The tri-snRNP 27K protein is a component of the human U4/U6-U5 tri-snRNP and contains an N-terminal phosphorylated RS domain. In a forward genetic screen in , we previously identified a dominant mutation, M141T, in the highly-conserved C-terminal region of this protein. The mutant allele promotes changes in cryptic 5' splice site choice. To better understand the function of this poorly characterized splicing factor, we performed high-throughput mRNA sequencing analysis on worms containing this dominant mutation. Comparison of alternative splice site usage between the mutant and wild-type strains led to the identification of 26 native genes whose splicing changes in the presence of the mutation. The changes in splicing are specific to alternative 5' splice sites. Analysis of new alleles suggests that is an essential gene for worm viability. We performed a novel directed-mutation experiment in which we used the CRISPR-cas9 system to randomly generate mutations specifically at M141 of SNRP-27. We identified eight amino acid substitutions at this position that are viable, and three that are homozygous lethal. All viable substitutions at M141 led to varying degrees of changes in alternative 5' splicing of native targets. We hypothesize a role for this SR-related factor in maintaining the position of the 5' splice site as U1snRNA trades interactions at the 5' end of the intron with U6snRNA and PRP8 as the catalytic site is assembled.
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http://dx.doi.org/10.1261/rna.066878.118 | DOI Listing |
Open Biol
January 2025
School of Life Sciences, University of Dundee, Dundee, UK.
The established consensus sequence for human 5' splice sites masks the presence of two major splice site classes defined by preferential base-pairing potentials with either U5 snRNA loop 1 or the U6 snRNA ACAGA box. The two 5' splice site classes are separable in genome sequences, sensitized by specific genotypes and associated with splicing complexity. The two classes reflect the commitment to 5' splice site usage occurring primarily during 5' splice site transfer to U6 snRNA.
View Article and Find Full Text PDFMol Cell
January 2025
European Molecular Biology Laboratory (EMBL), EMBL Grenoble, 71 Avenue des Martyrs, 38042 Grenoble, France. Electronic address:
The minor spliceosome catalyzes excision of U12-dependent introns from precursors of eukaryotic messenger RNAs (pre-mRNAs). This process is critical for many cellular functions, but the underlying molecular mechanisms remain elusive. Here, we report a cryoelectron microscopy (cryo-EM) reconstruction of the 13-subunit human U11 small nuclear ribonucleoprotein particle (snRNP) complex in apo and substrate-bound forms, revealing the architecture of the U11 small nuclear RNA (snRNA), five minor spliceosome-specific factors, and the mechanism of the U12-type 5' splice site (5'SS) recognition.
View Article and Find Full Text PDFNeurol Genet
December 2024
From the The Institute of Clinical Medicine (K.Õ., T.R., E.Õ.-S., L.M., S. Pajusalu), Faculty of Medicine, University of Tartu; Genetics and Personalized Medicine Clinic (K.Õ., T.R., L.M., Sander Pajusalu); Children's Clinic (E.O.-S.); Pathology Department (S. Puusepp), Tartu University Hospital, Estonia; Folkhalsan Research Center (M.S., B.U.), Helsinki; and Tampere Neuromuscular Center (B.U.), Tampere, Finland.
Background And Objectives: Tibial muscular dystrophy (TMD) is an autosomal dominant, slowly progressive late-onset distal myopathy. TMD was first described in 1991 by Udd et al. in Finnish patients, who were later found to harbor a heterozygous unique 11-bp insertion/deletion in the last exon of the gene-the Finnish founder variant (FINmaj).
View Article and Find Full Text PDFTurk Arch Pediatr
January 2025
Federal State Budgetary Scientific Institution, Research Center for Medical Genetics, Moscow, Russia.
Objective: The study aimed to evaluate the epidemiological, clinical, and molecular data of mucopolysaccharidosis type II (MPS II) patients and their outcomes using the national registry of patients in the Russian Federation (RF). Materials and Methods: In the retrospective cohort study, the authors included data from the Russian national registry of MPS II. Results: The prevalence of MPS II in RF is 0.
View Article and Find Full Text PDFOpening of the cardiac voltage-gated Na+ channel (Nav1.5) is responsible for robust depolarization of the cardiac action potential, while inactivation, which rapidly follows, allows for repolarization. Regulation of both the voltage- and time-dependent kinetics of Nav1.
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