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The aggregation of amyloidogenic proteins is often related to the occurrence of neurodegenerative diseases, including fused in sarcoma protein (FUS) in frontotemporal lobar degeneration and amyotrophic lateral sclerosis diseases. Recently, the SERF protein family has been reported to have a significant regulatory effect on amyloid formation, but it is still unclear about the detailed mechanisms of SERF acting on different amyloidogenic proteins. Herein, nuclear magnetic resonance (NMR) spectroscopy and fluorescence spectroscopy were used to explore interactions of ScSERF with three amyloidogenic proteins FUS‐LC, FUS‐Core, and α‐Synuclein. NMR chemical shift perturbations reveal them sharing similar interaction sites on the N‐terminal region of ScSERF. However, the amyloid formation of α‐Synuclein protein is accelerated by ScSERF, while ScSERF inhibits fibrosis of FUS‐Core and FUS‐LC proteins. Both the primary nucleation and the total amount of fibrils produced are detained. Our results suggest a diverse role of ScSERF in regulating the fibril growth of amyloidogenic proteins. [ABSTRACT FROM AUTHOR]

In‐cell NMR spectroscopy is an effective tool for observing proteins at atomic resolution in their native cellular environment. However, its utility is limited by its low sensitivity and the extensive line broadening caused by nonspecific interactions in the cells, which is even more pronounced in human cells due to the difficulty of overexpressing or delivering high concentrations of isotopically labeled proteins. Here, we present a high‐sensitivity tag (wPSP‐6F) containing two trifluoromethyl groups that can efficiently label globular proteins with molecular weights in the 6–40 kDa range under mild conditions. This tag allowed us to detect globular proteins in human cells at concentrations as low as 1.0 μM, which would not have been achievable with 15N or 3‐fluorotyrosine labeling. Moreover, we detected conformational changes and interactions of proteins in the cellular environment. The new sensitive 19F NMR tag may significantly expand the scope of protein NMR in human cells. [ABSTRACT FROM AUTHOR]

We used Xenopus laevis oocytes, a paradigm for a variety of biological studies, as a eukaryotic model system for in-cell protein NMR spectroscopy. The small globular protein GB1 was one of the first studied in Xenopus oocytes, but there have been few reports since then of high-resolution spectra in oocytes. The scarcity of data is at least partly due to the lack of good labeling strategies and the paucity of information on resonance broadening mechanisms. Here, we systematically evaluate isotope enrichment and labeling methods in oocytes injected with five different proteins with molecular masses of 6 to 54 kDa. 19F labeling is more promising than 15N, 13C, and 2H enrichment. We also used 19F NMR spectroscopy to quantify the contribution of viscosity, weak interactions, and sample inhomogeneity to resonance broadening in cells. We found that the viscosity in oocytes is only about 1.2 times that of water, and that inhomogeneous broadening is a major factor in determining line width in these cells. [ABSTRACT FROM AUTHOR]

Conformational change of cytochrome c (cyt c) caused by interaction with cardiolipin (CL) is an important step during apoptosis, but the underlying mechanism is controversial. To comprehensively clarify the structural transformations of cyt c upon interaction with CL and avoid the unpredictable alias that might come from protein labeling or mutations, the conformation of purified yeast iso–1 cyt c with natural isotopic abundance in different contents of CL was measured by using NMR spectroscopy, in which the trimethylated group of the protein was used as a natural probe. The data demonstrate that cyt c has two partially unfolded conformations when interacted with CL: one with Fe–His33 coordination and the other with a penta–coordination heme. The Fe–His33 coordination conformation can be converted into a penta–coordination heme conformation in high content of CL. The structure of cyt c becomes partially unfolded with more exposed heme upon interaction with CL, suggesting that cyt c prefers a high peroxidase activity state in the mitochondria, which, in turn, makes CL easy to be oxidized, and causes the release of cyt c into the cytoplasm as a trigger in apoptosis. [ABSTRACT FROM AUTHOR]

NMR Spectroscopy In their Communication on page 8686 ff., C. Li et al., demonstrate that 19F labeling is a good first choice for studying globular and disordered proteins in Xenopus oocytes, especially compared with conventional 15N ‐ or 13C ‐ methyl enrichment. By using 19F labeling, they found that, unlike E. coli cells, the viscosity in oocytes is only about 1.2 times that of water and that inhomogeneous broadening contributes 60 – 70 % to the line width. The labeling strategies and resonance broadening mechanisms in Xenopus oocytes were explored with the goal of expanding the application of this cell type. [ABSTRACT FROM AUTHOR]