The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform
Francisco E. Baralle - One of the best experts on this subject based on the ideXlab platform.
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Tissue-specific splicing pattern of fibronectin messenger RNA Precursor during development and aging in rat.
The Journal of cell biology, 1991Co-Authors: Franco Pagani, Laura Zagato, Carlo Vergani, Giorgio Casari, Alessandro Sidoli, Francisco E. BaralleAbstract:Fibronectin isoforms are generated by the alteRNAtive splicing of a primary transcript derived from a single gene. In rat at least three regions of the molecule are involved: EIIIA, EIIIB, and V. This study investigated the splicing patterns of these regions during development and aging, by means of ribonuclease protection analysis. Between fetal and adult rat, the extent of inclusion of the EIIIA and/or EIIIB region in fibronectin mRNA varied according to the type of tissue analyzed; but the inclusion of the V region, and in particular the V25 alteRNAtive variant, was significantly higher in all fetal than in adult tissues. These data suggest a crucial role of the V25 variant, possibly related to its interaction with the alpha 4 beta 1 integrin receptor during development. On the other hand, during aging, the only significant change observed in the splicing pattern was a decrease in the EIIIA variant in brain. The high inclusion levels of the EIIIA and EIIIB regions in young adult brain suggest that these segments may play an important role in differentiated brain tissue. The decreasing levels of inclusion of the EIIIA segment in brain fibronectin mRNA during aging may be an age-related marker with functional consequences.
Alain Jacquier - One of the best experts on this subject based on the ideXlab platform.
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processing of a dicistronic small nucleolar RNA Precursor by the RNA endonuclease rnt1
The EMBO Journal, 1998Co-Authors: Guillaume Chanfreau, G Rotondo, Pierre Legrain, Alain JacquierAbstract: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 ortholog of bacterial RNAse III. RNT1 disruption results in a dramatic decrease in the levels of mature U14 and snR190 and in accumulation of dicistronic snR190–U14 RNAs. Addition of recombinant Rnt1 to yeast extracts made from RNT1 disruptants induces the chase of dicistronic RNAs into mature snoRNAs, showing that dicistronic RNAs correspond to functional Precursors stalled in the processing pathway. Rnt1 cleaves a dicistronic transcript in vitro in the absence of other factors, separating snR190 from U14. Thus, one of the functions of eukaryotic RNAse III is, as for the bacterial enzyme, to liberate monocistronic RNAs from polycistronic transcripts.
Carol A. Fierke - One of the best experts on this subject based on the ideXlab platform.
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Ribonuclease P: a ribonucleoprotein enzyme.
Current opinion in chemical biology, 2000Co-Authors: Jeffrey C. Kurz, Carol A. FierkeAbstract:Abstract The ribonucleoprotein ribonuclease P catalyzes the hydrolysis of a specific phosphodiester bond in Precursor tRNA to form the mature 5′ end of tRNA. Recent studies have shed light on the structures of RNAse-P-RNA–P-protein and RNAse-P-RNA–Precursor-tRNA complexes, as well as on the positions of catalytic metal ions, emphasizing the importance of the structure to the catalytic function.
G. Chanfreau - One of the best experts on this subject based on the ideXlab platform.
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A cotranscriptional model for 3 '-end processing of the Saccharomyces cerevisiae pre-ribosomal RNA Precursor
RNA, 2004Co-Authors: A. K. Henras, Edouard Bertrand, G. ChanfreauAbstract:Cleavage of the Saccharomyces cerevisiae primary ribosomal RNA (rRNA) transcript in the 3' exteRNAl transcribed spacer (ETS) by Rnt1p generates the 35S pre-rRNA, the earliest detectable species in the pre-rRNA processing pathway. In this study we show that Rnt1p is concentrated in a subnucleolar dot-shaped territory distinct from the nucleolar body. The 35S pre-rRNA is localized at the periphery of the Rnt1p dot, in a pattern that suggests a diffusion of the 35S pre-rRNA from the site of Rnt1p processing. When plasmid-borne versions of the rDNA are used to express rRNAs, the Rnt1p territory reorganizes around these plasmids, suggesting a close association between Rnt1p and the plasmid-borne rDNA units. Rnt1p was found associated with the endogenous rDNA by chromatin immunoprecipitation. Deletion of functionally important Rnt1p domains result in a loss of the dot-shaped territory, showing that this subnucleolar territory corresponds to a functional site of processing. These results show that a large fraction of Rnt1p is localized at the site of transcription of the rDNA, suggesting that the cleavage of the primary pre-rRNA transcript to generate the 35S pre-rRNA is a cotranscriptional event.
Martin Jinek - One of the best experts on this subject based on the ideXlab platform.
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Structural basis for guide RNA processing and seed-dependent DNA targeting and cleavage by CRISPR-Cas12a
Molecular Cell, 2017Co-Authors: Daan C Swarts, Martin Jinek, John Van Der OostAbstract:The CRISPR-associated protein Cas12a (Cpf1), which has been repurposed for genome editing, possesses two distinct nuclease activities: endoribonuclease activity for processing its own guide RNAs, and RNA-guided DNase activity for target DNA cleavage. To elucidate the molecular basis of both activities, we determined crystal structures of Francisella novicida Cas12a in a binary complex with a guide RNA, and in a R-loop complex containing a non-cleavable guide RNA Precursor and full-length target DNA. Corroborated by biochemical experiments, these structures elucidate the mechanisms of guide RNA processing and pre-ordering of the seed sequence in the guide RNA that primes Cas12a for target DNA binding. The R-loop complex structure furthermore reveals the strand displacement mechanism that facilitates guide-target hybridization and suggests a mechanism for double-stranded DNA cleavage involving a single active site. Together, these insights advance our mechanistic understanding of Cas12a enzymes that may contribute to further development of genome editing technologies.
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structural basis for guide RNA processing and seed dependent dna targeting by crispr cas12a
Molecular Cell, 2017Co-Authors: Daan C Swarts, John Van Der Oost, Martin JinekAbstract:Summary The CRISPR-associated protein Cas12a (Cpf1), which has been repurposed for genome editing, possesses two distinct nuclease activities: endoribonuclease activity for processing its own guide RNAs and RNA-guided DNase activity for target DNA cleavage. To elucidate the molecular basis of both activities, we determined crystal structures of Francisella novicida Cas12a bound to guide RNA and in complex with an R-loop formed by a non-cleavable guide RNA Precursor and a full-length target DNA. Corroborated by biochemical experiments, these structures reveal the mechanisms of guide RNA processing and pre-ordering of the seed sequence in the guide RNA that primes Cas12a for target DNA binding. Furthermore, the R-loop complex structure reveals the strand displacement mechanism that facilitates guide-target hybridization and suggests a mechanism for double-stranded DNA cleavage involving a single active site. Together, these insights advance our mechanistic understanding of Cas12a enzymes and may contribute to further development of genome editing technologies.
