Components and Architecture of the Rhabdovirus Ribonucleoprotein Complex

Abstract

Rhabdoviruses, as single-stranded, negative-sense RNA viruses within the order Mononegavirales, are characterised by bullet-shaped or bacteroid particles that contain a helical ribonucleoprotein complex (RNP). Here, we review the components of the RNP and its higher-order structural assembly.

Keywords: lagos bat virus; lyssavirus; rabies virus; rhabdoviruses; ribonucleoprotein structure; vesicular stomatitis virus; vesiculovirus.

Figure 1

Cryo-electron tomograms of rabies virus (RABV) and vesicular stomatitis virus (VSV) particles at the same scale. The locations of the M- and N-proteins are indicated by blue circles and purple rectangles, respectively. The location of the G-protein is indicated by red triangles, and the size of the L-protein, as derived from the electron density map of the VSV L-protein generated by [6], is indicated in green. The tomograms were acquired on an FEI Glacios (ThermoFisher, OR, USA) with a Falcon2 (ThermoFisher, OR, USA) direct electron detector, reconstructed in etomo [7] and visualised by employing 3dmod [7].

Figure 2

Comparison of the RABV and VSV N-protein structures (pdb 2gtt (RABV, [9]) and 2gic (VSV, [8])). (A) Comparison between the arrangement of the RABV N-protein in the crystal and docked in the cryo-electron density map from the top (i, view on the N-terminal domain) or the RNA binding groove (ii). Panels i and ii are not at the same scale. (B) Comparison of the residues interacting with the phosphate backbone (light green) of the viral genome between RABV and VSV. Positively charged residues that do not interact with the phosphate backbone but protrude into the RNA binding groove are depicted in dark green. (C) Comparison of the arrangement of N-proteins when docked into the CryoEM reconstructions of the RABV and VSV ribonucleoprotein complex (RNP). The N-monomers used for alignment of the different N-protein arrangements are connected using black arrows. EM: electron microscopy.

Figure 3

Comparison of the structure of the Lagos bat virus (LBV) (pdb 2w2s) and VSV (pdb 2w2r) M-proteins [3]. Residues involved in the interaction between the M-proteins are depicted in cyan on the N-terminal fragment and in light blue on the C-terminus.

Figure 4

Comparison of the electron density maps of the RNP of RABV (EMD-4995) and VSV (EMD-1663). The viewing direction is indicated above each panel, where: (A) a view from the side, (B) a view from the membrane and (C) a view towards the RNA binding groove. The distance between the helical turns, as well as the deviation of the helical turns from the central axis of the virion, are indicated. The location of the genome is indicated by a black dot or a black dotted line. The N-protein structures (pdb 2gtt (RABV), 2gic (VSV)) are docked in the corresponding densities and shown in purple. The VSV M-protein structures (2w2r, blue) are docked in the orientation, as proposed by [4], whilst the location, but not the orientation, of the RABV M-protein C-terminal domain is depicted as a blue density. The proposed location of the M-protein N-terminus is indicated by red stars. Dashed lines in the middle panel indicate the step to the corresponding M-protein on the next helical turn.