National Institutes of Health/National Heart, Lung, and Blood Institute (NIH/NHLBI)
R01 HL140925
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
U24 GM116790
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
U24 GM116788
米国
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2021 タイトル: The structure of the native cardiac thin filament at systolic Ca levels. 著者: Cristina M Risi / Ian Pepper / Betty Belknap / Maicon Landim-Vieira / Howard D White / Kelly Dryden / Jose R Pinto / P Bryant Chase / Vitold E Galkin / 要旨: Every heartbeat relies on cyclical interactions between myosin thick and actin thin filaments orchestrated by rising and falling Ca levels. Thin filaments are comprised of two actin strands, each ...Every heartbeat relies on cyclical interactions between myosin thick and actin thin filaments orchestrated by rising and falling Ca levels. Thin filaments are comprised of two actin strands, each harboring equally separated troponin complexes, which bind Ca to move tropomyosin cables away from the myosin binding sites and, thus, activate systolic contraction. Recently, structures of thin filaments obtained at low (pCa ∼9) or high (pCa ∼3) Ca levels revealed the transition between the Ca-free and Ca-bound states. However, in working cardiac muscle, Ca levels fluctuate at intermediate values between pCa ∼6 and pCa ∼7. The structure of the thin filament at physiological Ca levels is unknown. We used cryoelectron microscopy and statistical analysis to reveal the structure of the cardiac thin filament at systolic pCa = 5.8. We show that the two strands of the thin filament consist of a mixture of regulatory units, which are composed of Ca-free, Ca-bound, or mixed (e.g., Ca free on one side and Ca bound on the other side) troponin complexes. We traced troponin complex conformations along and across individual thin filaments to directly determine the structural composition of the cardiac native thin filament at systolic Ca levels. We demonstrate that the two thin filament strands are activated stochastically with short-range cooperativity evident only on one of the two strands. Our findings suggest a mechanism by which cardiac muscle is regulated by narrow range Ca fluctuations.
分子量: 41862.613 Da / 分子数: 15 / 由来タイプ: 天然 / 由来: (天然) Sus scrofa (ブタ)
#2: タンパク質
Tropomyosinalpha-1chain
分子量: 32921.773 Da / 分子数: 8 / 由来タイプ: 天然 / 由来: (天然) Sus scrofa (ブタ)
#3: タンパク質
Isoform4ofTroponinT, cardiacmuscle
分子量: 23023.039 Da / 分子数: 2 / 由来タイプ: 天然 / 由来: (天然) Sus scrofa (ブタ)
#4: タンパク質
TroponinI, cardiacmuscle
分子量: 19639.691 Da / 分子数: 2 / 由来タイプ: 天然 / 由来: (天然) Sus scrofa (ブタ)
#5: タンパク質
TroponinC
分子量: 18288.287 Da / 分子数: 2 / 由来タイプ: 天然 / 由来: (天然) Sus scrofa (ブタ)
配列の詳細
The resolution within the thin filament is not enough to rebuild the model using the porcine ...The resolution within the thin filament is not enough to rebuild the model using the porcine sequence, so previously determined structures of equivalent proteins from different organisms were fit to the map
電子線照射量: 34 e/Å2 / フィルム・検出器のモデル: GATAN K3 (6k x 4k) / 撮影したグリッド数: 1 / 実像数: 4316 詳細: Images were collected in movie-mode with 40 subframes with a dose rate of 0.85 e-/A2 per frame.
-
解析
ソフトウェア
名称: PHENIX / バージョン: 1.11.1_2575: / 分類: 精密化
EMソフトウェア
ID
名称
バージョン
カテゴリ
1
RELION
3.08
粒子像選択
4
RELION
3.08
CTF補正
7
UCSF Chimera
モデルフィッティング
9
PHENIX
モデル精密化
10
RELION
3.08
初期オイラー角割当
11
RELION
3.08
最終オイラー角割当
12
RELION
3.08
分類
CTF補正
タイプ: PHASE FLIPPING AND AMPLITUDE CORRECTION
3次元再構成
解像度: 8 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 粒子像の数: 11933 / アルゴリズム: BACK PROJECTION / 詳細: Filtered to 11A resolution / 対称性のタイプ: POINT