title: Study of an RNA helicase implicates small RNA-noncoding RNA interactions in programmed DNA elimination in Tetrahymena.
abstract: Tetrahymena eliminates micronuclear-limited sequences from the developing macronucleus during sexual reproduction. Homology between the sequences to be eliminated and approximately 28-nucleotide small RNAs (scnRNAs) associated with an Argonaute family protein Twi1p likely underlies this elimination process. However, the mechanism by which Twi1p-scnRNA complexes identify micronuclear-limited sequences is not well understood. We show that a Twi1p-associated putative RNA helicase Ema1p is required for the interaction between Twi1p and chromatin. This requirement explains the phenotypes of EMA1 KO strains, including loss of selective down-regulation of scnRNAs homologous to macronuclear-destined sequences, loss of H3K9 and K27 methylation in the developing new macronucleus, and failure to eliminate DNA. We further demonstrate that Twi1p interacts with noncoding transcripts derived from parental and developing macronuclei and this interaction is greatly reduced in the absence of Ema1p. We propose that Ema1p functions in DNA elimination by stimulating base-pairing interactions between scnRNAs and noncoding transcripts in both parental and developing new macronuclei.
authors: Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria.
authors: Lucia
authors: L
authors: Aronica
authors: Janna
authors: J
authors: Bednenko
authors: Tomoko
authors: T
authors: Noto
authors: Leroi V
authors: LV
authors: DeSouza
authors: K W Michael
authors: KW
authors: Siu
authors: Josef
authors: J
authors: Loidl
authors: Ronald E
authors: RE
authors: Pearlman
authors: Martin A
authors: MA
authors: Gorovsky
authors: Kazufumi
authors: K
authors: Mochizuki
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002843:Chromatin / Q000235:genetics; D003227:Conjugation, Genetic; D016054:DNA, Protozoan / Q000502:physiology*; D015800:Protozoan Proteins; D020365:RNA Helicases / Q000502:physiology*; D016053:RNA, Protozoan / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology*; D022661:RNA, Untranslated; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016808:Tetrahymena thermophila / Q000235:genetics* / Q000378:metabolism
chemical_list: D002843:Chromatin; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D016053:RNA, Protozoan; D034741:RNA, Small Interfering; D022661:RNA, Untranslated; D020365:RNA Helicases