Groenen M A, van de Putte P
J Mol Biol. 1986 Jun 20;189(4):597-602. doi: 10.1016/0022-2836(86)90490-0.
We showed previously that two regions at the left end (L1 and L3) and one at the right end (R2) of bacteriophage Mu are essential for transposition. These regions all contain a 22 base-pair sequence with the consensus YGtTTCAYtNNAARYRCGAAAR, where Y and R represent any pyrimidine and purine, respectively. The Mu A protein binds to these regions in vitro, and weakly to sequences between nucleotides 1 and 30 of the right end (R1) and between nucleotides 110 and 135 of the left end (L2). These weak A binding sites contain the sequence AARYRCGAAAR. Here we show, using site-directed mutagenesis, that the weak A binding sites are essential for transposition. Mutations in these weak A binding sites have a greater effect on transposition than mutations of corresponding base-pairs in the stronger A binding sites, located adjacent to these weak A binding sites. We confirm the importance of several of the conserved base-pairs in the consensus sequence YGtTTCAYtNNAARYRCGAAAR. The base-pairs in the A binding sites that are shown to be essential for transposition are all conserved in the ends of the related bacteriophage D108. Furthermore, it is shown that the distance of 90 base-pairs between the two regions at the left end (L1 and L2L3) is essential.
我们之前表明，噬菌体Mu左端的两个区域（L1和L3）以及右端的一个区域（R2）对于转座至关重要。这些区域均包含一段22个碱基对的序列，其共有序列为YGtTTCAYtNNAARYRCGAAAR，其中Y和R分别代表任何嘧啶和嘌呤。Mu A蛋白在体外与这些区域结合，并与右端（R1）核苷酸1至30之间以及左端（L2）核苷酸110至135之间的序列弱结合。这些弱A结合位点包含序列AARYRCGAAAR。在此我们通过定点诱变表明，弱A结合位点对于转座至关重要。这些弱A结合位点的突变对转座的影响大于位于这些弱A结合位点相邻处的较强A结合位点中相应碱基对的突变。我们证实了共有序列YGtTTCAYtNNAARYRCGAAAR中几个保守碱基对的重要性。在转座中显示为必不可少的A结合位点中的碱基对在相关噬菌体D108的末端均保守。此外，还表明左端两个区域（L1和L2L3）之间90个碱基对的距离至关重要。
