7o19

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

spinqualitylabelsall models 7o19, resolution 2.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7o19 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 2.9Å Ligands: 1MG, 2MA, 2MG, 3TD, 4D4, 4OC, 5MC, 5MU, 6MZ, D2T, G7M, MA6, MEQ, MG, OMC, OMG, OMU, PSU, TRP, UR3, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RS11_ECOLI Located on the platform of the 30S subunit, it bridges several disparate RNA helices of the 16S rRNA. Forms part of the Shine-Dalgarno cleft in the 70S ribosome (By similarity).[HAMAP-Rule:MF_01310] 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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