title: Cis-acting elements stimulating kinetoplastid guide RNA-directed editing.
abstract: The coding sequence of several mitochondrial mRNAs of the kinetoplastid protozoa is created through the insertion and deletion of specific uridylates. The editing reactions are required to be highly specific in order to ensure that functional open reading frames are created in edited mRNAs and that potentially deleterious modification of normally nonedited sequence does not occur. Selection-amplification and mutagenesis were previously used to identify the optimal sequence requirements for in vitro editing. There is, however, a minority of natural editing sites with suboptimal sequence. Several cis-acting elements, obtained from an in vitro selection, are described here that are able to compensate for a suboptimal editing site. An A + U sequence element within the 5'-untranslated region of cytochrome b mRNA from Leishmania tarentolae is also demonstrated to function as a cis-acting guide RNA and is postulated to compensate for a suboptimal editing site in vivo. Two proteins within an enriched editing extract are UV-cross-linked to two different in vitro selected editing substrates more efficiently than poorly edited RNAs. The results suggest that these proteins contribute to the specificity of the editing reaction.
authors.affiliation: Department of Pharmacology, Medical School, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Oppegard
authors.forename: Matthew
authors.initials: M
authors.lastname: Hillestad
authors.forename: Ryan T
authors.initials: RT
authors.lastname: McCarthy
authors.forename: Raj D
authors.initials: RD
authors.lastname: Pai
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Connell
mesh_terms: D000818:Animals; D001483:Base Sequence; D016830:Kinetoplastida / Q000235:genetics*; D012313:RNA; D017393:RNA Editing; D000077278:RNA, Mitochondrial; D016053:RNA, Protozoan / Q000235:genetics; D038621:Regulatory Sequences, Ribonucleic Acid / Q000502:physiology*; D013379:Substrate Specificity; D014542:Uridine Monophosphate / Q000378:metabolism
chemical_list: D000077278:RNA, Mitochondrial; D016053:RNA, Protozoan; D038621:Regulatory Sequences, Ribonucleic Acid; D012313:RNA; D014542:Uridine Monophosphate