Figure 5. Effects of ssDNA overhangs on the formation of RecA nucleoprotein filaments.

(A) Time traces of the extension of one end-closed 595 bp DNA with a 12 nt 5’ ssDNA tail in 1 µM RecA, 1 mM ATP, 1x ATP regeneration system, 50 mM KCl, 10 mM MgCl₂, pHpH 7.4, at 37°C. A stable RecA nucleoprotein filament was formed after a spontaneous RecA polymerization at around 5 pN. (B) Time traces of a DNA with the same structure as the DNA in (A) at 24°C (other conditions remained unchanged). A stable RecA nucleoprotein filament was also observed for over 5000 second, after a spontaneous RecA polymerization at around 3 pN. The shadowed area represents the process of solution flow with RecA.