EMD-12928

Single-particle
3.0 Å
EMD-12928 Deposition: 11/05/2021
Map released: 19/01/2022
Last modified: 24/04/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-12928

CspA-27 cotranslational folding intermediate 2

EMD-12928

Single-particle
3.0 Å
EMD-12928 Deposition: 11/05/2021
Map released: 19/01/2022
Last modified: 24/04/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Escherichia coli
Sample: 70S-CspA27-2
Fitted models: 7oif (Avg. Q-score: 0.468)

Deposition Authors: Agirrezabala X , Samatova E
A switch from alpha-helical to beta-strand conformation during co-translational protein folding.
Agirrezabala X , Samatova E , Macher M , Liutkute M , Maiti M , Gil-Carton D , Novacek J , Valle M , Rodnina MV
(2022) EMBO J , 41 , e109175 - e109175
PUBMED: 34994471
DOI: doi:10.15252/embj.2021109175
ISSN: 1460-2075
ASTM: EMJODG
Abstract:
Cellular proteins begin to fold as they emerge from the ribosome. The folding landscape of nascent chains is not only shaped by their amino acid sequence but also by the interactions with the ribosome. Here, we combine biophysical methods with cryo-EM structure determination to show that folding of a β-barrel protein begins with formation of a dynamic α-helix inside the ribosome. As the growing peptide reaches the end of the tunnel, the N-terminal part of the nascent chain refolds to a β-hairpin structure that remains dynamic until its release from the ribosome. Contacts with the ribosome and structure of the peptidyl transferase center depend on nascent chain conformation. These results indicate that proteins may start out as α-helices inside the tunnel and switch into their native folds only as they emerge from the ribosome. Moreover, the correlation of nascent chain conformations with reorientation of key residues of the ribosomal peptidyl-transferase center suggest that protein folding could modulate ribosome activity.