Figure 2. A peptide derived from EBOV polymerase co-factor VP35 (NPBP) binds ΔNP_NTD with high affinity and specificity, related to Figure S1D, S2, S3, S4 and Table S1.

(A) Domain organization of EBOV VP35, including an oligomerization and IID domains. There is a highly conserved region N-terminal to the oligomerization domain, termed NPBP. (B) Impact of the VP35 N-terminus was evaluated by the Ebola minigenome assay. Ability of either wildtype or mutant VP35 proteins lacking various N-terminal sequences were tested and plotted as normalized minigenome activity, where wildtype VP35 activity was set to 100%. Below representative western blots show similar levels of VP35 protein expression. β-tubulin was used as loading control. (C) Summary of binding measurements by ITC between ΔNP_NTD and VP35 N-terminal truncation mutants reveal that residues 20–48 are necessary and sufficient for high affinity binding. n.d., not determined. (D) The structure of the dual-octameric ring of ΔNP_NTD in complex with VP35 NPBP peptide in a ribbon representation (left) and in a 90° rotated configuration (right). Each NPBP/ΔNP_NTD complex in the asymmetric unit is colored yellow/orange (mol A/mol E), magenta/blue (mol B/mol F), green/purple (mol C/mol G), and cyan/pink (mol D/mol H).