The role of 5′-leader length, secondary structure and PABP concentration on cap and poly(A) tail function during translation in Xenopus oocytes
The role of 5′-leader length, secondary structure and PABP concentration on cap and poly(A) tail function during translation in Xenopus oocytes
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DOI：
10.1093/nar/28.15.2943
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发表时间：
2000-08-01
影响因子：
14.9
通讯作者：
Pain, VM
中科院分区：
文献类型：
--
作者：
Gallie, DR;Ling, J;Pain, VM
真核mrna的5'-cap结构和poly(A) tail通过与这些调节元件结合的蛋白质之间的物理相互作用协同作用，促进翻译起始。在本研究中，我们研究了先导体长度和二级结构的存在对非洲爪蟾卵母细胞中微注射mrna的翻译能力和cap和poly(A) tail功能的影响。将5'-引线长度从17 nt增加到144 nt，导致含有非结构化引线的mRNA的表达增加2- 4倍，而含有5'-近端结构的mRNA的表达增加20倍。因此，二级结构的存在对具有较长5'前导的mrna的抑制作用较小。注射聚(A)结合蛋白（PABP） mRNA增加了聚(A)尾部和聚(A)帽的功能，促进了poly(A)(+) mRNA的翻译，而不是poly(A)(-) mRNA的翻译，特别是对于含有二级结构的mRNA。在缺乏内部核糖体进入位点的情况下，顺反子远端mRNA的表达随顺反子长度和PABP浓度的增加而增加，顺反子间二级结构对翻译的抑制作用是位置依赖的。事实上，如果位于远端顺反器上游134 nt处，二级结构的影响就会被消除。这些数据表明，先导体的长度、二级结构的存在和PABP的浓度决定了帽和poly(a) tail对翻译的调节程度。
The 5'-cap structure and poly(A) tail of eukaryotic mRNAs function synergistically to promote translation initiation through a physical interaction between the proteins that bind to these regulatory elements, In this study, we have examined the effect of leader length and the presence of secondary structure on the translational competence and the function of the cap and poly(A) tail for mRNAs microinjected into Xenopus oocytes, Increasing the length of the 5'-leader from 17 to 144 nt resulted in a 2- to 4-fold increase in expression from an mRNA containing an unstructured leader but increased expression up to 20-fold for an mRNA containing 5'-proximal structure. Consequently, the presence of secondary structure was less inhibitory for those mRNAs with a longer 5'-leader. Go-injection of poly(A)-binding protein (PABP) mRNA increased the function of the cap and poly(A) tail in promoting translation from poly(A)(+) but not poly(A)(-) mRNAs, particularly for mRNAs containing secondary structure. In the absence of an internal ribosome entry site, expression from the distal cistron of a dicistronic mRNA increased as a function of the length of the intercistronic region and the concentration of PABP, The inhibitory effect of intercistronic located secondary structure on translation was position-dependent. Indeed, the effect of secondary structure was abolished if positioned 134 nt upstream of the distal cistron, These data suggest that the length of a leader, the presence of secondary structure and the concentration of PABP determine the extent to which the cap and poly(A) tail regulate translation.