Caspers P, Dalrymple B, Iida S, Arber W
Mol Gen Genet. 1984;196(1):68-73. doi: 10.1007/BF00334094.
Three independent spontaneous mutations of prophage P1 affecting the ability of the phage to reproduce vegetatively are due to the insertion of a mobile genetic element, called IS30. The same sequence is also carried in the R plasmid NR 1-Basel, but not in the parental plasmid NR 1. Southern hybridisation study indicates that the Escherichia coli K 12 chromosome carries several copies of IS30 as a normal resident. IS30 is 1.2 kb long and contains unique restriction cleavage sites for BglII, ClaI, HindIII, NciI and HincII, and it is cleaved twice by the enzymes HpaII and TaqI. The ends of IS30 are formed by 26 bp long inverted repeats with 3 bases mismatched. Upon transposition IS30 generates a duplication of only 2 bp of the target. The following observations suggest a pronounced specificity in target selection by IS30. In transposition to the phage P1 genome a single integration site was used three times independently, and in both orientations. A short region of sequence homology has been identified between the P1 and NR 1-Basel insertion sites. IS30 has mediated cointegration as well as deletion. The entire IS30 sequences were duplicated in the cointegrates between a pBR322 derivative containing IS30 and the genome of phage P1-15, and several loci on the P1-15 genome served as fusion sites, some of which were used more than once.
原噬菌体P1的三个独立自发突变影响噬菌体营养繁殖的能力，这是由于一种名为IS30的移动遗传元件的插入。R质粒NR 1 - 巴塞尔中也携带相同序列，但亲本质粒NR 1中没有。Southern杂交研究表明，大肠杆菌K 12染色体作为正常驻留成分携带多个IS30拷贝。IS30长1.2 kb，含有BglII、ClaI、HindIII、NciI和HincII的独特限制性切割位点，并且被HpaII和TaqI酶切割两次。IS30的末端由26 bp长的反向重复序列形成，有3个碱基错配。转座时，IS30仅使靶标产生2 bp的重复。以下观察结果表明IS30在靶标选择上具有明显的特异性。在转座到噬菌体P1基因组时，一个单一的整合位点被独立使用了三次，并且在两个方向上。在P1和NR 1 - 巴塞尔插入位点之间已鉴定出短的序列同源区域。IS30介导了共整合以及缺失。在含有IS30的pBR322衍生物与噬菌体P1 - 15基因组之间的共整合体中，整个IS30序列被重复，并且P1 - 15基因组上的几个位点用作融合位点，其中一些位点被多次使用。
