YEAST-CELLS LACKING 5'-]3' EXORIBONUCLEASE-1 CONTAIN MESSENGER-RNA SPECIES THAT ARE POLY(A) DEFICIENT AND PARTIALLY LACK THE 5' CAP STRUCTURE
YEAST-CELLS LACKING 5'-]3' EXORIBONUCLEASE-1 CONTAIN MESSENGER-RNA SPECIES THAT ARE POLY(A) DEFICIENT AND PARTIALLY LACK THE 5' CAP STRUCTURE
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DOI：
10.1128/mcb.13.8.4826
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发表时间：
1993-08-01
影响因子：
5.3
通讯作者：
STEVENS, A
中科院分区：
文献类型：
--
作者：
HSU, CL;STEVENS, A
对几种特定mRNA种类的减慢的周转率和缺乏5' -> 3'核糖核酸外切酶1的酿酒酵母（xrn 1细胞）中这些mRNA中的一些的较高细胞水平的分析导致发现这些酵母含有较高量的不与寡（dT）-纤维素结合的基本全长mRNA。另一方面，在脉冲标记缺乏外核糖核酸酶的细胞后发现的mRNA聚（A）链的长度、寡聚（dT）结合mRNA的细胞合成速率及其去腺苷酸化的初始速率似乎与野生型酵母细胞中的相同测量结果非常相似。通过比较分析野生型和xrn 1细胞的poly（A）-和poly（A）+ RNA组分的m7 G含量，检查poly（A）-缺陷mRNA的5'帽结构状态，表明xrn 1 poly（A）- mRNA组分的帽结构含量低。通过测量特定全长mRNA种类的5' -> 3'核糖核酸外切酶1水解速率对5'末端的进一步分析表明，约50%的xrn 1 poly（A）缺陷型mRNA种类缺乏帽结构。对核糖体蛋白51 A（RP 51 A）mRNA的5'端进行引物延伸分析，发现约30%的xrn 1细胞的poly（A）缺陷分子在5'端稍短。部分缺乏帽结构的poly（A）-缺陷mRNA种类的一些积累以及缺乏酶的细胞中mRNA周转速率的降低的发现表明5' -> 3'核糖核酸外切酶1在mRNA周转过程中可能起作用。
Analysis of the slowed turnover rates of several specific MRNA species and the higher cellular levels of some of these mRNAs in Saccharomyces cerevisiae lacking 5' --> 3' exoribonuclease 1 (xrn1 cells) has led to the finding that these yeast contain higher amounts of essentially full-length mRNAs that do not bind to oligo(dT)-cellulose. On the other hand, the length of mRNA poly(A) chains found after pulse-labeling of cells lacking the exoribonuclesse, the cellular rate of synthesis of oligo(dT)-bound mRNA, and the initial rate of its deadenylation appeared quite similar to the same measurements in wild-type yeast cells. Examination of the 5' cap structure status of the poly(A)-deficient mRNAs by comparative analysis of the m7G content of poly(A)- and poly(A)+ RNA fractions of wild-type and xrn1 cells suggested that the xrn1 poly(A) - mRNA fraction is low in cap structure content. Further analysis of the 5' termini by measurements of the rate of 5' --> 3' exoribonuclease 1 hydrolysis of specific full-length mRNA species showed that approximately 50% of the xrn1 poly(A)-deficient mRNA species lack the cap structure. Primer extension analysis of the 5' terminus of ribosomal protein 51A (RP51A) mRNA showed that about 30% of the poly(A)-deficient molecules of the xrn1 cells are slightly shorter at the 5' end. The finding of some accumulation of poly(A)-deficient mRNA species partially lacking the cap structure together with the reduction of the rate of mRNA turnover in cells lacking the enzyme suggest a possible role for 5' --> 3' exoribonuclease 1 in the mRNA turnover process.