Movie 1. Cryoem Structure of Ad35f at 6 Å Resolution

MOVIE LEGENDS

Movie 1. CryoEM structure of Ad35F at 6 Å resolution.

Part1 of the movie shows the structure of the virion rotating 180° about a 2-fold symmetry axis. The density is radially color-coded.

Part 2 of the movie shows a rotating view of the penton base/fiber complex at one vertex with the density radially color-coded.

Part 3 of the movie displays the penton base density in the reconstruction as white and the 1X9T crystal structure fit within the density as a rainbow colored ribbon. The ribbon is colored with the N-terminus in blue and the C-terminus in red. The isosurface level changes to reveal just the strongest density including the α-helical rods, then the thickness of the displayed density slab is changed to reveal just the outermost part of the penton base, followed by a slab centered around the gold α-helix (aa 482-491), and ending with a slab centered around the cyan α-helix (aa 176-193).

Movie 2. Density in the difference map assigned to proteins IX, VI and IIIa.

Part 1 of the movie begins with the density in approximately one icosahedral facet on the outer surface of the capsid, which includes four trimeric regions and three helical bundles. Each trimeric region is assigned to three monomers of the N-terminal virus interaction domain of protein IX. Each helical bundle is assigned to four monomers of the C-terminal domain of protein IX, which is predicted to have a strong propensity for coiled coil formation. Enlarged views are shown of a trimeric region followed by an enlarged view of a helical bundle.

Part 2 shows a helical bundle rotating together with a model for a 40 residue long tetrameric coiled coil (red ribbon). The isosurface level changes during the second rotation to reveal the weak fourth α-helical rod in the cryoEM density.

Part 3 illustrates the weak connections observed at low isosurface values between the trimeric regions and the helical bundles. The weak connections are assigned to the alanine-rich low complexity region in the middle of the protein IX sequence.

Part 4 of the movie begins with the density in approximately one icosahedral facet, which includes small disks of density. The crystal structure for one hexon, a hexon in position 3 of the asymmetric unit, is displayed as a blue ribbon with the loop implicated in binding to protein VI shown in magenta (aa 770-787). The sidechains of several hydrophobic residues (L463, L467, W468 and F471) at the top of the hexon cavity are shown in yellow. The view is changed from a top view to a side view, ending with the hexon towers at the top of the image and the hexon cavity facing the interior of the virus at the bottom of the image. The thickness of the displayed density slab is changed to show just a slab through the middle of the hexon. This slab displays one of three density prongs protruding into the hexon cavity. Note that the prong comes within 10Å of the hexon loop implicated in protein VI binding (magenta). Both the disk at the top of the hexon cavity and the prongs at the bottom of the hexon cavity are tentatively assigned to protein VI.

Part 5 shows the cluster of α-helical density on the inner capsid surface assigned to the N-terminal region (aa 1-400) of one protein IIIa monomer. The cryoEM density is displayed as transparent white. Thirteen α-helices, ranging in length from 12 to 23 residues, are shown as helical ribbons (magenta) modeled within the cryoEM density. The view is rotated 360°.