The spliceosome is a megadalton protein-RNA complex which removes introns from pre-mRNA, yet the dynamic early assembly steps have not been structurally resolved. Specifically, how the spliceosome selects the correct 3' splice site (3'SS) amongst highly similar non-functional sites is not known. Here, we develop a kinetic model of splice site selection based on single-molecule U2AF heterodimer imaging and . The model successfully predicts alternative splicing patterns and indicates that 3'SS selection occurs while U2AF is in complex with the spliceosome, not during initial binding. This finding indicates the spliceosome operates in a 'partial' kinetic proofreading regime, catalyzed in part by the helicase DDX42, which increases selectivity to the underlying U2AF binding site while still allowing for efficient forward progression.
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http://dx.doi.org/10.1101/2024.07.12.603320 | 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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