A novel family of C. elegans snRNPs contains proteins associated with trans-splicing

  1. Margaret MacMorris1,2,4,
  2. Madhur Kumar1,4,
  3. Erika Lasda1,2,
  4. Alison Larsen1,
  5. Brian Kraemer3, and
  6. Thomas Blumenthal1,2
  1. 1Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
  2. 2Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
  3. 3Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, Washington, USA

  1. ↵4 These authors contributed equally to this work.

Abstract

In many Caenorhabditis elegans pre-mRNAs, the RNA sequence between the 5′ cap and the first 3′ splice site is replaced by trans-splicing a short spliced leader (SL) from the Sm snRNP, SL1. C. elegans also utilizes a similar Sm snRNP, SL2, to trans-splice at sites between genes in polycistronic pre-mRNAs from operons. How do SL1 and SL2 snRNPs function in different contexts? Here we show that the SL1 snRNP contains a complex of SL75p and SL21p, which are homologs of novel proteins previously reported in the Ascaris SL snRNP. Interestingly, we show that the SL2 snRNP does not contain these proteins. However, SL75p and SL26p, a paralog of SL21p, are components of another Sm snRNP that contains a novel snRNA species, Sm Y. Knockdown of SL75p is lethal. However, knockdown of either SL21p or SL26p alone leads to cold-sensitive sterility, whereas knockdown of both SL21p and SL26p is lethal. This suggests that these two proteins have overlapping functions even though they are associated with different classes of snRNP. These phenotypic relationships, along with the association of SL26p with SL75p, imply that, like the SL1 RNA/Sm/SL75p/SL21p complex, the Sm Y/Sm/SL75p/SL26p complex is associated with trans-splicing.

Keywords

Footnotes

  • Reprint requests to: Thomas Blumenthal, Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; e-mail: tom.blumenthal{at}colorado.edu; fax: (303) 492-1004.

  • Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.426707.

    • Received December 5, 2006.
    • Accepted January 2, 2007.
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  1. Published in Advance February 5, 2007, doi: 10.1261/rna.426707 RNA 13: 511-520 Copyright © 2007 RNA Society

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