Retallack D M, Johnson L L, Ziegler S F, Strauch M A, Friedman D I
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109-0620.
Proc Natl Acad Sci U S A. 1993 Oct 15;90(20):9562-5. doi: 10.1073/pnas.90.20.9562.
The C1 protein of bacteriophage P22 binds to a unique site in the -35 region of the PRE promoter and activates transcription of the phage c2 repressor gene. This -35 target has an approximate direct repeat that overlaps the 5' end of the c1 coding region. We have isolated a single-base-pair mutation in this region that changes the PRE -35 target as well as the amino-terminal region of the C1 protein. Although the mutant C1 protein activates the mutant PRE promoter, it fails to activate the wild-type PRE promoter. This suggests that a single-base-pair mutation changes the specificities of both a protein and its target site. These studies also indicate that C1 binding to DNA is influenced by contacts made through residues near the amino terminus.
噬菌体P22的C1蛋白与PRE启动子-35区的一个独特位点结合，并激活噬菌体c2阻遏基因的转录。这个-35靶点有一个近似的直接重复序列，与c1编码区的5'端重叠。我们在该区域分离出一个单碱基对突变，它改变了PRE -35靶点以及C1蛋白的氨基末端区域。尽管突变型C1蛋白激活了突变型PRE启动子，但它无法激活野生型PRE启动子。这表明一个单碱基对突变改变了一种蛋白质及其靶位点的特异性。这些研究还表明，C1与DNA的结合受到氨基末端附近残基形成的接触的影响。
