C-Terminal Domain Swapping of SSB Changes the Size of the ssDNA Binding Site
Binding of KpSSB to dT20–60. KpSSB (0, 19, 37, 77, 155, 310, 630, 1250, 2500, and 5000 nM) was incubated for 30 min at 25°C with 1.7 nM of (a) dT20, (b) dT25, (c) dT35, (d) dT45, (e) dT50, (f) dT55, or (g) dT60 in a total volume of 10 μL in 20 mM Tris-HCl pH 8.0 and 100 mM NaCl. Aliquots (5 μL) were removed from each reaction solution and added to 2 μL of gel-loading solution (0.25% bromophenol blue and 40% sucrose). The resulting samples were resolved on a native 8% polyacrylamide gel at 4°C in TBE buffer (89 mM Tris borate and 1 mM EDTA) for 1 h at 100 V and visualized by autoradiography. Complexed and free DNA bands were scanned and quantified.