REGULATION OF BACTERIOPHAGE P2 LATE GENE EXPRESSION

噬菌体P2晚期基因的转录依赖于P2 DNA 复制基因、P2 ogr基因产物和宿主RNA聚合酶。 卫星噬菌体P4可激活菌株中P2晚期基因的表达 通过引起辅助原噬菌体的去阻遏而对P2产生溶原性。 P4可以 当正常的P2通路被阻断时， 其中一个DNA复制基因突变。 这种反式激活依赖于 在P4 Delta基因上启动转录， P2晚期基因表达正常。 我们打算定义P2的这些特征 被宿主RNA聚合酶识别所需的晚期启动子 在噬菌体编码的调节蛋白的存在下。 功能 晚期启动子的结构域将由BAL-31缺失来定义， 体外诱变 P2 ogr蛋白将被纯化和表征。 我们将重建P2晚期基因转录在一个纯化的，重组的， 体外反应，以确定可能 参与启动子特异性的调节。 之间的相互作用 转录调节蛋白和DNA模板将被探测 通过动力学和化学方法。 P2-P4系统提供了一个出色的 研究宿主转录机制的模型 在噬菌体编码因子存在的情况下可以识别新的启动子。 在 此外，P4启动潜伏原噬菌体辅助细胞表达的能力， 基因在某种意义上类似于致癌病毒的转化， 其涉及宿主基因组转录的改变。

Transcription of the late genes of bacteriophage P2 depends on the P2 DNA replication genes, the P2 ogr gene product, and the host RNA polymerase. Satellite phage P4 can activate P2 late gene expression in a strain lysogenic for P2 by causing derepression of the helper prophage. P4 can also activate late gene expression when the normal P2 pathway is blocked by mutation in one of the DNA replication genes. This transactivation depends on the P4 Delta gene and initiates transcription at the same sites as nornmal P2 late gene expression. We intend to define those features of P2 late promoters that are required for recognition by the host RNA polymerase in the presence of phage-encoded regulatory proteins. The functional domains of the late promoters will be defined by BAL-31 deletion and in vitro mutagenesis. The P2 ogr protein will be purified and characterized. We will recreate P2 late gene transcription in a purified, reconstituted in vitro reaction in order to identify additional components that may be involved in the modulation of promoter specificity. Interactions between the transcriptional regulatory proteins and the DNA template will be probed by kinetic and chemical methods. The P2-P4 system provides an excellent model for studying mechanisms by which the host transcriptional machinery can recognize new promoters in the presence of phage-encoded factors. In addition, the ability of P4 to turn on expression of latent prophage helper genes is in some sense analogous to transformation by oncogenic viruses, which involves alterations in host genome transcription.