Dynamics and conformational change of UPF2L upon RNA binding. (A) Negative-stain EM 2D class averages of UPF2L alone. (B) Negative-stain EM 2D class averages of UPF2L incubated with a fourfold molar excess hp-RNA, leading to more V/U shaped particles. (C) Negative-stain EM 2D class averages of UPF2L with a fourfold molar excess of ss-RNA, leading to more defined, compact particles. (A–C) Scale bar, 10 nm. (Right) Plot showing the percentage of particles classifying into elongated versus compact, U/V-shaped 2D classes. (D) Relaxed AlphaFold2 models of UPF2L (without RNA) showing highly dynamic regions between the individual MIF4G domains and the UPF1-binding domain ([orange] D1, [brown] D2, [green] D3, [magenta] U1BD), agreeing with conformational dynamics and mostly elongated particles observed in A and B.
