SPR analysis.

Protein—protein interactions within (A) PriA—DnaD, (B) PriA—DnaD1-204, (C) PriA—DnaD1-200, (D) PriA—DnaD1-195, (E) DnaA—DnaD and (F) DnaA—DnaD1-195 were analyzed using SPR. SaPriA and SaDnaA were individually immobilized on Series S sensor chips CM5, and the binding experiments were carried out using a Biacore T200 (GE Healthcare Bio-Sciences, Piscataway, NJ, USA). Control samples were used to monitor the sensor chip surface stability, demonstrating reproducibility throughout the duration of the experiments. The estimated K_d values were derived by fitting the association and dissociation signals with a 1:1 (Langmuir) model using the Biacore T200 Evaluation Software. The residual plots for SPR fitting were shown in S3 Fig.