The reaction solutions contained 5 µM circular φX ssDNA (ssDNA) or 15 µM linear φX dsDNA (dsDNA), 5 mM dATP, and 6 µM SpRecA, with or without 0.3 µM SpSsbB. The reactions were initiated by adding SpRecA at 0 min with no SpSsbB (■), by adding SpSsbB at 0 min and SpRecA at 10 min (♦), or by adding SpRecA at 0 min and SpSsbB at 10 min (▲). The reactions were carried out at 37 °C for the indicated times. SpRecA exhibited no dATP hydrolysis activity under these reaction conditions when DNA was omitted from the reaction solution (×).