West S C, Cassuto E, Howard-Flanders P
Mol Gen Genet. 1982;186(3):333-8. doi: 10.1007/BF00729451.
The RecA protein of Escherichia coli is essential for genetic recombination and postreplicational repair of DNA. In vitro, RecA protein promotes strand transfer reactions between full length linear duplex and single stranded circular DNA of phi X174 to form heteroduplex replicative form II-like structures (Cox and Lehman 1981 a0. In a similar way, it transfers one strand of a short duplex restriction fragment to a single stranded circle. Both reactions require RecA and single strand binding protein (SSB) in amounts sufficient to saturate the ssDNA. The rate and extent of strand transfer is enhanced considerably when SSB is added after preincubation of the DNA with RecA protein. In contrast, SSB protein is not required for RecA protein catalysed reciprocal strand exchanges between regions of duplex DNA. These results indicate that while SSB is necessary for efficient transfer between linear duplex and ssDNA to form a single heteroduplex, it is not required for branch migration reactions between duplex molecules that form two heteroduplexes.
大肠杆菌的RecA蛋白对于DNA的遗传重组和复制后修复至关重要。在体外，RecA蛋白促进全长线性双链体与φX174单链环状DNA之间的链转移反应，以形成异源双链复制形式II样结构（考克斯和莱曼，1981年a0）。以类似的方式，它将短双链限制片段的一条链转移到单链环上。这两种反应都需要RecA和单链结合蛋白（SSB），其用量足以使单链DNA饱和。当在DNA与RecA蛋白预孵育后加入SSB时，链转移的速率和程度会显著提高。相比之下，RecA蛋白催化双链DNA区域之间的相互链交换不需要SSB蛋白。这些结果表明，虽然SSB对于线性双链体和单链DNA之间有效转移以形成单个异源双链是必需的，但对于形成两个异源双链的双链分子之间的分支迁移反应则不是必需的。
