title: Diverse mechanisms for spliceosome-mediated 3' end processing of telomerase RNA.
abstract: The 3' end of Schizosaccharomyces pombe telomerase RNA (SpTER1) is generated by spliceosomal cleavage, a reaction that corresponds to the first step of splicing. The observation that the spliceosome functions in 3' end processing raised questions about the evolutionary origin and conservation of this mechanism. We now present data in support of spliceosomes generating 3' ends of telomerase RNAs in other fungi. Strikingly, the mechanistic basis for restricting spliceosomal splicing to the first transesterification reaction differs substantially among species. Unlike S. pombe, two other fission yeasts rely on hyperstabilization of the U6 snRNA-5' splice site interaction to impede the 2nd step of splicing. In contrast, a non-canonical 5' splice site blocks the second transesterification reaction in Aspergillus species. These results demonstrate a conserved role for spliceosomes functioning in 3' end processing. Divergent mechanisms of uncoupling the two steps of splicing argue for multiple origins of this pathway.
authors.affiliation: 1] Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA [2] Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
authors.forename: Ram
authors.initials: R
authors.lastname: Kannan
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Helston
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
authors.forename: Richard O
authors.initials: RO
authors.lastname: Dannebaum
authors.affiliation: 1] Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA [2] Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA [3] Howard Hughes Medical Institute, Kansas City, Missouri 64110, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Baumann
mesh_terms: D001230:Aspergillus / Q000378:metabolism; D012313:RNA / Q000378:metabolism*; D012326:RNA Splicing; D012331:RNA, Fungal / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000378:metabolism; D012568:Schizosaccharomyces / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism*; D019098:Telomerase / Q000378:metabolism*
chemical_list: D012331:RNA, Fungal; D012342:RNA, Small Nuclear; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase