EMD-32989
Cryo-EM structure of human TRiC-tubulin-S2
EMD-32989
Single-particle4.2 Å
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Map released: 07/06/2023
Last modified: 05/07/2023
Sample Organism:
Homo sapiens
Sample: Human TRiC-tubulin-S2
Fitted models: 7x3j (Avg. Q-score: 0.246)
Deposition Authors: Cong Y
,
Liu CX
Sample: Human TRiC-tubulin-S2
Fitted models: 7x3j (Avg. Q-score: 0.246)
Deposition Authors: Cong Y
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Pathway and mechanism of tubulin folding mediated by TRiC/CCT along its ATPase cycle revealed using cryo-EM.
Liu C
,
Jin M,
Wang S,
Han W,
Zhao Q,
Wang Y
,
Xu C,
Diao L
,
Yin Y
,
Peng C
,
Bao L
,
Wang Y
,
Cong Y
(2023) Commun Biol , 6 , 531 - 531
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(2023) Commun Biol , 6 , 531 - 531
Abstract:
The eukaryotic chaperonin TRiC/CCT assists the folding of about 10% of cytosolic proteins through an ATP-driven conformational cycle, and the essential cytoskeleton protein tubulin is the obligate substrate of TRiC. Here, we present an ensemble of cryo-EM structures of endogenous human TRiC throughout its ATPase cycle, with three of them revealing endogenously engaged tubulin in different folding stages. The open-state TRiC-tubulin-S1 and -S2 maps show extra density corresponding to tubulin in the cis-ring chamber of TRiC. Our structural and XL-MS analyses suggest a gradual upward translocation and stabilization of tubulin within the TRiC chamber accompanying TRiC ring closure. In the closed TRiC-tubulin-S3 map, we capture a near-natively folded tubulin-with the tubulin engaging through its N and C domains mainly with the A and I domains of the CCT3/6/8 subunits through electrostatic and hydrophilic interactions. Moreover, we also show the potential role of TRiC C-terminal tails in substrate stabilization and folding. Our study delineates the pathway and molecular mechanism of TRiC-mediated folding of tubulin along the ATPase cycle of TRiC, and may also inform the design of therapeutic agents targeting TRiC-tubulin interactions.
The eukaryotic chaperonin TRiC/CCT assists the folding of about 10% of cytosolic proteins through an ATP-driven conformational cycle, and the essential cytoskeleton protein tubulin is the obligate substrate of TRiC. Here, we present an ensemble of cryo-EM structures of endogenous human TRiC throughout its ATPase cycle, with three of them revealing endogenously engaged tubulin in different folding stages. The open-state TRiC-tubulin-S1 and -S2 maps show extra density corresponding to tubulin in the cis-ring chamber of TRiC. Our structural and XL-MS analyses suggest a gradual upward translocation and stabilization of tubulin within the TRiC chamber accompanying TRiC ring closure. In the closed TRiC-tubulin-S3 map, we capture a near-natively folded tubulin-with the tubulin engaging through its N and C domains mainly with the A and I domains of the CCT3/6/8 subunits through electrostatic and hydrophilic interactions. Moreover, we also show the potential role of TRiC C-terminal tails in substrate stabilization and folding. Our study delineates the pathway and molecular mechanism of TRiC-mediated folding of tubulin along the ATPase cycle of TRiC, and may also inform the design of therapeutic agents targeting TRiC-tubulin interactions.