Guillaume F Chanfreau

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Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land(More)
The yeast nuclear exosome contains multiple 3'-->5' exoribonucleases, raising the question of why so many activities are present in the complex. All components are required during the 3' processing of the 5.8S rRNA, together with the putative RNA helicase Dob1p/Mtr4p. During this processing three distinct steps can be resolved, and hand-over between(More)
The variety of biogenesis pathways for small nucleolar RNAs (snoRNAs) reflects the diversity of their genomic organization. We have searched for yeast snoRNAs which are affected by the depletion of the yeast ortholog of bacterial RNase III, Rnt1. In a yeast strain inactivated for RNT1, almost half of the snoRNAs tested are depleted with significant(More)
Nonsense-mediated mRNA decay (NMD) eliminates transcripts carrying premature translation termination codons, but the role of NMD on yeast unspliced pre-mRNA degradation is controversial. Using tiling arrays, we show that many unspliced yeast pre-mRNAs accumulate in strains mutated for the NMD component Upf1p and the exonuclease Xrn1p. Intron identity and(More)
Specific recognition of double-stranded RNA (dsRNA) by dsRNA-binding domains (dsRBDs) is involved in a large number of biological and regulatory processes. Although structures of dsRBDs in complex with dsRNA have revealed how they can bind to dsRNA in general, these do not explain how a dsRBD can recognize specific RNAs. Rnt1p, a member of the RNase III(More)
Small nucleolar RNAs (snoRNAs) are intron encoded or expressed from monocistronic independent transcription units, or, in the case of plants, from polycistronic clusters. We show that the snR190 and U14 snoRNAs from the yeast Saccharomyces cerevisiae are co-transcribed as a dicistronic precursor which is processed by the RNA endonuclease Rnt1, the yeast(More)
Ribonucleases III are double-stranded RNA (dsRNA) endonucleases required for the processing of a large number of prokaryotic and eukaryotic transcripts. Although the specificity of bacterial RNase III cleavage relies on antideterminants in the dsRNA, the molecular basis of eukaryotic RNase III specificity is unknown. All substrates of yeast RNase III(More)
The MATa1 gene encodes a transcriptional repressor that is an important modulator of sex-specific gene expression in Saccharomyces cerevisiae. MATa1 contains two small introns, both of which need to be accurately excised for proper expression of a functional MATa1 product and to avoid production of aberrant forms of the repressor. Here, we show that(More)
Small nucleolar ribonucleoprotein particles (snoRNPs) are essential cofactors in ribosomal RNA metabolism. Although snoRNP composition has been thoroughly characterized, the biogenesis process of these particles is poorly understood. We have identified two proteins from the yeast Saccharomyces cerevisiae, Yil104c/Shq1p and Ynl124w/Naf1p, which are essential(More)
The nuclear exosome is involved in a large number of RNA processing and surveillance pathways. RNase III cleavage intermediates destined to be 3'-processed or degraded can be detected when the Rrp6p subunit of the nuclear exosome is absent. Here we show that these processing and degradation intermediates are polyadenylated, and that their polyadenylation is(More)