Project description:Prions are infectious proteins that can adopt a structural conformation different from that of the normal protein. This change of conformation is then propagated among other molecules of the same protein. Prions are associated with neurodegenerative diseases in mammals, but are also found in fungi (in the yeast Saccharomyces cerevisiae and the filamentous fungus Podospora anserina), in which they control heritable traits. They are widespread in wild yeast strains, suggesting a biologically important role. [PSI+] is one of the most widely studied yeast prions. It corresponds to an aggregated conformation of the translational release factor, eRF3, which suppresses nonsense codons. [PSI+] modifies cellular fitness, inducing various phenotypes, depending on the genetic background. However, the genes displaying [PSI+]-controlled expression remain largely unknown. We used the recently described ribosome profiling approach to identify genes displaying changes in expression in the presence of [PSI+]. This made it possible to determine the positions of all active ribosomes within the genome, in both [PSI+] and [PSI-] isogenic strains. Comparisons of the translatomes and transcriptomes of the two strains revealed that the primary effect of [PSI+] was to repress genes involved in the stress response. Thus, we provide the first description of the global translational effect of [PSI+] and a new genetic explanation of the phenotypic differences between [PSI-] and [PSI+] strains under stress conditions.
Project description:Here, we developed a Ψ RNA immunoprecipitation sequencing method (Ψ-RIP-seq) combined with direct RNA sequencing by Oxford Nanopore Technologies to detect mRNA Ψ transcriptome-wide. We identified a large number of novel Ψs in mRNA, revealing a conserved enrichment of Ψ in mRNA 3′ UTR. We further showed that a genome-wide association of Ψ with mRNA polyadenylation, and uncovered that cleavage factor complex I (CFI) regulated Ψ generation in mRNA 3′ UTR. We finally demonstrated that Ψ in mRNA 3′ UTR promoted mRNA stability in a CFI-dependent manner.
Project description:We found that thylakoid-anchored protein PBF8 is a key regulator for Photosystem I (PSI) biogenesis. To explore the role of PBF8 in regulating chloroplast gene expression, we performed the RNA-seq to compare the the transcript levels of chloroplast-encoded genes between wild type (Col-0) and pbf8 mutants. To this end, we isolated the total RNA form 12-day-old wild type and pbf8 seedlings grown on the MS medium under long-day conditions (14 h light, 10 h dark) at 22 ºC and with a light intensity of 80 µmol m-2 s-1. The rRNAs were deleted using the Ribo-Zero Kit (Epicentre). The resulting rRNA-depleted RNA was used for preparing the sequencing library with NEBNext Single Cell/Low input library Prep Kit. The libraries were pooled and sequenced on an Illumina Nova 6000 system with 150-bp pair-end reads. Finally, our results show that the transcript accumulation for chloroplast-encoded PSI subunit and assembly factor genes between the wild type (Col-0) and pbf8 samples, suggesting PBF8 may not affect the transcript levels of chloroplast-encoded PSI subunits and assembly factors in chloroplasts.