Fig. 5: Comparison of cargo-bound Msn5 with XPO5 and XPO1.
From: Phosphate-dependent nuclear export via a non-classical NES class recognized by exportin Msn5
a Alignment of RanGTP in the Ran/cargo-bound structures Msn5 (grey) and XPO5 (pink; 3A6P [[https://doi.org/10.2210/pdb3A6P/pdb]). RanGTP is omitted for clear view of the cargoes, which are drawn as spheres - pPho4 in wheat and pre-miRNA in green. HEAT repeats that contact the cargoes are labeled with their numbers. b Cargo-bound Msn5 and XPO5 shown in a are structurally aligned using DALI and the conservation of Msn5 residues that contact pPho4 are shown on the pPho41-200-bound Msn5 surface. Bound pPho4 is shown as transparent cartoon and sticks. Msn5 residues that contact pPho4 are colored dark pink if identical with the corresponding XPO5 residue, light pink if similar and dark teal if not conserved. c Top: XPO1 (yellow)-RanGTP (teal)-SNUPN (red) (3GJX [https://doi.org/10.2210/pdb3GJX/pdb]) oriented as in (a). Bottom: View of the SNUPN cNES in the NES binding groove of XPO1 (viewing in the direction of arrow in the top panel). d Cartoon summarizing Msn5-Pho4 NES (left) vs. XPO1-cNES (right) recognition. The Pho4 NES is an extended 35-amino acids-long chain with two phospho-serines spaced 14 residues (30 Å) apart and many small hydrophobic and polar residues. It is depleted of basic side chains as it interacts with the highly basic and flexible concave surface of Msn5. In contrast, the cNES is short (8–15 residues long), with 4–5 hydrophobic side chains that bind in a hydrophobic groove located on the convex surface of XPO1. The groove holds the same conformation as it binds structurally variable cNESs (dashed lines depict variability, solid line shows the structurally conserved single turn of helix).
