Fig. 3: Mechanically soft leading proteins increase nuclear import.
From: Structural anisotropy results in mechano-directional transport of proteins across nuclear pores
a–c, Nuclear import kinetics of R16-(V13P/WT/Y9P) compared to their Ig27 respective monomer variant: representative confocal images of U2OS cells after 30 min into the recovery phase (scale bar, 10 µm) (a); average time courses of the relative nucleus-to-cytoplasm localization of each protein construct (b); related import rates for V13P (kI = 1.80 ± 0.09 ks−1, n = 161), R16-V13P (kI = 1.64 ± 0.04 ks−1, n = 276); WT (kI = 1.62 ± 0.05 ks−1, n = 249), R16-WT (kI = 1.42 ± 0.04 ks−1, n = 192); Y9P (kI = 1.09 ± 0.03 ks−1, n = 279), R16-Y9P (kI = 1.58 ± 0.07 ks−1, n = 80) (c). Significance levels for two-tailed Mann–Whitney non-parametric test: NS, P > 0.05; **P < 0.001; ****P < 0.0001. V13P versus R16-V13P, P = 0.10; WT versus R16-WT, P = 3.84 × 10−3; Y9P versus R16-Y9P, P = 3.70 × 10−10. d, Relative acceleration resulting from the addition of an N-terminal R16 domain as a function of the difference in mechanical stability between R16 and the Ig27 variant (V13P, WT or Y9P). e, Import kinetics of the V13P, WT and Y9P monomers (55 kDa) versus the construct with an N-terminal R16 domain (70 kDa). In all cases, the import kinetics are brought up to the rate set by their respective mass law. In the case of mechanically stiff proteins (Y9P), this results in a net acceleration of the import kinetics relative to the monomer alone. f, Schematics of the dynamics of nuclear translocation of a Y9P monomer (left) versus the R16-Y9P construct (right). Adding the soft R16 domain next to the NLS accelerates the nuclear passage of mechanically stiff cargos, despite increasing their mass. All points and bar plots indicate mean ± s.e.m.
