title: Untemplated oligoadenylation promotes degradation of RISC-cleaved transcripts.
abstract: Double-stranded RNA, processed to small interfering RNAs (siRNAs) by Dicer and incorporated into the RNA-induced silencing complex (RISC), triggers gene silencing by a variety of pathways in eukaryotes. RNA interference involving the degradation of homologous transcripts is the best-characterized mechanism. However, the fate of the RNA fragments resulting from siRNA-directed cleavage is poorly understood. We have identified a gene (MUT68) in the unicellular green alga Chlamydomonas reinhardtii that is required for the efficient decay of siRNA-targeted transcripts. MUT68 encodes a noncanonical polyadenylate polymerase that adds untemplated adenines to the 5' RNA fragments after siRNA-mediated cleavage and appears to stimulate their exosome-dependent degradation.
authors.affiliation: Biological Sciences and Plant Science Initiative, University of Nebraska, Lincoln, NE 68588, USA.
authors.forename: Fadia
authors.initials: F
authors.lastname: Ibrahim
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rohr
authors.forename: Won-Joong
authors.initials: WJ
authors.lastname: Jeong
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hesson
authors.forename: Heriberto
authors.initials: H
authors.lastname: Cerutti
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D005095:Exoribonucleases / Q000378:metabolism; D008969:Molecular Sequence Data; D009843:Oligoribonucleotides / Q000378:metabolism*; D011062:Polynucleotide Adenylyltransferase / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D034743:RNA-Induced Silencing Complex / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013698:Templates, Genetic; D019076:Transgenes; D014367:Tryptophan Synthase / Q000235:genetics; D014500:Uracil Nucleotides / Q000378:metabolism
chemical_list: D000227:Adenine Nucleotides; D009843:Oligoribonucleotides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D034743:RNA-Induced Silencing Complex; D014500:Uracil Nucleotides; C027916:oligo(U); C023505:2',5'-oligoadenylate; D011062:Polynucleotide Adenylyltransferase; D005095:Exoribonucleases; D014367:Tryptophan Synthase