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Eric Martz
The first new influenza virus to emerge as an imminent pandemic threat in the 21st century is H1N1 swine flu. The drug oseltamivir (Tamiflu®) inhibits flu neuraminidase, a component necessary for virus spread, in susceptible flu strains. The development of oseltamivir was guided, in part, by crystallographically determined structures of flu neuraminidase, which is a homotetramer, shown with oseltamivir bound. Oseltamivir was designed to fit N2/N9 (neuraminidases from other strains of flu). Serendipitously, it also fits N1 by induced fit.

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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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Above is a transmembrane protein that takes up, into your intestinal cells, orally consumed peptide nutrients and drugs. Its lumen-face (shown above) opens and binds peptide or drug, then closes, while its cytoplasmic face (opposite end from the above) opens to release its cargo into the intestinal cell, which passes it on into the blood circulation.

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