Figure 5.

Facilitated exchange of RPA^f on ssDNA by RPA and SSB. (A) Schematic of stopped-flow experiments to capture facilitated exchange of RPA^f by unlabeled RPA^WT. (B) Pre-formed RPA^f-ssDNA complexes formed on (dT)₉₇ ssDNA substrates are effectively displaced by unlabeled RPA^WT. The rate of exchange increases with concentration of unlabeled RPA^WT, and (C) yields an apparent observed rate of 0.7 ± 0.1 × 10⁻¹² M⁻¹ s⁻¹ for facilitated exchange. (D) Schematic of facilitated exchange experiments with E. coli SSB, which (E) displaces or exchanges with RPA^f more effectively than RPA^WT with (F) an apparent observed rate of 47.3 ± 1.7 × 10⁻¹² M⁻¹ s⁻¹.