Sequence elements in both the intergenic space and the 3′ untranslated region of the Crithidia fasciculata KAP3 gene are required for cell cycle regulation of KAP2 mRNA
Sequence elements in both the intergenic space and the 3′ untranslated region of the Crithidia fasciculata KAP3 gene are required for cell cycle regulation of KAP2 mRNA
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DOI：
10.1128/ec.2.4.671-677.2003
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发表时间：
2003-08-01
期刊：
影响因子：
--
通讯作者：
Ray, DS
中科院分区：
文献类型：
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作者：
Avliyakulov, NK;Hines, JC;Ray, DS
先前已经发现参与DNA代谢的几个Crithidia fasciculata基因的mRNA水平随着细胞在细胞周期中的进展而循环。这些转录物的5'非翻译区（5' UTR）中的八聚体共有序列显示为这些mRNA的循环所需。KAP 3基因编码一种动基体组蛋白H1样DNA结合蛋白，其mRNA水平与动基体DNA拓扑异构酶（TOP 2）、二氢叶酸还原酶-胸苷酸合酶（DHFR-TS）和核单链DNA结合蛋白大亚基（RPA 1）的mRNA水平平行循环。KAP 3 mRNA在其3' UTR中含有两个八聚体共有序列，但在其5' UTR中没有。这些八聚体序列的突变不足以阻止从质粒表达的序列标记的KAP 3 mRNA的循环。除了3' UTR中的两个八聚体序列的突变之外，前体转录物上而不是mRNA上含有的八聚体序列的突变对于消除mRNA的循环是必要的。对成熟mRNA上不存在的序列的要求表明八聚体序列对mRNA水平的调节发生在转录物剪接时或剪接之前。不完全加工的RNA含有八聚体序列也被发现积累在细胞周期中的mRNA水平最低时。这些RNA种类与KAP 3编码序列和下游耐药基因的编码序列杂交，表明在分离这些基因的基因间区域内缺乏加工。我们提出了一个细胞周期依赖的干扰转录处理介导的八聚体的共识序列作为一种机制，有助于循环的这样的成绩单。
mRNA levels of several Crithidia fasciculata genes involved in DNA metabolism have previously been found to cycle as cells progress through the cell cycle. Octamer consensus sequences in the 5' untranslated regions (5' UTRs) of these transcripts were shown to be required for cycling of these mRNAs. The KAP3 gene encodes a kinetoplast histone H1-like DNA binding protein, and its mRNA levels cycle in parallel with those of the kinetoplast DNA topoisomerase (TOP2), dihydrofolate reductase-thymidylate synthase (DHFR-TS), and the large subunit of the nuclear single-stranded DNA binding protein (RPA1). KAP3 mRNA contains two octamer consensus sequences in its 3' UTR but none in its 5' UTR. Mutation of these octamer sequences was not sufficient to prevent cycling of a sequence-tagged KAP3 mRNA expressed from a plasmid. Mutation of an octamer sequence contained on the precursor transcript but not on the mRNA, in addition to mutation of the two octamer sequences in the 3' UTR, was necessary to abolish cycling of the mRNA. The requirement for a sequence not present on the mature mRNA indicates that regulation of the mRNA levels by the octamer sequences occurs at or prior to splicing of the transcript. Incompletely processed RNAs containing octamer sequences were also found to accumulate during the cell cycle when the mRNA levels were lowest. These RNA species hybridize to both the KAP3 coding sequence and that of the downstream drug resistance gene, indicating a lack of processing within the intergenic region separating these genes. We propose a cell cycle-dependent interference in transcript processing mediated by octamer consensus sequences as a mechanism contributing to the cycling of such transcripts.