Pugh B F, Cox M M
J Biol Chem. 1987 Jan 25;262(3):1337-43.
Following DNA strand exchange, recA protein remains associated with the heteroduplex DNA product of the reaction. This association exists without significant changes (as measured by nuclease protection, topological state of the heteroduplex DNA, and rates of ATP hydrolysis) for at least 30 min after strand exchange is complete. The heteroduplex DNA is unwound as a result of this association to an extent at least as great as the unwinding observed when recA protein is bound to duplex DNA at pH 6.35. The extensive unwinding, in combination with the rates of ATP hydrolysis reported elsewhere, provide evidence that recA protein binding is contiguous throughout the heteroduplex DNA. This binding is disrupted upon challenge with heterologous single-stranded DNA, with rapid migration of recA protein to the challenging DNA. These results are discussed in relation to the mechanism of recA protein-promoted branch migration.
DNA链交换之后，RecA蛋白仍与反应产生的异源双链DNA产物结合。链交换完成后至少30分钟内，这种结合状态无显著变化（通过核酸酶保护、异源双链DNA的拓扑状态及ATP水解速率来衡量）。由于这种结合，异源双链DNA发生解旋，解旋程度至少与在pH 6.35条件下RecA蛋白与双链DNA结合时观察到的解旋程度相当。这种广泛的解旋，结合其他地方报道的ATP水解速率，证明RecA蛋白在整个异源双链DNA上的结合是连续的。用异源单链DNA进行挑战时，这种结合会被破坏，RecA蛋白会迅速迁移到被挑战的DNA上。本文结合RecA蛋白促进分支迁移的机制对这些结果进行了讨论。
