EMD-3898
Cryo-EM structure of a polyproline-stalled ribosome in the absence of EF-P
EMD-3898
Single-particle3.2 Å
Deposition: 04/10/2017
Map released: 22/11/2017
Last modified: 23/10/2024
Sample Organism:
Escherichia coli
Sample: Polyproline stalled ribosome in the absence of elongation factor P
Fitted models: 6enf (Avg. Q-score: 0.459)
Deposition Authors: Huter P, Arenz S
Sample: Polyproline stalled ribosome in the absence of elongation factor P
Fitted models: 6enf (Avg. Q-score: 0.459)
Deposition Authors: Huter P, Arenz S
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
(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.