Hwang D S, Kornberg A
Department of Biochemistry, Stanford University School of Medicine, California 94305-5307.
J Biol Chem. 1992 Nov 15;267(32):23083-6.
Opening of the three tandem repeats of a 13-mer in the replication origin (oriC) of Escherichia coli is a prime event in the replication in vitro of minichromosomes (Bramhill, D., and Kornberg, A. (1988) Cell 54, 915-918). DnaA, the initiator protein, requires protein HU or IHF, along with a millimolar level of ATP and negative superhelical density in the plasmid to open this region. The extent of opening, as judged by cleavage by a single-strand-specific endonuclease (i.e. P1 nuclease), correlated closely with replication of the oriC plasmid. In an initial complex, preceding opening of the 13-mers, the footprint of DnaA protein bound by ATP covered its four 9-mer recognition sequences. The footprint of the nucleotide-free form of the protein, by contrast, was more extensive and thus, less specific.
大肠杆菌复制起点（oriC）中13聚体的三个串联重复序列的解开是微型染色体体外复制中的一个主要事件（布拉姆希尔，D.，和科恩伯格，A.（1988年）《细胞》54卷，915 - 918页）。引发蛋白DnaA需要蛋白HU或IHF，以及毫摩尔水平的ATP和质粒中的负超螺旋密度来解开该区域。通过单链特异性核酸内切酶（即P1核酸酶）切割判断的解开程度与oriC质粒的复制密切相关。在13聚体解开之前的初始复合物中，与ATP结合的DnaA蛋白的足迹覆盖了其四个9聚体识别序列。相比之下，无核苷酸形式的该蛋白的足迹更广泛，因此特异性更低。
