Project description:PAZ/PIWI-domain (PPD) proteins carrying small RNAs (sRNAs) function in gene and genome regulation. The ciliate Tetrahymena thermophila encodes numerous PPD proteins exclusively of the Piwi clade. We show that the three Tetrahymena Piwi-family proteins (Twis) preferentially expressed in growing cells differ in their genetic essentiality and subcellular localization. Affinity purification of all eight distinct Twi proteins revealed unique properties of their bound sRNAs. Deep sequencing of Twi-bound and total sRNAs in strains disrupted for various silencing machinery uncovered an unanticipated diversity of 23-24 nt sRNA classes in growing cells, each with distinct genetic requirements for accumulation. Altogether Twis distinguish sRNAs derived from loci of pseudogene families, three types of DNA repeats, structured RNAs, and EST-supported loci with convergent or paralogous transcripts. Most surprisingly, Twi7 binds complementary strands of unequal length while Twi10 binds a specific permutation of the guanosine-rich telomeric repeat. These studies greatly expand the structural and functional repertoire of endogenous sRNAs and RNPs. 11 libraries were analyzed. 5 are total sRNA (from knockout strains or WT background strains), and 6 are Argonaute-bound sRNA
Project description:PAZ/PIWI-domain (PPD) proteins carrying small RNAs (sRNAs) function in gene and genome regulation. The ciliate Tetrahymena thermophila encodes numerous PPD proteins exclusively of the Piwi clade. We show that the three Tetrahymena Piwi-family proteins (Twis) preferentially expressed in growing cells differ in their genetic essentiality and subcellular localization. Affinity purification of all eight distinct Twi proteins revealed unique properties of their bound sRNAs. Deep sequencing of Twi-bound and total sRNAs in strains disrupted for various silencing machinery uncovered an unanticipated diversity of 23-24 nt sRNA classes in growing cells, each with distinct genetic requirements for accumulation. Altogether Twis distinguish sRNAs derived from loci of pseudogene families, three types of DNA repeats, structured RNAs, and EST-supported loci with convergent or paralogous transcripts. Most surprisingly, Twi7 binds complementary strands of unequal length while Twi10 binds a specific permutation of the guanosine-rich telomeric repeat. These studies greatly expand the structural and functional repertoire of endogenous sRNAs and RNPs.
Project description:We present a comprehensive transcriptome of ciliate T. thermophila using the Illumina RNA-seq platform. The data was generated from the six mRNA samples of growth, starvation and conjugation of Tetrahymena. Despite an AT rich genome, there are about 124.6 million reads mapped to T. thermophila genome. Using these mapped reads, we have significantly improved the previous genome annotation and investigated the gene expression. Besides, our result also provided a comprehensive understanding of the alternative splicing in T. thermophila, and suggested the existence of the regulated unproductive splicing and translation (RUST) in the single-celled eukaryote. RNA-seq for six samples of Tetrahymena growth, starvation and conjugation.
