Yeast基因下游二级结构与多聚腺苷作用信号

Secondary Structure of Yeast Genomic Downstream Region and Polyadenylation Signals

形成真核生物mRNA 3′末端的多聚腺苷 (poly (A) )作用涉及前体mRNA下游的三个元件 :效率元件(EE)、定位元件 (PE)以及实际的剪切和 poly (A)作用位点 ,实验研究提出了一些EE和PE的碱基序列组成 .对 180个Yeast基因下游 (终止密码子后 2 0 0个碱基 )二级结构进行的详细分析显示 ,约 86 %的EE、 89%的PE与二级结构中碱基非配对的环 (发夹环、膨胀环、内环或多分支环 )区或连接单链区有关 .这个结果提示 ,反式因子对EE和PE的识别和作用在一定程度上有赖于EE和PE的二级结构特征 .

Polyadenylation of 3 ' -forming in eukaryote concerns three elements located in precursor mRNA downstream region: efficiency element (EE), position element (PE) and the actual site for cleavage and polyadenylation. Several base sequences of EE and PE have been proposed by many experiments. The secondary structures of 180 yeast genomic downstream regions (200 bases downstream the stop codon), have been analysed in detail. It is showed that about 86 % of EE sites and 89 % of PE sites are related to the regions of non-paired loop (hairpin loop, bulge loop, interior loop or multi-branched loop) or to connecting single strand. This result suggests that the identifications and actions of EE and PE by trans-factors, to certain extent, are dependent on the structural features of EE and PE in the secondary structure. According to the secondary structure of mRNA, the prediction accuracy of EE and PE sites may be improved.