Heidekamp F, Langeveld S A, Baas P D, Jansz H S
Nucleic Acids Res. 1980 May 10;8(9):2009-21. doi: 10.1093/nar/8.9.2009.
It is already known that phi X gene A protein converts besides phi X RFI DNA also the RFI DNAs of the single-stranded bacteriophages G4, St-1, alpha 3 and phi K into RFII DNA. We have extended this observations for bacteriophages G14 and U3. Restriction enzyme analysis placed the phi X gene A protein cleavage site in St-1 RF DNA in the HinfI restriction DNA fragment F10 and in the overlapping HaeIII restriction DNA fragment Z7. The exact position and the nucleotide sequence at the 3'-OH end of the nick were determined by DNA sequence analysis of the single-stranded DNA subfragment of the nicked DNA fragment F10 obtained by gelelectrophoresis in denaturing conditions. A stretch of 85 nucleotides of St-1 DNA around the position of the phi X gene A protein cleavage site was established by DNA sequence analysis of the restriction DNA fragment Z7F1. Comparison of this nucleotide sequence with the previously determined nucleotide sequence around the cleavage site of phi X gene A protein in phi X174 RF DNA and G4 RF DNA revealed an identical sequence of only 10 nucleotides. The results suggest that the recognition sequence of the phi X174 gene A protein lies within these 10 nucleotides.
已知φX基因A蛋白除了能将φX RFI DNA转化为RFII DNA外，还能将单链噬菌体G4、St-1、α3和φK的RFI DNA转化为RFII DNA。我们将这一观察结果扩展到了噬菌体G14和U3。限制性内切酶分析表明，φX基因A蛋白在St-1 RF DNA中的切割位点位于HinfI限制性DNA片段F10以及与之重叠的HaeIII限制性DNA片段Z7中。通过对在变性条件下经凝胶电泳获得的带切口DNA片段F10的单链DNA亚片段进行DNA序列分析，确定了切口3'-OH端的确切位置和核苷酸序列。通过对限制性DNA片段Z7F1进行DNA序列分析，确定了St-1 DNA在φX基因A蛋白切割位点周围85个核苷酸的序列。将该核苷酸序列与先前确定的φX174 RF DNA和G4 RF DNA中φX基因A蛋白切割位点周围的核苷酸序列进行比较，发现只有10个核苷酸的序列相同。结果表明，φX174基因A蛋白的识别序列位于这10个核苷酸之内。
