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A novel coronavirus was found to be the cause of a respiratory illness first detected in Wuhan, China in 2019. 3D structural studies are aiding scientists to understand how the coronavirus infects humans and helping to find new ways to treat the viral spread (video by Fusion Animation).

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Y Gu, V Srikanth, AI Salazar-Morales, R Jain, JP O'Brien, SM Yi, RK Soni, FA Samatey, SE Yalcin, NS Malvankar. Nature 2021 doi: 10.1038/s41586-021-03857-w
Geobacter pili were long thought to be electrically conductive protein nanowires composed of PilA-N. Nanowires are crucial to the energy metabolism of bacteria flourishing in oxygen-deprived environments. To everyone's surprise, in 2019, the long-studied nanowires were found to be linear polymers of multi-heme cytochromes, not pili. The first cryo-EM structure of pili (2021) reveals a filament made of dimers of PilA-N and PilA-C, shown. Electrical conductivity of pili is much lower than that of cytochrome nanowires. Evidence suggests that PilA-NC filaments are periplasmic pseudopili crucial for exporting cytochrome nanowires onto the cell surface, rather than the pili serving as nanowires themselves.

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Touching stretches cell membranes, opening mechanosensitive ion channels, leading to sensation by the nervous system. Pictured is the transmembrane region of a similar channel in bacteria. When closed, the narrow opening is lined by hydrophobic amino acid sidechains, making it non-conductive to ions.

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