The role of replication proteins in the regulation of bacteriophage T4 transcription. II. Gene 45 and late transcription uncoupled from replication.
The role of replication proteins in the regulation of bacteriophage T4 transcription. II. Gene 45 and late transcription uncoupled from replication.
复制标题
复制蛋白在噬菌体 T4 转录调节中的作用。
DOI：
10.1016/0022-2836(75)90138-2
复制
发表时间：
1975
影响因子：
5.6
通讯作者：
A. Cascino
中科院分区：
文献类型：
--
作者：
R. Wu;E. Geiduschek;A. Cascino
本文进一步分析了单个复制蛋白在噬菌体T4晚期基因表达中的作用。一个特殊的目标是确定是否个别复制基因产物影响晚期基因表达已独立地从复制解偶联。在实现这一目标的实验中，已经构建了T4 poltspost-ligampost-exofampost-amX噬菌体，其具有各种复制基因的突变。病毒RNA和蛋白质已分别通过杂交竞争和丙烯酰胺凝胶电泳分析。已发现复制基因中的突变产生两种效应：（1）基因45中的突变几乎完全消除晚期基因表达。只有基因45突变才能做到这一点。基因45蛋白是后期转录持续需要的。(2)其他复制基因中的琥珀突变在不同程度上增加了复制非依赖性晚期T4转录的温度敏感性。因此，基因45的产物与先前鉴定的基因33和55蛋白一起被鉴定为晚期转录的第三个必需组分。互补DNA链之间单链断裂的分布不是明显不对称的。在所有被检测的噬菌体突变体的亲本DNA中引入断裂，其中没有DNA复制发生，包括基因45中的突变体。在最后的讨论中，我们试图分析T4 DNA的选择性基因表达的加工。这种加工和后期转录涉及许多复制蛋白的复合物的可能性进行了研究。
In this paper we have further analyzed the role of individual replication proteins in phage T4 late gene expression. One special objective has been to determine whether individual replication gene products affect late gene expressionthat has independently been uncoupled from replication. In the experiments which achieve this objective, T4poltspost−ligampost−exofampost−amXphage have been constructed, with mutationsXin the various replication genes. Viral RNA and proteins have been analyzed by hybridization-competition and by acrylamide gel electrophoresis respectively. Mutations in the replication genes have been found to produce two kinds of effects: (1) a mutation in gene 45 almost completely abolishes late gene expression. Only the gene 45 mutation does this. Gene 45 protein is continuously required for late transcription. (2) Amber mutations in the other replication genes increase the temperature sensitivity of replication-independent late T4 transcription to varying degrees. The product of gene 45 is thus identified as a third essential component of late transcription, together with the previously identified gene 33 and 55 proteins.The endonucleolytic cleavage of parental DNA in the absence of phage DNA replication has also been examined. The distribution of single-strand breaks between the complementary DNA strands is not appreciably asymmetric. Breaks are introduced into the parental DNA of all phage mutants examined, in which no DNA replication occurs, including a mutant in gene 45.In the closing discussion we attempt to analyze the processing of T4 DNA for selective gene expression. The possibility that this processing and late transcription involve a complex of many replication proteins is examined.