SPECIES-SPECIFIC SIGNALS FOR THE SPLICING OF A SHORT DROSOPHILA INTRON INVITRO
SPECIES-SPECIFIC SIGNALS FOR THE SPLICING OF A SHORT DROSOPHILA INTRON INVITRO
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DOI：
10.1128/mcb.13.2.1104
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发表时间：
1993-02-01
影响因子：
5.3
通讯作者：
MOUNT, SM
中科院分区：
文献类型：
--
作者：
MING, G;LO, PCH;MOUNT, SM
以果蝇和人类细胞的核提取液为材料，研究了不同的分支点顺序、嘧啶长度和内含子大小对果蝇白色基因第二内含子剪接效率的影响。这个74个核苷酸的内含子是许多果蝇内含子的典型特征，因为它缺乏显着的嘧啶伸展，并且低于人类核提取物剪接所需的最小大小。改变3‘剪接点附近的序列以产生嘧啶伸展是在人而不是果蝇的提取物中剪接所必需的。通过在5‘剪接点和分支点之间插入该内含子来增加该内含子的大小，大大降低了果蝇提取物中长于79个核苷酸的内含子的剪接效率，但在人类提取物中的剪接效率却相反，其中长于78个核苷酸的内含子被剪接的效率要高得多。白杏Copia插入紧邻通常用于该内含子剪接的分支点，Copia长末端重复插入防止果蝇(但不是人类)提取物的剪接。然而，一致的分支点不能恢复包含CopIA长末端重复的内含子的剪接，仅改变野生型分支点序列也不能消除剪接。这些结果证明了剪接信号的物种特异性，特别是对嘧啶伸展和大小的要求，并提出了在哺乳动物中没有发现的不同机制可能在果蝇和其他物种的小内含子剪接中发挥作用的可能性。
The effects of branchpoint sequence, the pyrimidine stretch, and intron size on the splicing efficiency of the Drosophila white gene second intron were examined in nuclear extracts from Drosophila and human cells. This 74-nucleotide intron is typical of many Drosophila introns in that it lacks a significant pyrimidine stretch and is below the minimum size required for splicing in human nuclear extracts. Alteration of sequences adjacent to the 3' splice site to create a pyrimidine stretch was necessary for splicing in human, but not Drosophila, extracts. Increasing the size of this intron with insertions between the 5' splice site and the branchpoint greatly reduced the efficiency of splicing of introns longer than 79 nucleotides in Drosophila extracts but had an opposite effect in human extracts, in which introns longer than 78 nucleotides were spliced with much greater efficiency. The white-apricot copia insertion is immediately adjacent to the branchpoint normally used in the splicing of this intron, and a copia long terminal repeat insertion prevents splicing in Drosophila, but not human, extracts. However, a consensus branchpoint does not restore the splicing of introns containing the copia long terminal repeat, and alteration of the wild-type branchpoint sequence alone does not eliminate splicing. These results demonstrate species specificity of splicing signals, particularly pyrimidine stretch and size requirements, and raise the possibility that variant mechanisms not found in mammals may operate in the splicing of small introns in Drosophila and possibly other species.