The pull-down assay of the ssDNA-bound proteins. (A) The indicated concentrations of the proteins were incubated with ssDNA-immobilized streptavidine sepharose. After three washes, ssDNA-bound proteins were analyzed by SDS-PAGE. The asterisk indicates the band derived from the streptavidine sepharose. A band corresponding to BSA was observed in all lanes because it was present in the washing buffer. (B) Effect of pH on the ssDNA-binding properties of SSB and RecO. The buffers contained 50 mM MES-NaOH (pH 6.5, lanes 1–6), 50 mM Tris-HCl (pH 7.5, lanes 7–12) or 50 mM Tris-HCl (pH 8.5, lanes 13–18), together with 1 mM DTT, 0.15% Tween20 and 0.2 mg/ml BSA. The pull-down assays were performed as described in Figure 7. (C) The pull-down assay was performed in buffer containing 50 mM Tris-HCl (pH 8.5), 1 mM DTT, 0.15% Tween20 and 0.2 mg/ml BSA.