Fig. 5: Shared primase-binding peptide in archaeal PolD and eukaryotic Polα.

a Specific binding of immobilized-DP2(1196–1270) to primase measured by biolayer interferometry (BLI). Steady-state analysis was performed using the average signal measured at the end of the association step (between 290 and 300 s). b Comparative binding of immobilized-DP2(1196–1270) and -DP2(1196–1253) to primase measured by BLI. c Specific binding of immobilized primase with increasing concentrations of cPIP by surface plasmon resonance (RU: resonance units). Steady-state analysis was performed using the average signal measured at the end of the association step. The range of concentrations used in the binding experiments are listed in the Methods section. d Structural comparison of the P. abyssi PolD DP1-DP2(1093–1216) region of the cryo-EM structure with the Homo sapiens Polα POLA2-POLA1(1319–1456) crystal structure (PDB ID: 5EXR). e Shared structural features between archaeal PolD and eukaryotic Polα C-terminal regions. Conserved α-helices and Zn-binding domain are shown in blue and green, respectively. f The cPIP of DP2 resembles the primase-interacting motif located in the C terminus of Polα. Top panel: multiple-sequence alignment highlighting the conservation between the PolD cPIP motifs from Thermococcus species and the primase-interacting peptides of Polα. Sequence similarities are highlighted with light purple boxes, whereas conserved residues are shown with dark purple boxes. Bottom panel: superimposition of the X-ray crystal structures of the cPIP from P. abyssi and the primase-interacting peptide of H. sapiens Polα (PDB ID: 5EXR). Cα-traces are represented as ball and sticks. Conserved residues are highlighted using larger spheres. Source data are provided as a Source Data file.