National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM129539
United States
Citation
Journal: Sci Rep / Year: 2021 Title: Structural basis for the structural dynamics of human mitochondrial chaperonin mHsp60. Authors: Joseph Che-Yen Wang / Lingling Chen / Abstract: Human mitochondrial chaperonin mHsp60 is essential for mitochondrial function by assisting folding of mitochondrial proteins. Unlike the double-ring bacterial GroEL, mHsp60 exists as a heptameric ...Human mitochondrial chaperonin mHsp60 is essential for mitochondrial function by assisting folding of mitochondrial proteins. Unlike the double-ring bacterial GroEL, mHsp60 exists as a heptameric ring that is unstable and dissociates to subunits. The structural dynamics has been implicated for a unique mechanism of mHsp60. We purified active heptameric mHsp60, and determined a cryo-EM structure of mHsp60 heptamer at 3.4 Å. Of the three domains, the equatorial domains contribute most to the inter-subunit interactions, which include a four-stranded β sheet. Our structural comparison with GroEL shows that mHsp60 contains several unique sequences that directly decrease the sidechain interactions around the β sheet and indirectly shorten β strands by disengaging the backbones of the flanking residues from hydrogen bonding in the β strand conformation. The decreased inter-subunit interactions result in a small inter-subunit interface in mHsp60 compared to GroEL, providing a structural basis for the dynamics of mHsp60 subunit association. Importantly, the unique sequences are conserved among higher eukaryotic mitochondrial chaperonins, suggesting the importance of structural dynamics for eukaryotic chaperonins. Our structural comparison with the single-ring mHsp60-mHsp10 shows that upon mHsp10 binding the shortened inter-subunit β sheet is restored and the overall inter-subunit interface of mHsp60 increases drastically. Our structural basis for the mHsp10 induced stabilization of mHsp60 subunit interaction is consistent with the literature that mHsp10 stabilizes mHsp60 quaternary structure. Together, our studies provide structural bases for structural dynamics of the mHsp60 heptamer and for the stabilizing effect of mHsp10 on mHsp60 subunit association.
History
Deposition
Dec 30, 2020
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Header (metadata) release
Aug 25, 2021
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Map release
Aug 25, 2021
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Update
May 29, 2024
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Current status
May 29, 2024
Processing site: RCSB / Status: Released
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Structure visualization
Movie
Surface view with section colored by density value
Entire : Human mitochondrial chaperonin mHsp60 in a heptameric ring confor...
Entire
Name: Human mitochondrial chaperonin mHsp60 in a heptameric ring conformation
Components
Complex: Human mitochondrial chaperonin mHsp60 in a heptameric ring conformation
Protein or peptide: 60 kDa heat shock protein, mitochondrial
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Supramolecule #1: Human mitochondrial chaperonin mHsp60 in a heptameric ring confor...
Supramolecule
Name: Human mitochondrial chaperonin mHsp60 in a heptameric ring conformation type: complex / ID: 1 / Parent: 0 / Macromolecule list: all Details: Human mitochondrial chaperonin mHsp60 in a heptameric ring conformation
Model: Quantifoil / Support film - #0 - Film type ID: 1 / Support film - #0 - Material: GOLD / Support film - #0 - topology: HOLEY / Support film - #1 - Film type ID: 2 / Support film - #1 - Material: CARBON / Support film - #1 - topology: HOLEY
Vitrification
Cryogen name: ETHANE / Chamber humidity: 100 % / Instrument: FEI VITROBOT MARK IV
Details
The sample is monodisperse
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Electron microscopy
Microscope
FEI TITAN KRIOS
Specialist optics
Energy filter - Name: GIF Bioquantum / Energy filter - Slit width: 30 eV
Image recording
#0 - Image recording ID: 1 / #0 - Film or detector model: GATAN K3 BIOQUANTUM (6k x 4k) / #0 - Number grids imaged: 1 / #0 - Average electron dose: 44.0 e/Å2 / #1 - Image recording ID: 2 / #1 - Film or detector model: GATAN K3 (6k x 4k) / #1 - Number grids imaged: 3 / #1 - Average electron dose: 53.0 e/Å2
Electron beam
Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN
Electron optics
C2 aperture diameter: 50.0 µm / Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Cs: 2.7 mm
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