National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM129539
米国
引用
ジャーナル: Sci Rep / 年: 2021 タイトル: Structural basis for the structural dynamics of human mitochondrial chaperonin mHsp60. 著者: Joseph Che-Yen Wang / Lingling Chen / 要旨: 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.
根拠: light scattering, We used size-exclusion chromatography (SEC) and dynamic light scattering (DLS) to compare mHsp60 with the double-ring GroEL and single-ring GroEL, microscopy, We used ...根拠: light scattering, We used size-exclusion chromatography (SEC) and dynamic light scattering (DLS) to compare mHsp60 with the double-ring GroEL and single-ring GroEL, microscopy, We used negative stain TEM and cryo-EM to confirm the assembly
名称: Human mitochondrial chaperonin mHsp60 in a heptameric ring conformation タイプ: COMPLEX 詳細: Human mitochondrial chaperonin mHsp60 in a heptameric ring conformation Entity ID: all / 由来: RECOMBINANT
分子量
値: 0.060 MDa / 実験値: NO
由来(天然)
生物種: Homo sapiens (ヒト)
由来(組換発現)
生物種: Escherichia coli (大腸菌) / 株: BL21DE3
緩衝液
pH: 7.4
緩衝液成分
ID
濃度
名称
式
Buffer-ID
1
100mM
sodiumchloride
NaCl
1
2
10mM
KHepes
1
3
1mM
EDTA
1
4
1mM
DTT
1
5
5 %
glycerol
1
試料
濃度: 9 mg/ml / 包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES / 詳細: The sample is monodisperse
試料支持
グリッドのタイプ: Quantifoil
急速凍結
装置: FEI VITROBOT MARK IV / 凍結剤: ETHANE / 湿度: 100 %