Fig 1.
Rotavirus virion, viroplasms, and one hypothetical model of the replicase–assembly pathway.
(A) Structure of the triple-layered rotavirus virion [1]. Locations of viral proteins are indicated. VP1 and VP3 are modeled into the structure. (B) Confocal micrograph of a rotavirus-infected monkey kidney cell. The cell was stained to show the locations of VP2 (red), NSP2 (green), and the nucleus (blue). A single viroplasm (V) is outlined with a white circle. (C). Electron micrograph of resin-embedded, negatively-stained cell section. A single, electron-dense viroplasm (V) is shown in the center. (D) Electron micrographs of biochemically purified assembly intermediates and one hypothetical model of early rotavirus assembly. Beneath each micrograph is a cartoon representation (or, in the case of the DLP, a structure) that depicts the possible composition of the assembly intermediate, and the images are ordered according to one hypothetical pathway of early virion morphogenesis. The protein composition and activity of each particle type has not been experimentally validated.
Fig 2.
Rotavirus VP1-VP2 interactions.
(A) Left: Structure of the rotavirus VP2 core shell in the context of a DLP [5]. VP2-A and VP2-B monomers of one decamer unit are colored blue and cyan, respectively. Right: The core shell is shown computationally sliced through the middle to reveal the likely locations of VP1–VP3 heterodimers. (B) VP1–VP2 contacts in the fully-assembled DLP [17]. VP2-A, VP2-B, and VP1 are shown in ribbon representation and colored blue, cyan, and pink, respectively. The visible regions of the VP2 N termini are colored red. (C) VP1 is shown in surface representation and computationally sliced through the middle to reveal four tunnels [19]. The location of the retracted priming loop is shown in yellow, and a 7-nucleotide +RNA template that is bound out-of-register with the active site is shown in black. VP2 is predicted to engage VP1 at the +RNA exit interface and trigger structural rearrangements including a repositioning of the priming loop and +RNA template.