Characterization of the C operon transcript of bacteriophage Mu.
Characterization of the C operon transcript of bacteriophage Mu.
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噬菌体 Mu 的 C 操纵子转录本的表征。
DOI：
10.1128/jb.172.1.361-371.1990
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发表时间：
1990
影响因子：
3.2
通讯作者：
Howe,MM
中科院分区：
文献类型：
--
作者：
Stoddard,SF;Howe,MM
Mu转录发生在三个阶段：早期，中期和晚期。中间转录发生在C基因的区域，其编码晚期转录的反式激活因子。一个中间启动子Pm先前定位于C.我们使用S1核酸酶图谱与未标记和放射性标记的加帽RNA诱导溶原细胞的特点C转录，并确定其启动子。C转录起始位点定位于一个4碱基对的区域，在含有Pm的区域内C上游约740个碱基对。在诱导cts和Cam溶原菌后4 - 8分钟，C的转录被激活，并在整个裂解周期中增加。在复制缺陷型Aam溶原菌中没有发生显著的C转录。这些动力学和调节特性鉴定C转录物为中间RNA种类，并证明Pm是C启动子。Pm区的DNA序列分析显示与大肠杆菌RNA聚合酶共有序列具有良好的-10位点同源性，但较差的-35位点同源性。此外，该序列表明，C是在一个中间操纵子包含几个开放的阅读框架的远端基因。S1作图也显示了在Pm区的3'末端的上游转录物，其序列强烈类似于Rho非依赖性终止子。该RNA的调控特征与作为早期操纵子终止子的终止子t9.2一致。
Mu transcription occurs in three phases: early, middle, and late. Middle transcription occurs in the region of the C gene, which encodes the transactivator for late transcription. A middle promoter, Pm, was previously localized between 0.28 and 1.2 kilobase pairs upstream of C. We used S1 nuclease mapping with both unlabeled and radiolabeled capped RNAs from induced lysogens to characterize C transcription and identify its promoter. The C transcription initiation site was localized to a 4-base-pair region, approximately 740 base pairs upstream of C within the region containing Pm. Transcription of C was activated between 4 and 8 min after induction of cts and Cam lysogens and increased throughout the lytic cycle. Significant C transcription did not occur in replication-defective Aam lysogens. These kinetic and regulatory characteristics identify the C transcript as a middle RNA species and demonstrate that Pm is the C promoter. DNA sequence analysis of the Pm region showed a good -10, but poor -35, site homology to the Escherichia coli RNA polymerase consensus sequence. In addition, the sequence demonstrated that C is the distal gene in a middle operon containing several open reading frames. S1 mapping also showed an upstream transcript with a 3' end in the Pm region at a sequence strongly resembling a Rho-independent terminator. The regulatory characteristics of this RNA are consistent with this terminator, t9.2, being the early operon terminator.