7o1a

Cryo-EM structure of an Escherichia coli TnaC(R23F)-ribosome complex stalled in response to L-tryptophan

spinqualitylabelsall models 7o1a, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7o1a is a 10 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.4Å Ligands: 1MG, 2MA, 2MG, 3TD, 4D4, 4OC, 5MC, 5MU, 6MZ, D2T, G7M, K, MA6, MEQ, MG, OMC, OMG, OMU, PSU, TRP, UR3, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RL18_ECOLI This is one of the proteins that mediates the attachment of the 5S rRNA subcomplex onto the large ribosomal subunit where it forms part of the central protuberance. Binds stably to 5S rRNA; increases binding abilities of L5 in a cooperative fashion; both proteins together confer 23S rRNA binding. The 5S rRNA and some of its associated proteins might help stabilize positioning of ribosome-bound tRNAs. Publication Abstract from PubMed Free L-tryptophan (L-Trp) stalls ribosomes engaged in the synthesis of TnaC, a leader peptide controlling the expression of the Escherichia coli tryptophanase operon. Despite extensive characterization, the molecular mechanism underlying the recognition and response to L-Trp by the TnaC-ribosome complex remains unknown. Here, we use a combined biochemical and structural approach to characterize a TnaC variant (R23F) with greatly enhanced sensitivity for L-Trp. We show that the TnaC-ribosome complex captures a single L-Trp molecule to undergo termination arrest and that nascent TnaC prevents the catalytic GGQ loop of release factor 2 from adopting an active conformation at the peptidyl transferase center. Importantly, the L-Trp binding site is not altered by the R23F mutation, suggesting that the relative rates of L-Trp binding and peptidyl-tRNA cleavage determine the tryptophan sensitivity of each variant. Thus, our study reveals a strategy whereby a nascent peptide assists the ribosome in detecting a small metabolite. Structural basis for the tryptophan sensitivity of TnaC-mediated ribosome stalling.,van der Stel AX, Gordon ER, Sengupta A, Martinez AK, Klepacki D, Perry TN, Herrero Del Valle A, Vazquez-Laslop N, Sachs MS, Cruz-Vera LR, Innis CA Nat Commun. 2021 Sep 9;12(1):5340. doi: 10.1038/s41467-021-25663-8. PMID:34504068 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribosome 3D structures

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