EMD-3901
Polyproline-stalled ribosome with distorted A-site and P-site tRNA
EMD-3901
Single-particle3.9 Å
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Map released: 22/11/2017
Last modified: 28/11/2018
Sample Organism:
Escherichia coli
Sample: Polyproline stalled ribosome with distorted A+P-site tRNA
Deposition Authors: Huter P, Arenz S, Wilson DN
Sample: Polyproline stalled ribosome with distorted A+P-site tRNA
Deposition Authors: Huter P, Arenz S, Wilson DN
Structural Basis for Polyproline-Mediated Ribosome Stalling and Rescue by the Translation Elongation Factor EF-P.
Huter P,
Arenz S,
Bock LV
,
Graf M
,
Frister JO,
Heuer A,
Peil L,
Starosta AL,
Wohlgemuth I
,
Peske F,
Novacek J
,
Berninghausen O,
Grubmuller H,
Tenson T
,
Beckmann R,
Rodnina MV,
Vaiana AC
,
Wilson DN
(2017) Mol. Cell , 68 , 515 - 527.e6
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(2017) Mol. Cell , 68 , 515 - 527.e6
Abstract:
Ribosomes synthesizing proteins containing consecutive proline residues become stalled and require rescue via the action of uniquely modified translation elongation factors, EF-P in bacteria, or archaeal/eukaryotic a/eIF5A. To date, no structures exist of EF-P or eIF5A in complex with translating ribosomes stalled at polyproline stretches, and thus structural insight into how EF-P/eIF5A rescue these arrested ribosomes has been lacking. Here we present cryo-EM structures of ribosomes stalled on proline stretches, without and with modified EF-P. The structures suggest that the favored conformation of the polyproline-containing nascent chain is incompatible with the peptide exit tunnel of the ribosome and leads to destabilization of the peptidyl-tRNA. Binding of EF-P stabilizes the P-site tRNA, particularly via interactions between its modification and the CCA end, thereby enforcing an alternative conformation of the polyproline-containing nascent chain, which allows a favorable substrate geometry for peptide bond formation.
Ribosomes synthesizing proteins containing consecutive proline residues become stalled and require rescue via the action of uniquely modified translation elongation factors, EF-P in bacteria, or archaeal/eukaryotic a/eIF5A. To date, no structures exist of EF-P or eIF5A in complex with translating ribosomes stalled at polyproline stretches, and thus structural insight into how EF-P/eIF5A rescue these arrested ribosomes has been lacking. Here we present cryo-EM structures of ribosomes stalled on proline stretches, without and with modified EF-P. The structures suggest that the favored conformation of the polyproline-containing nascent chain is incompatible with the peptide exit tunnel of the ribosome and leads to destabilization of the peptidyl-tRNA. Binding of EF-P stabilizes the P-site tRNA, particularly via interactions between its modification and the CCA end, thereby enforcing an alternative conformation of the polyproline-containing nascent chain, which allows a favorable substrate geometry for peptide bond formation.