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The archaeal ribosome is of the eukaryotic type. TACK and Asgard superphyla, the closest relatives of eukaryotes, have ribosomes containing eukaryotic ribosomal proteins not found in other archaea, eS25, eS26 and eS30. Here, we investigate the case of Saccharolobus solfataricus, a TACK crenarchaeon, using mainly leaderless mRNAs. We characterize the small ribosomal subunit of S. solfataricus bound to SD-leadered or leaderless mRNAs. Cryo-EM structures show eS25, eS26 and eS30 bound to the small subunit. We identify two ribosomal proteins, aS33 and aS34, and an additional domain of eS6. Leaderless mRNAs are bound to the small subunit with contribution of their 5'-triphosphate group. Archaeal eS26 binds to the mRNA exit channel wrapped around the 3' end of rRNA, as in eukaryotes. Its position is not compatible with an SD:antiSD duplex. Our results suggest a positive role of eS26 in leaderless mRNAs translation and possible evolutionary routes from archaeal to eukaryotic translation.
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http://dx.doi.org/10.1038/s41467-024-55718-5 | DOI Listing |
bioRxiv
July 2025
Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390.
It remains unclear how human mitochondrial ribosomal subunits assemble into an elongation-competent 55S particle on mRNAs devoid of 5' leader sequences. Here, we reconstituted and directly tracked human mitochondrial translation initiation using real-time single-molecule fluorescence spectroscopy. Corroborated with cryo-EM structural analysis, we show that the initiation factor mtIF2 and initiator fMet-tRNA are loaded to the 28S subunit to drive mRNAs binding via 5' start codon recognition.
View Article and Find Full Text PDFNucleic Acids Res
January 2025
Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan.
Nat Commun
January 2025
Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, 91120, France.
The archaeal ribosome is of the eukaryotic type. TACK and Asgard superphyla, the closest relatives of eukaryotes, have ribosomes containing eukaryotic ribosomal proteins not found in other archaea, eS25, eS26 and eS30. Here, we investigate the case of Saccharolobus solfataricus, a TACK crenarchaeon, using mainly leaderless mRNAs.
View Article and Find Full Text PDFNucleic Acids Res
October 2024
Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK.
RNA 5'-modification with NAD+/NADH (oxidized/reduced nicotinamide adenine dinucleotide) has been found in bacteria, eukaryotes and viruses. 5'-NAD is incorporated into RNA by RNA polymerases (RNAPs) during the initiation of synthesis. It is unknown (i) which factors and physiological conditions permit substantial NAD incorporation into RNA in vivo and (ii) how 5'-NAD impacts gene expression and the fate of RNA in bacteria.
View Article and Find Full Text PDFSci Rep
December 2023
UMR Transfrontalière BioEcoAgro INRAe 1158, Univ. Lille, INRAE, Univ. LiègeUPJVYNCREA, Univ. Artois, Univ. Littoral Côte d'OpaleICV-Institut Charles Viollette, 59000, Lille, France.
A mutant deficient in polynucleotide phosphorylase (PNPase) activity was previously constructed in Enterococcus faecalis 14; a strain producing a leaderless two-peptide enterocin DD14 (EntDD14). Here, we examined the impact of the absence of PNPase on the expression and synthesis of EntDD14, at the transcriptional and functional levels. As result, EntDD14 synthesis augmented in line with the growth curve, reaching a two- to fourfold increase in the ΔpnpA mutant compared to the E.
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