In cap-dependent translation initiation, the open reading frame (ORF) of mRNA is established by the placement of the AUG start codon and initiator tRNA in the ribosomal peptidyl (P) site. Internal ribosome entry sites (IRESs) promote translation of mRNAs in a cap-independent manner. We report two structures of the ribosome-bound Taura syndrome virus (TSV) IRES belonging to the family of Dicistroviridae intergenic IRESs. Intersubunit rotational states differ in these structures, suggesting that ribosome dynamics play a role in IRES translocation. Pseudoknot I of the IRES occupies the ribosomal decoding center at the aminoacyl (A) site in a manner resembling that of the tRNA anticodon-mRNA codon. The structures reveal that the TSV IRES initiates translation by a previously unseen mechanism, which is conceptually distinct from initiator tRNA-dependent mechanisms. Specifically, the ORF of the IRES-driven mRNA is established by the placement of the preceding tRNA-mRNA-like structure in the A site, whereas the 40S P site remains unoccupied during this initial step.
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http://dx.doi.org/10.1073/pnas.1406335111 | DOI Listing |
Front Endocrinol (Lausanne)
December 2024
Medical Research Institute KITANO HOSPITAL, PIIF Tazuke-kofukai, Osaka, Japan.
Silver-Russell syndrome (SRS) is a syndrome characterized by prenatal and postnatal growth retardation, facial features, and body asymmetry. SRS is often complicated with hypoglycemia, whose etiology is unclear. We describe the clinical course of 25-year-old man with hypoglycemia.
View Article and Find Full Text PDFHum Genome Var
November 2024
Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Cockayne syndrome (CS) is a progressive multisystem disorder characterized by growth failure, microcephaly, developmental delay, and photosensitivity. The characteristic symptoms appear during early childhood in most patients with CS. Herein, we report a mild case of CS with a novel start-loss variant in ERCC8 that did not show the characteristic symptoms of CS during early childhood and exhibited sudden growth failure after the age of 10 years.
View Article and Find Full Text PDFHum Genome Var
August 2023
Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Pathogenic variants in the HIBCH gene cause HIBCH deficiency, leading to mitochondrial disorders associated with valine metabolism. Patients typically present with symptoms such as developmental regression/delay, encephalopathy, hypotonia and dystonia. Brain magnetic resonance imaging (MRI) shows bilateral lesions in the basal ganglia with/without brainstem involvement.
View Article and Find Full Text PDFSci Adv
August 2023
Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
Pseudouridine is enriched in ribosomal, spliceosomal, transfer, and messenger RNA and thus integral to the central dogma. The chemical basis for how pseudouridine affects the molecular apparatus such as ribosome, however, remains elusive owing to the lack of structures without this natural modification. Here, we studied the translation of a hypopseudouridylated ribosome initiated by the internal ribosome entry site (IRES) elements.
View Article and Find Full Text PDFVector or reservoir species of three diseases of crustaceans listed in the Animal Health Law were identified based on evidence generated through an extensive literature review, to support a possible updating of Regulation (EU) 2018/1882. Crustacean species on or in which Taura syndrome virus (TSV), Yellow head virus (YHV) or White spot syndrome virus (WSSV) were identified, in the field or during experiments, were classified as reservoir species with different levels of certainty depending on the diagnostic tests used. Where experimental evidence indicated transmission of the pathogen from a studied species to another known susceptible species, the studied species was classified as vector species.
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