THE 5' END OF YEAST 5.8S RIBOSOMAL-RNA IS GENERATED BY EXONUCLEASES FROM AN UPSTREAM CLEAVAGE SITE
THE 5' END OF YEAST 5.8S RIBOSOMAL-RNA IS GENERATED BY EXONUCLEASES FROM AN UPSTREAM CLEAVAGE SITE
复制标题
DOI：
10.1002/j.1460-2075.1994.tb06530.x
复制
发表时间：
1994-05-15
期刊：
影响因子：
11.4
通讯作者：
TOLLERVEY, D
中科院分区：
文献类型：
--
作者：
HENRY, Y;WOOD, H;TOLLERVEY, D
我们开发了详细分析酿酒酵母pre-rRNA中顺式作用序列的技术，并利用这些技术研究了导致5.8S rRNA合成的内部转录间隔物1 （ITS1）的加工过程。与许多真核生物一样，酵母5.8S rRNA的5'端是异质的；我们把主要的、短的形式命名为5.8S(S)，把次要的形式（长7或8个核苷酸）命名为5.8S(L)。这些rna不具有前体/产物关系，而是由使用替代加工途径产生的。在主要途径中，ITS1中一个先前未被识别的加工位点，称为A3，被切割。A3位点10个核苷酸的缺失强烈抑制A3加工和5.8S(S)的合成；处理主要转移到另一种5.8S(L)通路。A3位点位于5.8S(S)末端5‘处的76个核苷酸，是5’- > 3‘外切酶酶切的进入位点，产生5.8S(S)的5’端。该途径在XRN1p和RAT1p突变株中被抑制。据报道，这两种蛋白在体外具有5‘- bbbb3 ’外切酶活性。5.8S(L)的形成因顺式中的A3位点突变或反式中的RAT1p和XRN1p位点突变而增加，并且在动力学上比5.8S(S)的合成更快。
We have developed techniques for the detailed analysis of cis-acting sequences in the pre-rRNA of Saccharomyces cerevisiae and used these to study the processing of internal transcribed spacer 1 (ITS1) leading to the synthesis of 5.8S rRNA. As is the case for many eukaryotes, the 5' end of yeast 5.8S rRNA is heterogeneous; we designate the major, short form 5.8S(S), and the minor form (which is seven or eight nucleotides longer) 5.8S(L). These RNAs do not have a precursor/product relationship, but result from the use of alternative processing pathways. In the major pathway, a previously unidentified processing site in ITS1, designated A3, is cleaved. A 10 nucleotide deletion at site A3 strongly inhibits processing of A3 and the synthesis of 5.8S(S); processing is predominantly transferred to the alternative 5.8S(L) pathway. Site A3 lies 76 nucleotides 5' to the end of 5.8S(S), and acts as an entry site for 5'--> 3' exonuclease digestion which generates the 5' end of 5.8S(S). This pathway is inhibited in strains mutant for XRN1p and RAT1p. Both of these proteins have been reported to have 5'--> 3' exonuclease activity in vitro. Formation of 5.8S(L) is increased by mutations at A3 in cis or in RAT1p and XRN1p in trans, and is kinetically faster than 5.8S(S) synthesis.