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Decoding of UGA selenocysteine codons in eubacteria is mediated by the specialized elongation factor SelB, which conveys the charged tRNA(Sec) to the A site of the ribosome, through binding to the SECIS mRNA hairpin. In an attempt to isolate the eukaryotic homolog of SelB, a database search in this work identified a mouse expressed sequence tag containing(More)
RNA deep sequencing technologies are revealing unexpected levels of complexity in bacterial transcriptomes with the discovery of abundant noncoding RNAs, antisense RNAs, long 5' and 3' untranslated regions, and alternative operon structures. Here, by applying deep RNA sequencing to both the long and short RNA fractions (<50 nucleotides) obtained from the(More)
Decoding of the UGA selenocysteine codon for selenoprotein translation requires the SECIS element, a stem-loop motif in the 3'-UTR of the mRNA carrying short or large apical loops. In previous structural studies, we derived a secondary structure model for SECIS RNAs with short apical loops. Work from others proposed that intra-apical loop base pairing can(More)
A new class of small RNAs (endo-siRNAs) produced from endogenous double-stranded RNA (dsRNA) precursors was recently shown to mediate transposable element (TE) silencing in the Drosophila soma. These endo-siRNAs might play a role in heterochromatin formation, as has been shown in S. pombe for siRNAs derived from repetitive sequences in chromosome(More)
Germline genes often become re-expressed in soma-derived human cancers as "cancer/testis antigens" (CTAs), and piRNA (PIWI-interacting RNA) pathway proteins are found among CTAs. However, whether and how the piRNA pathway contributes to oncogenesis in human neoplasms remain poorly understood. We found that oncogenic Ras combined with loss of the Hippo tumor(More)
It has been proposed that dosage compensation in Drosophila males occurs by binding of two core proteins, MSL-1 and MSL-2, to a set of 35-40 X chromosome "entry sites" that serve to nucleate mature complexes, termed compensasomes, which then spread to neighboring sequences to double expression of most X-linked genes. Here we show that any piece of the X(More)
The amino acid selenocysteine represents the major biological form of selenium. Both the synthesis of selenocysteine and its co-translational incorporation into selenoproteins in response to an in-frame UGA codon, require a complex molecular machinery. To decode the UGA Sec codon in eubacteria, this machinery comprises the tRNASec, the specialized(More)
In eukaryotes, translation of internal UGA selenocysteine codons requires the SECIS stem-loop structure in the 3'UTR of selenoprotein mRNAs. In an earlier work, we identified SBP as a selenocysteine insertion sequence (SECIS)-binding protein. Here, the yeast three-hybrid screen was employed to capture the cDNA of SBP. One candidate, satisfying the genetic(More)
Drosophila Gcn5 is the catalytic subunit of the SAGA and ATAC histone acetylase complexes. Here, we show that mutations in Gcn5 and the ATAC component Ada2a induce a decondensation of the male X chromosome, similar to that induced by mutations in the Iswi and Nurf301 subunits of the NURF nucleosome remodelling complex. Genetic studies as well as transcript(More)
Piwi proteins and their associated small RNAs are essential for fertility in animals. In part, this is due to their roles in guarding germ cell genomes against the activity of mobile genetic elements. piRNA populations direct Piwi proteins to silence transposon targets and, as such, form a molecular code that discriminates transposons from endogenous genes.(More)