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Translation can be initiated from a specific start codon using trans-RNA.

The cryo-electron microscopy structure of the eukaryotic initiation factor 3 (eIF3) within the larger 43S complex is determined; the improved resolution enables visualization of the secondary structures of the subunits, as well as the contacts between eIF3 and both eIF2 and DHX29.

Plant mitoribosomes are crucial for mitochondrial protein synthesis. Here, authors use cryo-EM to determine high-resolution structures of cauliflower mitoribosomes, and combined with sequencing and mass spectrometry, identified 19 rRNA base modifications.

Here, the authors present a method to rapidly isolate actively translating ribosomes in a time- and cost-effective manner using poly-lysine. The method is compatible with a wide variety of cell and tissue types and can be used for mass spectrometry, cryoEM, and in vitro translation assays.

The authors uncover one of the largest mitoribosomes, dedicated to translating only three proteins in lethal human eukaryotic pathogens of the Apicomplexa phylum. All members of mitochondrial DNA-containing Myzozoa, including Toxoplasma gondii, have commandeered three lineage-specific families of RNA-binding proteins to meticulously piece together over 40 mitochondrial rRNA fragments to build an operational mitoribosome.

Electrons enter the mitochondrial respiratory chain via complex I. Here, the authors report high-resolution structures of mature plant complex I and one of its assembly intermediates, highlighting plant-specific features including an ancestral carbonic anhydrase domain.

Antibiotic resistance ABC-F factors protect the ribosome from important antibiotics. Here, for one of them, the authors describe its molecular regulation that involves ribosome stalling by antibiotics for which the factor provides resistance.

Mitoribosomes are remarkably diverse in their structures and compositions. Here the authors combine biochemistry, genetics, single particle cryo-electron microscopy and in situ cryo-electron tomography to reveal the mitochondrial ribosome of Chlamydomonas reinhardtii as an extreme example of evolution and species-specific adaptation.

This study characterized the unique protein subunit composition and structure of Arabidopsis mitochondrial ribosomes using biochemical assays and cryo-electron microscopy. Ten subunits are pentatricopeptide (PPR) proteins, among which rPPR1 functions as a translation factor.

Functional analyses of the ABC-F protein YjjK (EttA) suggest that it acts as a sensor of cellular energy and controls entry into the translational elongation cycle. Using cryo-EM and single-molecule FRET, EttA is shown to bind the ribosomal E site and engage both the L1 stalk and P-site tRNA to restrain ribosomal dynamics.

The folding of ribosomal RNAs is central to the biogenesis of the mitoribosome and is a complex, stepwise process. Five recent cryo-EM studies detail the late steps of the folding and maturation of the human mitoribosomal large subunit RNA that forms the catalytic core of the ribosome: the peptidyl transferase center (PTC).

Mitochondria ribosomes translate essential mRNAs encoded by mitochondrial genomes. The cryo-EM structure of the 78S mitoribosome from cauliflower shows plant-specific pentatricopeptide repeat proteins binding rRNAs expanded over those of animals.

High-resolution cryo-electron microscopy shows that the Trypanosoma brucei kinetoplastid ribosome is characterized by the presence of large expansion segments, ribosomal-protein extensions and additional rRNA insertions, which may have implications for the protein-translation regulation process.

Although ABC-F proteins represent a ubiquitously distributed type of ATP-binding cassette (ABC) family member across phyla, their biological functions remain poorly characterized. A new study now shows that the bacterial ABC-F protein YjjK (EttA) gates ribosome entry into the translational cycle in an energy-dependent manner.

A sub-nanometre reconstruction of a 40S complex containing eIF3 and a hepatitis C virus (HCV)-like internal ribosome entry site (IRES) shows that the IRES displaces eIF3 from the 40S and sequesters it to gain access to the 40S subunit.