Wegrzyn G, Wegrzyn A, Pankiewicz A, Taylor K
University of Gdańsk, Department of Molecular Biology, Poland.
Mol Gen Genet. 1996 Oct 16;252(5):580-6. doi: 10.1007/BF02172404.
We demonstrate a variation in the effects of seven alleles of the Escherichia coli dnaA gene, which cause temperature sensitivity of initiation of chromosomal replication, on the replication of lambda phage-derived plasmids at 30 degrees C. These mutants showed no allele specificity of dnaA function in replication of either of two lambda pi plasmids studied. On the other hand, the inability of the lambda P+ plasmid to replicate in dnaA508, 46 and 204 cells, in dnaB (groP A15) or in cells that are temperature sensitive for the chaperone genes dnaK756, dnaJ259 and grpE280 at 30 degrees C was suppressible by a single pi mutatation. This suggests that it is a common property of the pi protein, probably its weaker interaction with DnaB helicase, that is responsible for the suppression. One can also conclude that the DnaA-regulated transcriptional activation of ori lambda acts at the step, in which all these gene products cooperate, i.e. during preprimosome loading and chaperone-mediated release of DnaB from P protein inhibition.
我们证明了大肠杆菌dnaA基因的七个等位基因对λ噬菌体衍生质粒在30℃下复制的影响存在差异，这些等位基因会导致染色体复制起始的温度敏感性。在研究的两种λπ质粒的复制中，这些突变体在dnaA功能上没有等位基因特异性。另一方面，λP +质粒在dnaA508、46和204细胞中、在dnaB（groP A15）中或在对伴侣基因dnaK756、dnaJ259和grpE280在30℃下温度敏感的细胞中无法复制，这种情况可被单个π突变抑制。这表明π蛋白的一个共同特性，可能是其与DnaB解旋酶的较弱相互作用，是造成这种抑制的原因。人们还可以得出结论，DnaA调节的oriλ转录激活作用于所有这些基因产物协同作用的步骤，即在预引发体装载以及伴侣蛋白介导的DnaB从P蛋白抑制中释放的过程中。
