Open Accesstrans Splicing of PolycistronicCaenorhabditis elegans Pre-mRNAs: Analysis of the SL2 RNA
Author(s) -
Donald L. Evans,
Thomas Blumenthal
Publication year - 2000
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.20.18.6659-6667.2000
Subject(s) - biology , rna splicing , rna , intron , genetics , trans splicing , caenorhabditis elegans , snrnp , post transcriptional modification , small nuclear rna , stem loop , rna editing , caenorhabditis , gene , non coding rna
Genes inCaenorhabditis elegans operons are transcribed as polycistronic pre-mRNAs in which downstream gene products aretrans spliced to a specialized spliced leader, SL2. SL2 is donated by a 110-nucleotide RNA, SL2 RNA, present in the cell as an Sm-bound snRNP. SL2 RNA can be conceptually folded into a phylogenetically conserved three-stem-loop secondary structure. Here we report an in vivo mutational analysis of the SL2 RNA. Some sequences can be changed without consequence, while other changes result in a substantial loss oftrans splicing. Interestingly, the spliced leader itself can be dramatically altered, such that the first stem-loop cannot form, with only a relatively small loss intrans -splicing efficiency. However, the primary sequence of stem II is crucial for SL2trans splicing. Similarly, the conserved primary sequence of the third stem-loop plays a key role intrans splicing. While mutations in stem-loop III allow snRNP formation, a single nucleotide substitution in the loop preventstrans splicing. In contrast, the analogous region of SL1 RNA is not highly conserved, and its mutation does not abrogate function. Thus, stem-loop III appears to confer a specific function to SL2 RNA. Finally, an upstream sequence, previously predicted to be a proximal sequence element, is shown to be required for SL2 RNA expression.