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The crystal structure of the bacterial 70S ribosome refined to 2.8 angstrom resolution reveals atomic details of its interactions with messenger RNA (mRNA) and transfer RNA (tRNA). A metal ion stabilizes a kink in the mRNA that demarcates the boundary between A and P sites, which is potentially important to prevent slippage of mRNA. Metal ions also(More)
A structural and mechanistic explanation for the selection of tRNAs by the ribosome has been elusive. Here, we report crystal structures of the 30S ribosomal subunit with codon and near-cognate tRNA anticodon stem loops bound at the decoding center and compare affinities of equivalent complexes in solution. In ribosomal interactions with near-cognate tRNA,(More)
Protein synthesis is catalyzed in the peptidyl transferase center (PTC), located in the large (50S) subunit of the ribosome. No high-resolution structure of the intact ribosome has contained a complete active site including both A- and P-site tRNAs. In addition, although past structures of the 50S subunit have found no ordered proteins at the PTC,(More)
Elongation factor G (EF-G) is a guanosine triphosphatase (GTPase) that plays a crucial role in the translocation of transfer RNAs (tRNAs) and messenger RNA (mRNA) during translation by the ribosome. We report a crystal structure refined to 3.6 angstrom resolution of the ribosome trapped with EF-G in the posttranslocational state using the antibiotic fusidic(More)
Initiation of translation is the process by which initiator tRNA and the start codon of mRNA are positioned in the ribosomal P site. In eukaryotes, one of the first steps involves the binding of two small factors, eIF1 and eIF1A, to the small (40S) ribosomal subunit. This facilitates tRNA binding, allows scanning of mRNA, and maintains fidelity of start(More)
The highly divergent ribosomes of human mitochondria (mitoribosomes) synthesize 13 essential proteins of oxidative phosphorylation complexes. We have determined the structure of the intact mitoribosome to 3.5 angstrom resolution by means of single-particle electron cryogenic microscopy. It reveals 80 extensively interconnected proteins, 36 of which are(More)
In bacteria, ribosomes stalled at the end of truncated messages are rescued by transfer-messenger RNA (tmRNA), a bifunctional molecule that acts as both a transfer RNA (tRNA) and a messenger RNA (mRNA), and SmpB, a small protein that works in concert with tmRNA. Here, we present the crystal structure of a tmRNA fragment, SmpB and elongation factor Tu bound(More)
The ribosome selects a correct transfer RNA (tRNA) for each amino acid added to the polypeptide chain, as directed by messenger RNA. Aminoacyl-tRNA is delivered to the ribosome by elongation factor Tu (EF-Tu), which hydrolyzes guanosine triphosphate (GTP) and releases tRNA in response to codon recognition. The signaling pathway that leads to GTP hydrolysis(More)
Mitochondria have specialized ribosomes that have diverged from their bacterial and cytoplasmic counterparts. We have solved the structure of the yeast mitoribosomal large subunit using single-particle cryo-electron microscopy. The resolution of 3.2 angstroms enabled a nearly complete atomic model to be built de novo and refined, including 39 proteins, 13(More)
We report the crystal structure of a 58 nucleotide fragment of 23S ribosomal RNA bound to ribosomal protein L11. This highly conserved ribonucleoprotein domain is the target for the thiostrepton family of antibiotics that disrupt elongation factor function. The highly compact RNA has both familiar and novel structural motifs. While the C-terminal domain of(More)