Extended Data Fig. 5: Electron microscopy of in vitro-reconstituted M1 helical tubes.
From: The native structure of the assembled matrix protein 1 of influenza A virus
a, Negative-stain image of aggregated M1 tubes found within the pellet after sucrose cushion centrifugation. b, Negative-stain image of an in vitro-assembled M1 tube in the presence of nucleic acid. Images in a, b are representative of at least five independent preparations. c, A typical cryo-EM image of in vitro assembled M1 tubes at 2.7 μm underfocus, representative of three independent preparations. d, Selected class averages with tube diameter between 327–329 Å as determined by segclassexam. The lower left class average has minimal out-of-plane tilt and was used to test possible helical parameters by segclassreconstruct. e, Cryo-EM density of an M1 monomer is shown, the surface is coloured by local resolution of the map as determined by RELION. Boxes indicate regions magnified in g–i. f, Global FSC curve of the final in vitro-assembled M1 tube helical reconstruction (Fig. 2d). g–i, Magnified regions of cryo-EM density as indicated in e and their fitted molecular models.
