DIFFERENT EFFECTS OF INTRON NUCLEOTIDE COMPOSITION AND SECONDARY STRUCTURE ON PRE-MESSENGER-RNA SPLICING IN MONOCOT AND DICOT PLANTS
DIFFERENT EFFECTS OF INTRON NUCLEOTIDE COMPOSITION AND SECONDARY STRUCTURE ON PRE-MESSENGER-RNA SPLICING IN MONOCOT AND DICOT PLANTS
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DOI：
10.1002/j.1460-2075.1991.tb07806.x
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发表时间：
1991-09-01
期刊：
影响因子：
11.4
通讯作者：
FILIPOWICZ, W
中科院分区：
文献类型：
--
作者：
GOODALL, GJ;FILIPOWICZ, W
我们之前发现双子叶植物中对于识别前mRNA内含子很重要的序列与脊椎动物和酵母的内含子中的序列不同。分别在酵母和脊椎动物内含子中发现的保守分支点和多嘧啶束都不是必需的。相反，富含 AU 的序列（双子叶植物内含子的特征）是必不可少的。在这里，我们表明，单子叶植物玉米原生质体中的剪接与双子叶植物烟草（Nicotiana plumbaginifolia）中的剪接存在显着差异。与双子叶植物的情况一样，玉米中的内含子加工不需要保守的分支点和多嘧啶束。然而，与双子叶植物不同，富含 AU 的序列不是必需的，尽管如果剪接位点序列不是最佳的，它们的存在会促进剪接。单子叶植物内含子中缺乏对富含 AU 的片段的绝对需求，这反映在单子叶植物中富含 GC 的内含子的出现，但双子叶植物中则不然。我们还表明，玉米原生质体能够处理哺乳动物内含子和含有茎环的短内含子，而这两种内含子在银花原生质体中都没有剪接。玉米（但不是白花）加工含有茎环或富含GC的内含子的能力表明，在双子叶植物前体mRNA剪接过程中富含AU的序列的功能之一可能是最小化内含子内的二级结构。
We have found previously that the sequences important for recognition of pre-mRNA introns in dicot plants differ from those in the introns of vertebrates and yeast. Neither a conserved branch point nor a polypyrimidine tract, found in yeast and vertebrate introns respectively, are required. Instead, AU-rich sequences, a characteristic feature of dicot plant introns, are essential. Here we show that splicing in protoplasts of maize, a monocot, differs significantly from splicing in a dicot, Nicotiana plumbaginifolia. As in the case of dicots, a conserved branch point and a polypyrimidine tract are not required for intron processing in maize. However, unlike in dicots, AU-rich sequences are not essential, although their presence facilitates splicing if the splice site sequences are not optimal. The lack of an absolute requirement for AU-rich stretches in monocot introns is reflected in the occurrence of GC-rich introns in monocots but not in dicots. We also show that maize protoplasts are able to process a mammalian intron and short introns containing stem-loops, neither of which are spliced in N. plumbaginifolia protoplasts. The ability of maize, but not of N. plumbaginifolia to process stem-loop-containing or GC-rich introns suggests that one of the functions of AU-rich sequences during splicing of dicot plant pre-mRNAs may be to minimize secondary structure within the intron.