Katayama T, Crooke E
Department of Biochemistry, Stanford University School of Medicine, California 94305, USA.
J Biol Chem. 1995 Apr 21;270(16):9265-71. doi: 10.1074/jbc.270.16.9265.
DnaA protein loses the capacity to initiate chromosomal replication when treated with a soluble cell extract. This inactivation depends upon DNA and hydrolyzable ribonucleoside triphosphate. The extract does not affect the activities of other replicative proteins or the ability of DnaA to initiate replication of single-stranded DNA that contains a DnaA-binding hairpin, indicating that the inhibitory effect is specific for the action of DnaA at oriC. Gel filtration experiments implicate a 150-kDa factor as being responsible. Mutant DnaAcos protein, which causes overinitiation in vivo, is insensitive to the inactivating factor, suggesting a requirement for this negative control in vivo. We propose that a soluble factor controls initiation through down-regulation of DnaA protein.
用可溶性细胞提取物处理时，DnaA蛋白失去启动染色体复制的能力。这种失活依赖于DNA和可水解的核糖核苷三磷酸。该提取物不影响其他复制蛋白的活性，也不影响DnaA启动含有DnaA结合发夹的单链DNA复制的能力，这表明抑制作用对DnaA在oriC处的作用具有特异性。凝胶过滤实验表明一种150 kDa的因子起作用。在体内导致过度起始的突变型DnaAcos蛋白对失活因子不敏感，这表明体内需要这种负调控。我们提出一种可溶性因子通过下调DnaA蛋白来控制起始。
