Center for Systems Microbiology, Department of Systems Biology, Technical University of Denmark, DK-2800 Lyngby, Denmark.
J Bacteriol. 2010 Apr;192(8):2102-10. doi: 10.1128/JB.01387-09. Epub 2010 Jan 29.
The gene regulatory mechanism determining the developmental pathway of the temperate bacteriophage TP901-1 is regulated by two phage-encoded proteins, CI and MOR. Functional domains of the CI repressor were investigated by introducing linkers of 15 bp at various positions in cI and by limited proteolysis of purified CI protein. We show that insertions of five amino acids at positions in the N-terminal half of CI resulted in mutant proteins that could no longer repress transcription from the lytic promoter, P(L). We confirmed that the N-terminal domain of CI contains the DNA binding site, and we showed that this part of the protein is tightly folded, whereas the central part and the C-terminal part of CI seem to contain more flexible structures. Furthermore, insertions at several different positions in the central part of the CI protein reduced the cooperative binding of CI to the operator sites and possibly altered the interaction with MOR.
决定温和噬菌体 TP901-1 发育途径的基因调控机制由两种噬菌体编码的蛋白质 CI 和 MOR 调控。通过在 cI 中的不同位置引入 15 个碱基的接头和对纯化的 CI 蛋白进行有限蛋白酶解，研究了 CI 阻遏物的功能域。我们表明，在 CI 的 N 端半部分的位置插入五个氨基酸会导致突变蛋白，这些蛋白不再能够抑制裂解启动子 P(L)的转录。我们证实 CI 的 N 端结构域包含 DNA 结合位点，并且我们表明该蛋白的这一部分紧密折叠，而 CI 的中心部分和 C 端部分似乎包含更灵活的结构。此外，在 CI 蛋白的中心部分的几个不同位置插入会降低 CI 与操纵子位点的协同结合，并可能改变与 MOR 的相互作用。
