title: Caenorhabditis elegans mRNAs that encode a protein similar to ADARs derive from an operon containing six genes.
abstract: The Caenorhabditis elegans T20H4.4 open reading frame (GenBank accession no. U00037) predicted by Genefinder encodes a 367 amino acid protein that is 32-35% identical to the C-terminal domain of adenosine deaminases that act on RNA. We show that T20H4.4 cDNAs (GenBank accession no. AF051275) encode a larger 495 amino acid protein that is extended at its N-terminus to include a single double-stranded RNA-binding motif, and that T20H4.4 occupies the second position in a six-gene operon (5'-T20H4.5, T20H4.4, R151.8A, R151.8B, R151.7, R151.6-3'). Ten different spliced-leader (SL) sequences were found attached to T20H4.4 mRNAs, including SL1, SL2 and eight SL2-like leaders that include two new variants. Characterization of cDNAs derived from all six genes confirmed the essential features of C.elegans operons: intercistronic distances in the range of 104-257 nt between the upstream polyadenylation sites and the downstream trans -splice sites; SL2, or SL2-like leaders, attached to the downstream mRNAs. Polycistronic mRNA fragments revealed a 5'-untranslated region (5'-UTR) >705 nt. The 5'-UTR is removed in mature mRNAs from the first gene (T20H4.5) and replaced primarily by SL1, and to a lesser extent by SL2. Our study provides new information regarding operons and how they are processed.
authors.affiliation: Department of Biochemistry and Howard Hughes Medical Institute, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA.
authors.forename: R F
authors.initials: RF
authors.lastname: Hough
authors.forename: A T
authors.initials: AT
authors.lastname: Lingam
authors.forename: B L
authors.initials: BL
authors.lastname: Bass
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000243:Adenosine Deaminase / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics*; D018076:DNA, Complementary / Q000032:analysis; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D009876:Operon; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D020040:Trans-Splicing; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D018076:DNA, Complementary; D012333:RNA, Messenger; D000243:Adenosine Deaminase