Similar Datasets
Project description:The Alazami Syndrome-associated protein LARP7 guides U6 small nuclear RNA modification and contributes to splicing robustness
| PRJNA523636 | ENA
Project description:The U6 snRNA, the core catalytic component of the spliceosome, is extensively modified post-transcriptionally, with 2’-O-methylation being most common. However, how U6 2’-O-methylation is regulated remains largely unknown. Here we report that TFIP11, the human homolog of the yeast spliceosome disassembly factor Ntr1, localizes to nucleoli and Cajal Bodies and is essential for the 2’-O-methylation of U6. Mechanistically, we demonstrate that TFIP11 knockdown reduces the association of U6 snRNA with fibrillarin and associated snoRNAs, therefore altering U6 2′-O-methylation. We show U6 snRNA hypomethylation is associated with changes in assembly of the U4/U6.U5 tri-snRNP leading to defects in spliceosome assembly and alterations in splicing fidelity. Strikingly, this function of TFIP11 is independent of the RNA helicase DHX15, its known partner in yeast. In sum, our study demonstrates an unrecognized function for TFIP11 in U6 snRNP modification and U4/U6.U5 tri-snRNP assembly, identifying TFIP11 as a critical spliceosome assembly regulator. In yeast, TFIP11 and DHX15 promote the disassembly of spliceosome complex after splicing is completed. Here the authors show that human TFIP11 functions independently of DHX15 and is required for U6 snRNA 2’-O-methylation and U4/U6.U5 tri-snRNP assembly.
| S-EPMC8599867 | biostudies-literature
Project description:U6 small nuclear RNA (snRNA) is a key component of the active site of the spliceosome, a large ribonucleoprotein complex that catalyzes the splicing of precursor messenger RNA. Prior to its incorporation into the spliceosome, U6 is bound by the protein Prp24, which facilitates unwinding of the U6 internal stem-loop (ISL) so that it can pair with U4 snRNA. A previously reported crystal structure of the `core' of the U6 small nuclear ribonucleoprotein (snRNP) contained an ISL-stabilized A62G mutant of U6 bound to all four RNA-recognition motif (RRM) domains of Prp24 [Montemayor et al. (2014), Nature Struct. Mol. Biol. 21, 544-551]. The structure revealed a novel topology containing interlocked rings of protein and RNA that was not predicted by prior biochemical and genetic data. Here, the crystal structure of the U6 snRNP core with a wild-type ISL is reported. This complex crystallized in a new space group, apparently owing in part to the presence of an intramolecular cross-link in RRM1 that was not observed in the previously reported U6-A62G structure. The structure exhibits the same protein-RNA interface and maintains the unique interlocked topology. However, the orientation of the wild-type ISL is altered relative to the A62G mutant structure, suggesting inherent structural dynamics that may facilitate its pairing with U4. Consistent with their similar architectures in the crystalline state, the wild-type and A62G variants of U6 exhibit similar Prp24-binding affinities and electrophoretic mobilities when analyzed by gel-shift assay.
| S-EPMC5331471 | biostudies-literature
Project description:Removal of introns from precursor messenger RNA (pre-mRNA) and some noncoding transcripts is an essential step in eukaryotic gene expression. In the nucleus, this process of RNA splicing is carried out by the spliceosome, a multi-megaDalton macromolecular machine whose core components are conserved from yeast to humans. In addition to many proteins, the spliceosome contains five uridine-rich small nuclear RNAs (snRNAs) that undergo an elaborate series of conformational changes to correctly recognize the splice sites and catalyze intron removal. Decades of biochemical and genetic data, along with recent cryo-EM structures, unequivocally demonstrate that U6 snRNA forms much of the catalytic core of the spliceosome and is highly dynamic, interacting with three snRNAs, the pre-mRNA substrate, and >25 protein partners throughout the splicing cycle. This review summarizes the current state of knowledge on how U6 snRNA is synthesized, modified, incorporated into snRNPs and spliceosomes, recycled, and degraded.
| S-EPMC5855946 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2021-09-22 | GSE156390 | GEO
Project description:The non-coding RNA 7SK is the scaffold for a small nuclear ribonucleoprotein (7SKsnRNP) which regulates the function of the positive transcription elongation factor P-TEFb in the control of RNA polymerase II elongation in metazoans. The La-related protein LARP7 is a component of the 7SKsnRNP required for stability and function of the RNA. To address the function of LARP7 we determined the crystal structure of its La module, which binds a stretch of uridines at the 3'-end of 7SK. The structure shows that the penultimate uridine is tethered by the two domains, the La-motif and the RNA-recognition motif (RRM1), and reveals that the RRM1 is significantly smaller and more exposed than in the La protein. Sequence analysis suggests that this impacts interaction with 7SK. Binding assays, footprinting and small-angle scattering experiments show that a second RRM domain located at the C-terminus binds the apical loop of the 3' hairpin of 7SK, while the N-terminal domains bind at its foot. Our results suggest that LARP7 uses both its N- and C-terminal domains to stabilize 7SK in a closed structure, which forms by joining conserved sequences at the 5'-end with the foot of the 3' hairpin and has thus functional implications.
| S-EPMC4381077 | biostudies-literature
Project description:The spliceosome is a dynamic assembly of five small nuclear ribonucleoproteins (snRNPs) that removes introns from eukaryotic pre-mRNA. U6, the most conserved of the spliceosomal small nuclear RNAs (snRNAs), participates directly in catalysis. Here, we report the crystal structure of the Saccharomyces cerevisiae U6 snRNP core containing most of the U6 snRNA and all four RRM domains of the Prp24 protein. It reveals a unique interlocked RNP architecture that sequesters the 5' splice site-binding bases of U6 snRNA. RRMs 1, 2 and 4 of Prp24 form an electropositive groove that binds double-stranded RNA and may nucleate annealing of U4 and U6 snRNAs. Substitutions in Prp24 that suppress a mutation in U6 localize to direct RNA-protein contacts. Our results provide the most comprehensive view to date of a multi-RRM protein bound to RNA and reveal striking coevolution of protein and RNA structure.
| S-EPMC4141773 | biostudies-literature
Project description:Vertebrate U6 small nuclear RNA (snRNA) gene promoters are among the founding members of those recognized by RNA polymerase III in which all control elements for initiation are located in the 5'-flanking region. Previously, one human U6 gene (U6-1) has been studied extensively. We have identified a total of nine full-length U6 loci in the human genome. Unlike human U1 and U2 snRNA genes, most of the full-length U6 loci are dispersed throughout the genome. Of the nine full-length U6 loci, five are potentially active genes (U6-1, U6-2, U6-7, U6-8 and U6-9) since they are bound by TATA-binding protein and enriched in acetylated histone H4 in cultured human 293 cells. These five all contain OCT, SPH, PSE and TATA elements, although the sequences of these elements are variable. Furthermore, these five genes are transcribed to different extents in vitro or after transient transfection of human 293 cells. Of the nine full-length U6 loci, only U6-7 and U6-8 are closely linked and contain highly conserved 5'-flanking regions. However, due to a modest sequence difference in the proximal sequence elements for U6-7 and U6-8, these genes are transcribed at very different levels in transfected cells.
| S-EPMC154217 | biostudies-literature
Project description:U6 is the most conserved of the five small nuclear RNAs known to participate in pre-mRNA splicing. In the fission yeast Schizosaccharomyces pombe, the single-copy gene encoding this RNA is itself interrupted by an intron (T. Tani and Y. Ohshima, Nature (London) 337:87-90, 1989). Here we report analysis of the U6 genes from all four Schizosaccharomyces species, revealing that each is interrupted at an identical position by a homologous intron; in other groups, including ascomycete and basidiomycete fungi, as well as more distantly related organisms, the U6 gene is colinear with the RNA. The most parsimonious interpretation of our data is that the ancestral U6 gene did not contain an intron, but rather, it was acquired via a single relatively recent insertional event.
| S-EPMC361272 | biostudies-other
Project description:An essential pre-mRNA splicing factor, the product of the PRP38 gene, has been genetically identified in a screen of temperature-sensitive mutants of Saccharomyces cerevisiae. Shifting temperature-sensitive prp38 cultures from 23 to 37 degrees C prevents the first cleavage-ligation event in the excision of introns from mRNA precursors. In vitro splicing inactivation and complementation studies suggest that the PRP38-encoded factor functions, at least in part, after stable splicing complex formation. The PRP38 locus contains a 726-bp open reading frame coding for an acidic 28-kDa polypeptide (PRP38). While PRP38 lacks obvious structural similarity to previously defined splicing factors, heat inactivation of PRP38, PRP19, or any of the known U6 (or U4/U6) small nuclear ribonucleoprotein-associating proteins (i.e., PRP3, PRP4, PRP6, and PRP24) leads to a common, unexpected consequence: intracellular U6 small nuclear RNA (snRNA) levels decrease as splicing activity is lost. Curiously, U4 snRNA, normally extensively base paired with U6 snRNA, persists in the virtual absence of U6 snRNA.
| S-EPMC360275 | biostudies-other