COUPLING OF POLY(A) SITE SELECTION AND TRANSSPLICING IN LEISHMANIA
COUPLING OF POLY(A) SITE SELECTION AND TRANSSPLICING IN LEISHMANIA
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DOI：
10.1101/gad.7.6.996
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发表时间：
1993-06-01
影响因子：
10.5
通讯作者：
BEVERLEY, SM
中科院分区：
文献类型：
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作者：
LEBOWITZ, JH;SMITH, HQ;BEVERLEY, SM
锥虫多顺反子前体mRNA的基因间区域是两个加工反应的位点：上游基因的聚腺苷酸化和加帽的小外显子到下游基因的反式剪接。它们的紧密接近和缺乏共识基序在聚（A）位点，使我们测试聚（A）位点的选择是否是由下游剪接受体的DHFR-TS基因座的大型利什曼原虫的位置。每当下游剪接位点的位置被改变时，多聚腺苷酸位点就在新剪接位点上游移动400-500个核苷酸。相反，当野生型poly（A）位点被消除时，下游剪接位点不受影响，并且在剪接位点上游200-500个核苷酸处保持聚腺苷酸化。在第二组实验中，利什曼原虫中表达的T7 RNA聚合酶用于指导人工前体RNA的体内合成，发现其表达需要下游剪接受体的存在。我们的结论是，在利什曼原虫多聚（A）位点的选择是指定的下游剪接受体的位置，并提出了一个扫描模型多聚（A）位点的选择后，s lice网站识别。
Intergenic regions of polycistronic pre-mRNAs of trypanosomatid protozoans are the sites of two processing reactions: polyadenylation of the upstream gene and trans-splicing of the capped miniexon to the downstream gene. Their close proximity and the lack of consensus motifs at poly(A) sites led us to test whether poly(A) site selection is governed by the location of the downstream splice acceptor in the DHFR-TS locus of Leishmania major. Whenever the position of the downstream splice site was altered, the poly(A) site was shifted 400-500 nucleotides upstream of the new splice site. In contrast, when the wild-type poly(A) site was eliminated, the downstream splice site was unaffected, and polyadenylation was maintained 200-500 nucleotides upstream of the splice site. In a second set of experiments, T7 RNA polymerase expressed in Leishmania was used to direct the synthesis of artificial pre-RNAs in vivo whose expression was found to require the presence of a downstream splice acceptor. We conclude that poly(A) site selection in Leishmania is specified by the position of the downstream splice acceptor and propose a scanning model for poly(A) site selection after s lice site recognition.