Reconstructions of CpWT capsid and the complex with SRPK2ΔS1.

(A) Surface representations of the reconstructed SRPK2ΔS1/CpWT capsid complex (left) and apo-capsid (right). Kinases that decorated the 2-fold vertices of the capsid are colored in blue. Scale bar represents 10 nm. All views are along the icosahedral twofold axis. Both maps are low-pass filtered to 10 Å. (B) Central slice of the complex (left) shows a protruding density at the 2-fold vertex (indicated by blue arrowhead) and a stretch of density that extend to the presumably surface-bound kinase via the pore (indicated by the red arrowhead). The 2-fold, 3-fold and 5-fold symmetry axes are indicated by the grey dashed lines with oval, triangular and pentagonal symbols respectively in the central slice of apo-capsid (right). Scale bar represents 10 nm. (C) Segmentation and model fitting of the focus-refined SRPK2ΔS1/CpWT capsid at the 2-fold vertex. The capsid and SRPK2ΔS1 densities are colored in light grey and blue, respectively. Crystal structure of SRPK2 (PDB ID: 5MYV) was used in model fitting. Scale bar represents 5 nm. (D) Model fitting showed some densities of the reconstruction near the missing regions (a.a. 236–256, 507–511) between the spacer helices αS1 and αS2 of SRPK2ΔNS in the crystal structure. The missing regions are indicated by the red circle (upper panel); extra densities are observed near the N-terminal region of the kinase.