Polycystin-2 (PC2), a calcium-activated cation TRP channel, is involved in diverse Ca signaling pathways. Malfunctioning Ca regulation in PC2 causes autosomal-dominant polycystic kidney disease. Here we report two cryo-EM structures of distinct channel states of full-length human PC2 in complex with lipids and cations. The structures reveal conformational differences in the selectivity filter and in the large exoplasmic domain (TOP domain), which displays differing N-glycosylation. The more open structure has one cation bound below the selectivity filter (single-ion mode, PC2), whereas multiple cations are bound along the translocation pathway in the second structure (multi-ion mode, PC2). Ca binding at the entrance of the selectivity filter suggests Ca blockage in PC2, and we observed density for the Ca-sensing C-terminal EF hand in the unblocked PC2 state. The states show altered interactions of lipids with the pore loop and TOP domain, thus reflecting the functional diversity of PC2 at different locations, owing to different membrane compositions.
Strong solvent signals lead to a disappearance of weak protein signals close to the solvent resonance frequency and to base plane variations all over the spectrum. AUREMOL-SSA provides an automated approach for solvent artifact removal from multidimensional NMR protein spectra. Its core algorithm is based on singular spectrum analysis (SSA) in the time domain and is combined with an automated base plane correction in the frequency domain. The performance of the method has been tested on synthetic and experimental spectra including twodimensional NOESY and TOCSY spectra and a threedimensional 1 H, 13 C-HCCH-TOCSY spectrum. It can also be applied to frequency domain spectra since an optional inverse Fourier transformation is included in the algorithm.
Diatoms are eukaryotic unicellular algae characterized by silica cell walls and associated with three unique protein families, the pleuralins, frustulins, and silaffins. The NMR structure of the PSCD4 domain of pleuralin-1 from Cylindrotheca fusiformis contains only three short helical elements and is stabilized by five unique disulfide bridges. PSCD4 contains two binding sites for Ca(2+) ions with millimolar affinity. NMR-based interaction studies show an interaction of the domain with native silaffin-1A as well as with α-frustulins. The interaction sites of the two proteins mapped on the PSCD4 structure are contiguous and show only a small overlap. A plausible functional role of pleuralin could be to bind simultaneously silaffin-1A located inside the cell wall and α-frustulin coating the cell wall, thus connecting the interfaces between hypotheca and epitheca at the girdle bands. Restrained molecular dynamics calculations suggest a bead-chain-like structure of the central part of pleuralin-1.
In the last 20 years the demand for peacekeeping operations has significantly increased, and today there are close to 1 million peacekeepers worldwide. The aim of this qualitative study was to extend past research on peacekeeping by investigating the psychological experiences of Italian peacekeepers during their missions in war contexts. Thirty male peacekeepers aged 28 -41 were recruited and interviewed. A thematic analysis was carried out and involved line-by-line coding with codes deriving from narratives. Five major themes emerged: the motivations to participate in an operation; the group as a buffer against combat-related stress; the hardest aspects of the experience; coping strategies toward the mission, perceived as a life-or-death experience; and benefits and negative consequences after going back home. The relevance of these issues is discussed. Findings can help in developing training and support programs tailored at operational demands that are distinctive for this kind of high-stress occupation.
Public Significance StatementThe in-depth examination of interviews employed in this study has enabled an exploration of male peacekeepers' experiences and the data from this study may provide useful considerations for professionals working in the field of peacekeeping. These insights can be used to develop training and support programs tailored at operational demands that are distinctive for high-stress occupations.
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