7O19

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

This is a non-PDB format compatible entry.

Summary for 7O19

• Entry DOI: 10.2210/pdb7o19/pdb
• Related: 7O1A 7O1C
• EMDB information: 12693
• Descriptor: Ribosomal RNA 16S, 30S ribosomal protein S10, 30S ribosomal protein S11, ... (59 entities in total)
• Functional Keywords: ribosome, regulation, tnac, arrest peptide, l-tryptophan, translation, indole, stalling
• Biological source: Escherichia coli K-12; More
• Total number of polymer chains: 55
• Total formula weight: 2169538.53

Authors

van der Stel, A.X.,Gordon, E.R.,Sengupta, A.,Martinez, A.K.,Klepacki, D.,Perry, T.N.,Herrero del Valle, A.,Vazquez-Laslop, N.,Sachs, M.S.,Cruz-Vera, L.R.,Innis, C.A. (deposition date: 2021-03-29, release date: 2021-09-01, Last modification date: 2025-03-12)

Primary citation

van der Stel, A.X.,Gordon, E.R.,Sengupta, A.,Martinez, A.K.,Klepacki, D.,Perry, T.N.,Herrero Del Valle, A.,Vazquez-Laslop, N.,Sachs, M.S.,Cruz-Vera, L.R.,Innis, C.A.
Structural basis for the tryptophan sensitivity of TnaC-mediated ribosome stalling.
Nat Commun, 12:5340-5340, 2021

PubMed Abstract: 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.

PubMed: 34504068
DOI: 10.1038/s41467-021-25663-8

Experimental method

ELECTRON MICROSCOPY (2.9 Å)