Visualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native state

Abstract The folding nucleus (FN) initiates and enables an efficient protein folding pathway. Despite its essential role, the FN has long remained cryptic. Here we directly visualize the tubulin FN consisting of a nonnative, partially assembled Rossmann fold, in the closed chamber of human chaperoni...

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Main Authors: Yanyan Zhao, Michael F. Schmid, Wah Chiu
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-63016-x
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author Yanyan Zhao
Michael F. Schmid
Wah Chiu
author_facet Yanyan Zhao
Michael F. Schmid
Wah Chiu
author_sort Yanyan Zhao
collection DOAJ
description Abstract The folding nucleus (FN) initiates and enables an efficient protein folding pathway. Despite its essential role, the FN has long remained cryptic. Here we directly visualize the tubulin FN consisting of a nonnative, partially assembled Rossmann fold, in the closed chamber of human chaperonin TRiC. Chaperonin TRiC interacts with nonnatively folded secondary structure elements of tubulin, stabilizing the nucleus poised for transition into its first native domain tertiary structure. Through progressive folding into the native state, we observe that the unfolded sequence of tubulin undergoes drastic spatial rearrangement in the TRiC chamber to sample the conformational space, mediated by the highly dynamic CCT tails. The observed presence of individual nonnative secondary structure elements first in the nonnative FN and then around the incrementally folded native domains supports the hypothesis that tubulin folding in TRiC is a hierarchical process of nucleation, condensation and propagation in cooperation with TRiC subunits.
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spelling doaj-art-770355fe61d64a6ca79486518264bc0a2025-08-24T11:38:27ZengNature PortfolioNature Communications2041-17232025-08-0116111110.1038/s41467-025-63016-xVisualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native stateYanyan Zhao0Michael F. Schmid1Wah Chiu2Department of Bioengineering, Stanford UniversityDivision of CryoEM and Bioimaging, SSRL, SLAC National Accelerator LaboratoryDepartment of Bioengineering, Stanford UniversityAbstract The folding nucleus (FN) initiates and enables an efficient protein folding pathway. Despite its essential role, the FN has long remained cryptic. Here we directly visualize the tubulin FN consisting of a nonnative, partially assembled Rossmann fold, in the closed chamber of human chaperonin TRiC. Chaperonin TRiC interacts with nonnatively folded secondary structure elements of tubulin, stabilizing the nucleus poised for transition into its first native domain tertiary structure. Through progressive folding into the native state, we observe that the unfolded sequence of tubulin undergoes drastic spatial rearrangement in the TRiC chamber to sample the conformational space, mediated by the highly dynamic CCT tails. The observed presence of individual nonnative secondary structure elements first in the nonnative FN and then around the incrementally folded native domains supports the hypothesis that tubulin folding in TRiC is a hierarchical process of nucleation, condensation and propagation in cooperation with TRiC subunits.https://doi.org/10.1038/s41467-025-63016-x
spellingShingle Yanyan Zhao
Michael F. Schmid
Wah Chiu
Visualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native state
Nature Communications
title Visualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native state
title_full Visualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native state
title_fullStr Visualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native state
title_full_unstemmed Visualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native state
title_short Visualizing dynamic tubulin folding in chaperonin TRiC from nonnative nucleus to final native state
title_sort visualizing dynamic tubulin folding in chaperonin tric from nonnative nucleus to final native state
url https://doi.org/10.1038/s41467-025-63016-x
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AT wahchiu visualizingdynamictubulinfoldinginchaperonintricfromnonnativenucleustofinalnativestate