title: SL2-like spliced leader RNAs in the basal nematode Prionchulus punctatus: New insight into the evolution of nematode SL2 RNAs.
abstract: Spliced-leader (SL) trans-splicing has been found in all molecularly characterized nematode species to date, and it is likely to be a nematode synapomorphy. Most information regarding SL trans-splicing has come from the study of nematodes from a single monophyletic group, the Rhabditida, all of which employ SL RNAs that are identical to, or variants of, the SL1 RNA first characterized in Caenorhabditis elegans. In contrast, the more distantly related Trichinella spiralis, belonging to the subclass Dorylaimia, utilizes a distinct set of SL RNAs that display considerable sequence diversity. To investigate whether this is true of other members of the Dorylaimia, we have characterized SL RNAs from Prionchulus punctatus. Surprisingly, this revealed the presence of a set of SLs that show clear sequence similarity to the SL2 family of spliced leaders, which have previously only been found within the rhabditine group (which includes C. elegans). Expression of one of the P. punctatus SL RNAs in C. elegans reveals that it can compete specifically with the endogenous C. elegans SL2 spliced leaders, being spliced to the pre-mRNAs derived from downstream genes in operons, but does not compete with the SL1 spliced leaders. This discovery raises the possibility that SL2-like spliced leaders were present in the last common ancestor of the nematode phylum.
authors.affiliation: School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, Scotland, United Kingdom.
authors.forename: Neale
authors.initials: N
authors.lastname: Harrison
authors.forename: Andreas
authors.initials: A
authors.lastname: Kalbfleisch
authors.forename: Bernadette
authors.initials: B
authors.lastname: Connolly
authors.forename: Jonathan
authors.initials: J
authors.lastname: Pettitt
authors.forename: Berndt
authors.initials: B
authors.lastname: Müller
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D005796:Genes; D006376:Helminths / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009348:Nematoda / Q000235:genetics* / Q000378:metabolism; D009876:Operon; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing; D020038:RNA, Spliced Leader / Q000235:genetics* / Q000378:metabolism; D020040:Trans-Splicing; D017160:Trichinella spiralis / Q000235:genetics / Q000378:metabolism
chemical_list: D012322:RNA Precursors; D020038:RNA, Spliced Leader