Interplay between AAUAAA and the trans-splice site in processing of a Caenorhabditis elegans operon pre-mRNA
Interplay between AAUAAA and the trans-splice site in processing of a Caenorhabditis elegans operon pre-mRNA
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DOI：
10.1017/s1355838201002333
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发表时间：
2001-02-01
期刊：
影响因子：
4.5
通讯作者：
Blumenthal, T
中科院分区：
文献类型：
--
作者：
Liu, YM;Huang, T;Blumenthal, T
大约一半的秀丽隐杆线虫基因与典型的AAUAAA六聚体有1-2个bp的不匹配，这标志着3'端形成。一种罕见的变异，AGUAAA，在mail - 1基因的3'端被发现，这是一个包含gpd-2和gpd-3的操纵子的第一个基因。当我们在热休克控制下表达该操纵子时，依赖于AGUAAA的3'端形成非常低效，但可以通过一个bp的改变来挽救，从而创建一个完美的AAUAAA。当AGUAAA存在时，大多数3'端在gpd-2反式剪接位点下游100 bp处形成。令人惊讶的是，这个位点的3'端形成不需要任何与AAUAAA共识相匹配的观察结果。这可能是由于反式剪接位点的缺失阻止了3'端在这里的形成，从而通过一种新的机制——反式剪接依赖的切割——发生的。将AGUAAA改变为AAUAAA也影响了反式剪接过程：使用AGUAAA，大部分gpd-2产物被反式剪接到SL1上，而不是通常用于下游操纵子反式剪接位点的SL2。然而，AAUAAA增加了gpd-2的SL2反式剪接。结果表明：(1)AAUAAA共识控制秀丽隐杆线虫3′端形成频率；(2) AAUAAA对于确定下游100 bp以上的SL2反式剪接事件具有重要意义；末端(3)在某些情况下，3'端形成可能通过反式剪接依赖机制发生。
About half of Caenorhabditis elegans genes have a 1-2 bp mismatch to the canonical AAUAAA hexamer that signals 3' end formation. One rare variant, AGUAAA, is found at the 3' end of the mai-l gene, the first gene in an operon also containing gpd-2 and gpd-3. When we expressed this operon under heat shock control, 3' end formation dependent on the AGUAAA was very inefficient, but could be rescued by a single bp change to create a perfect AAUAAA. When AGUAAA was present, most 3' ends formed at a different site, 100 bp farther downstream, right at the gpd-2 trans-splice site. Surprisingly, 3' end formation at this site did not require any observable match to the AAUAAA consensus. It is possible that 3' end formation at this site occurs by a novel mechanism-trans-splicing-dependent cleavage-as deletion of the trans-splice site prevented 3' end formation here. Changing the AGUAAA to AAUAAA also influenced the trans-splicing process: with AGUAAA, most of the gpd-2 product was trans-spliced to SL1, rather than SL2, which is normally used at downstream operon trans-splice sites. However, with AAUAAA, SL2 trans-splicing of gpd-2 was increased. Our results imply that (1) the AAUAAA consensus controls 3' end formation frequency in C. elegans; (2) the AAUAAA is important in determining SL2 trans-splicing events more than 100 bp downstream; end (3) in some circumstances, 3' end formation may occur by a trans-splicing-dependent mechanism.