Fig. 1: Structures of ribosomal complexes inhibited by SARS-CoV-2 Nsp1 solved by cryo-EM.
From: SARS-CoV-2 Nsp1 binds the ribosomal mRNA channel to inhibit translation
a, Views of Nsp1 (red) binding to a 43S PIC containing the core of initiation factor eIF3 (cyan), eIF1 (blue) and the eIF2–tRNA ternary complex (magenta). b, Overview of Nsp1 (red) binding to a translationally inactive 80S complex. c, Sucrose gradient fractionation of HEK lysate supplemented with Nsp1. Nsp1 co-migrates with 40S and 80S ribosomal particles in a 15–45% (wt/vol) sucrose gradient. His6-tagged Nsp1 is visualized by western blot using an α-His antibody (fractions 1–20 and loading control (c), with 0.2 μg of purified His6-Nsp1 applied), while the rRNA content in corresponding fractions is monitored on an agarose gel. All samples for the western blot are derived from the same experiment and the blots were processed in parallel. d, In the in vitro binding assay, wild-type (WT) Nsp1 was added to 40S and 60S ribosomal subunits and loaded on a 30% (wt/vol) sucrose cushion. Unbound proteins remained in the supernatant (SN), while bound Nsp1 co-pelleted with 40S (P). e, Overview of Nsp1 binding to the small ribosomal subunit. Nsp1 (red) binds close to the mRNA entry site and contacts uS3 (blue) from the ribosomal 40S head as well as uS5 (green), the C terminus of eS30 (orange) and h18 of the 18S rRNA (gray) of the 40S body. A magnified view of the Nsp1 binding area is shown in the box. Uncropped gel images for c and d are available online as source data.
