Cox M M, Soltis D A, Lehman I R, DeBrosse C, Benkovic S J
J Biol Chem. 1983 Feb 25;258(4):2586-92.
The complete exchange of strands between circular single-stranded and full length linear duplex DNAs promoted by the recA protein of Escherichia coli is dependent upon the hydrolysis of ATP and is strongly stimulated by the single-stranded DNA binding protein (SSB). In the presence of SSB, stable complexes of recA protein and single-stranded DNA are formed as an early step in the reaction. These complexes dissociate when the ADP/ATP ratio approaches a value of 0.6-1.5, depending upon reaction conditions. Thus, ATP hydrolysis never proceeds to completion but stops when 40-60% of the input ATP has undergone hydrolysis. recA protein can participate in a second round of strand exchange upon regeneration of the ATP. While 100-200 mol of ATP are hydrolyzed/mol of heteroduplex base pair formed under standard reaction conditions in the presence of SSB, this value is reduced to 16 at levels of ADP lower than that required to dissociate the complexes. ATP hydrolysis appears to be completely irreversible since efforts to detect exchange reactions using 18O probes have been unsuccessful.
由大肠杆菌的recA蛋白促进的环状单链DNA与全长线性双链DNA之间的链完全交换依赖于ATP的水解，并受到单链DNA结合蛋白（SSB）的强烈刺激。在存在SSB的情况下，recA蛋白与单链DNA形成稳定复合物是反应的早期步骤。根据反应条件，当ADP/ATP比值接近0.6 - 1.5时，这些复合物会解离。因此，ATP水解不会进行到底，而是在40 - 60%的输入ATP发生水解时停止。ATP再生后，recA蛋白可以参与第二轮链交换。在标准反应条件下，存在SSB时，每形成1摩尔异源双链碱基对会水解100 - 200摩尔ATP，但在低于复合物解离所需的ADP水平时，该值降至16。由于使用18O探针检测交换反应未成功，ATP水解似乎是完全不可逆的。
