrane system, accelerates protein denaturation and the formation of intermolecular hydrophobic interactions during amyloid fibrillation.

SUBMITTER: Choi TS

PROVIDER: S-EPMC4213668 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Amyloid fibrillation of insulin under water-limited conditions.

Choi Tae Su TS Lee Jong Wha JW Jin Kyeong Sik KS Kim Hugh I HI

Biophysical journal 20141001 8

Amyloid fibrillation in water-organic mixtures has been widely studied to understand the effect of protein-solvent interactions on the fibrillation process. In this study, we monitored insulin fibrillation in formamide and its methyl derivatives (formamide, N-methyl formamide, N,N-dimethyl formamide) in the presence and absence of water. These model solvent systems mimic the cellular environment by providing denaturing conditions and a hydrophobic environment with limited water content. Thioflav ...[more]

PMID: 25418175

Similar Datasets

Project description:Nanoparticles attract much interest as fluorescent labels for diagnostic and therapeutic tools, although their applications are often hindered by size- and shape-dependent cytotoxicity. This cytotoxicity is related not only to the leak of toxic metals from nanoparticles into a biological solution, but also to molecular cytotoxicity effects determined by the formation of a protein corona, appearance of an altered protein conformation leading to exposure of cryptic epitopes and cooperative effects involved in the interaction of proteins and peptides with nanoparticles. In the last case, nanoparticles may serve, depending on their nature, as centers of self-association or fibrillation of proteins and peptides, provoking amyloid-like proteinopathies, or as inhibitors of self-association of proteins, or they can self-assemble on biopolymers as on templates. In this study, human insulin protein was used to analyze nanoparticle-induced proteinopathy in physiological conditions. It is known that human insulin may form amyloid fibers, but only under extreme experimental conditions (very low pH and high temperatures). Here, we have shown that the quantum dots (QDs) may induce amyloid-like fibrillation of human insulin under physiological conditions through a complex process strongly dependent on the size and surface charge of QDs. The insulin molecular structure and fibril morphology have been shown to be modified at different stages of its fibrillation, which has been proved by comparative analysis of the data obtained using circular dichroism, dynamic light scattering, amyloid-specific thioflavin T (ThT) assay, transmission electron microscopy, and high-speed atomic force microscopy. We have found important roles of the QD size and surface charge in the destabilization of the insulin structure and the subsequent fibrillation. Remodeling of the insulin secondary structure accompanied by remarkable increase in the rate of formation of amyloid-like fibrils under physiologically normal conditions was observed when the protein was incubated with QDs of exact specific diameter coated with slightly negative specific polyethylene glycol (PEG) derivatives. Strongly negatively or slightly positively charged PEG-modified QDs of the same specific diameter or QDs of bigger or smaller diameters had no effect on insulin fibrillation. The observed effects pave the way to the control of amyloidosis proteinopathy by varying the nanoparticle size and surface charge.

Project description:Multi environment testing helps identify stable genotypes especially for adverse abiotic stress situations. In the era of climate change and multiple abiotic stresses, it becomes important to analyze stability of rice lines under both irrigated and stress conditions. Mutants are an important genetic resource which can help in revealing the basis of natural variation. We analyzed 300 EMS induced mutants of aus rice cultivar Nagina22 (N22) for their G?×?E interaction and stability under low phosphorus (P), water limited and irrigated conditions. Environmental effect and interaction were more significant than genotypic contribution on grain yield (GY), productive tillers (TN) and plant height (PH) under these three environmental conditions in dry season, 2010. GY and TN were more affected by low P stress than by water limited condition, but PH was not significantly different under these two stresses. Mutants G17, G209, G29, G91, G63 and G32 were stable for GY in decreasing order of stability across the three environments but G254 and G50 were stable only in low P, G17 and G45 only in water limited and G295 and G289 only in normal irrigated condition. We then selected and evaluated 3 high yielding mutants, 3 low yielding mutants and N22 for their stability and adaptability to these 3 environments in both wet and dry seasons for six years (2010-2015). The most stable lines based on the combined analysis of 12 seasons were G125 (NH210) under normal condition, G17 (NH686), G176 (NH363) and G284 (NH162) in low P condition and G176 (NH363) under water limited condition. G176 was the best considering all 3 conditions. When screened for 15 Pup1 gene-specific markers, G176 showed alleles similar to N22. While two other low-P tolerant lines G17 and G65 showed N22 similar alleles only at k-1 and k-5 but a different allele or null allele at 13 other loci. These stable mutants are a valuable resource for varietal development and to discover genes for tolerance to multiple abiotic stresses.

Dataset Information

Amyloid fibrillation of insulin under water-limited conditions.

Publications

Amyloid fibrillation of insulin under water-limited conditions.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets