Figure 3

The gp43 DNA polymerase from bacteriophage RB69 has been solved in complex with a DNA primer/template. The gp45 clamp from RB69 has been solved in complex with a synthetic peptide containing the PIP box motif. A.) The RB69 gp43 polymerase in complex with DNA is docked to the RB69 gp45 clamp with the duplex DNA aligned with the central opening of gp45 (gray). The N-terminal domain (tan), the 3' - 5' editing exonuclease (salmon), the palm domain (pink), the fingers domain (light blue), and thumb domain (green comprise the DNA polymerase. The C-terminal residues extending from the thumb domain contain the PCNA interacting protein box motif (PIP box) shown docked to the 45 clamp. B.) The active site of the gp43 polymerase displays the template base to the active site with the incoming dNTP base paired and aligned for polymerization. C.) The C-terminal PIP box peptide (green) is bound to a subunit of the RB69 gp45 clamp (gray).