Figure 3. Basis for CBF3−CEN3 recognition.

(a) Overview of the dimeric CBF3−CEN3 complex. (b) and (c) Two views of the Ndc10^DBD-DNA interface. DNA induces dimerization of Ndc10^DBD. (d) Details of Ndc10^DBD−DNA contacts. Residues in contact with DNA are shown as green spheres. Cartoon representation of only one Ndc10 subunit is shown. (e) EM density map of the CBF3−CEN3-biotin avidin complex orients and positions the DNA duplex. (f) Overview of Cep3B-Ctf13 contacts with DNA in CBF3^A. (g) Details of Cep3A−Ctf13−CDEIII interface, showing Zn₂Cys₆ cluster contacting the CCG motif and αMN helix contacting the TGT motif. Ctf13 contacts the minor groove midway between the CCG and TGT motifs. (h) Schematic of CBF3-DNA interactions. Sequence of the nuclease resistant 56 bp segment protected by CBF3 is shown ¹⁷. Arrow, diamond and circle symbols as in Fig. 1i. Colored horizontal lines indicate contacts to CBF3 subunits. (i) and (j) EM density of the Zn₂Cys₆ clusters interacting with CEN3-DNA for (i) Cep3A of CBF3^A and (j) Cep3A of CBF3^B.