Sekimizu K, Bramhill D, Kornberg A
Cell. 1987 Jul 17;50(2):259-65. doi: 10.1016/0092-8674(87)90221-2.
ATP is bound to dnaA protein with high affinity (KD = 0.03 microM) and hydrolyzed slowly to ADP in the presence of DNA. ADP is also bound tightly to dnaA protein and exchanges with ATP very slowly. The ATP form is active in replication; the ADP form is not. A unique conformation of oriC, formed in an early initiation stage, depends on dnaA protein being in the ATP form. The subsequent entry of dnaB protein to form a prepriming complex also requires ATP binding and is blocked by bound ADP. Inasmuch as hydrolysis of ATP is far slower than these initiation reactions and since the poorly hydrolyzable analogue ATP gamma S can replace ATP, the ATP function appears to be allosteric. The extraordinary affinity of ATP for dnaA protein, its slow hydrolysis to ADP, the profound inhibition of dnaA functions by ADP, and the very slow exchange of ADP all point to a possible regulatory role for these nucleotides in the cell cycle.
ATP以高亲和力（KD = 0.03微摩尔）与dnaA蛋白结合，并在DNA存在的情况下缓慢水解为ADP。ADP也紧密结合于dnaA蛋白，且与ATP的交换非常缓慢。ATP形式在复制中具有活性；ADP形式则无活性。在起始早期形成的oriC独特构象取决于处于ATP形式的dnaA蛋白。随后dnaB蛋白进入以形成预引发复合物也需要ATP结合，并被结合的ADP所阻断。由于ATP的水解远比这些起始反应慢，且由于难水解的类似物ATPγS可以替代ATP，ATP的功能似乎是变构的。ATP对dnaA蛋白的非凡亲和力、其缓慢水解为ADP、ADP对dnaA功能的深度抑制以及ADP的极缓慢交换，都表明这些核苷酸在细胞周期中可能具有调节作用。
