Fig. 5
From: Direct binding of CEP85 to STIL ensures robust PLK4 activation and efficient centriole assembly
STIL NTD interacts with CEP85 cc4 through a conserved interface. a High-resolution structure of Trichoplax adhaerens STIL NTD. Left, as ribbon presentation, rainbow coloured from N- to C-terminus. α-helices (α), β-sheets (β) and loops (L) are labelled consecutively. Right, equivalent view as molecular surface coloured by CONSURF evolutionary conservation score (right) from unconserved (cyan) to highly conserved (burgundy), revealing the presence of two conserved patches on the surface of Trichoplax adhaerens STIL NTD. Ringed in blue are residues L47 and R50 (L64 and R67 in human STIL) that are part of patch 1 and are located at the interaction interface in the CEP85-STIL complex as shown in c. b High-resolution structure of human CEP85 cc4 as ribbon presentation (rainbow coloured from N- to C-terminus) (left) and as molecular surface coloured by CONSURF evolutionary conservation score (right). The dashed box indicates the CEP85 cc4 region with visible electron density in the CEP85-STIL complex (shown in c). Residues Q640 and E644 that are found at the interface of this complex are ringed in blue. c Complex of Trichoplax adhaerens STIL NTD and human CEP85 cc4 at a resolution of 4.6 Å, as a ribbon presentation. The correct register of the CEP85 cc4 was obtained by introducing methionines into CEP85 cc4 and calculating phased anomalous difference maps from corresponding selenomethionine-derivate data sets (Supplementary Fig. 4b). The human equivalents of the Trichoplax adhaerens STIL residues are indicated in brackets. d Mutation of conserved interface residues in STIL NTD and CEP85 cc4 compromises binding affinity. ITC measurements of chicken STIL NTD titrated into human CEP85 cc4 at 25 °C. Excess heat observed for the mutant proteins approach that obtained when titrating wild-type (WT) STIL NTD into buffer alone as a non-binding control. Conserved residues mutated in chicken STIL NTD are L60A and R63A, equivalent to L64 and R67A in human STIL (in brackets) and L47 and R50 in Trichoplax adhaerens (Fig. 5a)
