ジャーナル: Proc Natl Acad Sci U S A / 年: 2016 タイトル: Unfolding the mechanism of the AAA+ unfoldase VAT by a combined cryo-EM, solution NMR study. 著者: Rui Huang / Zev A Ripstein / Rafal Augustyniak / Michal Lazniewski / Krzysztof Ginalski / Lewis E Kay / John L Rubinstein / 要旨: The AAA+ (ATPases associated with a variety of cellular activities) enzymes play critical roles in a variety of homeostatic processes in all kingdoms of life. Valosin-containing protein-like ATPase ...The AAA+ (ATPases associated with a variety of cellular activities) enzymes play critical roles in a variety of homeostatic processes in all kingdoms of life. Valosin-containing protein-like ATPase of Thermoplasma acidophilum (VAT), the archaeal homolog of the ubiquitous AAA+ protein Cdc48/p97, functions in concert with the 20S proteasome by unfolding substrates and passing them on for degradation. Here, we present electron cryomicroscopy (cryo-EM) maps showing that VAT undergoes large conformational rearrangements during its ATP hydrolysis cycle that differ dramatically from the conformational states observed for Cdc48/p97. We validate key features of the model with biochemical and solution methyl-transverse relaxation optimized spectroscopY (TROSY) NMR experiments and suggest a mechanism for coupling the energy of nucleotide hydrolysis to substrate unfolding. These findings illustrate the unique complementarity between cryo-EM and solution NMR for studies of molecular machines, showing that the structural properties of VAT, as well as the population distributions of conformers, are similar in the frozen specimens used for cryo-EM and in the solution phase where NMR spectra are recorded.
SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "EA" IN EACH CHAIN ON SHEET RECORDS BELOW ... SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "EA" IN EACH CHAIN ON SHEET RECORDS BELOW IS ACTUALLY AN 6-STRANDED BARREL THIS IS REPRESENTED BY A 7-STRANDED SHEET IN WHICH THE FIRST AND LAST STRANDS ARE IDENTICAL.
名称: 50 MM HEPES, 100 MM NACL, 5MM ADP / pH: 7.5 / 詳細: 50 MM HEPES, 100 MM NACL, 5MM ADP
試料
濃度: 7 mg/ml / 包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES
試料支持
詳細: HOLEY CARBON
急速凍結
装置: FEI VITROBOT MARK III / 凍結剤: ETHANE-PROPANE 詳細: VITRIFICATION 1 -- CRYOGEN- ETHANE-PROPANE MIXTURE, HUMIDITY- 100, INSTRUMENT- FEI VITROBOT MARK III, METHOD- BLOT FOR 4 SECONDS BEFORE PLUNGING, DETAILS- SAMPLE HELD AT 4 DEGREES CELSIUS BEFORE FREEZING
モード: BRIGHT FIELD / 倍率(公称値): 25000 X / 倍率(補正後): 34483 X / 最大 デフォーカス(公称値): 3500 nm / 最小 デフォーカス(公称値): 1800 nm / Cs: 2 mm
撮影
電子線照射量: 32 e/Å2 フィルム・検出器のモデル: GATAN K2 SUMMIT (4k x 4k)
画像スキャン
デジタル画像の数: 912
-
解析
EMソフトウェア
名称: RELION / カテゴリ: 3次元再構成
CTF補正
詳細: EACH MICROGRAPH
対称性
点対称性: C1 (非対称)
3次元再構成
解像度: 7 Å / 粒子像の数: 71258 / ピクセルサイズ(公称値): 1.45 Å / ピクセルサイズ(実測値): 1.45 Å / 倍率補正: CRYSTAL LATTICE MEASURMENT 詳細: HOMOLOGY MODEL WAS FLEXIBLY FIT INTO DENSITY, THEN STEREO- CHEMICALLY REFINED SUBMISSION BASED ON EXPERIMENTAL DATA FROM EMDB EMD-3436. (DEPOSITION ID: 14486). 対称性のタイプ: POINT
原子モデル構築
プロトコル: FLEXIBLE FIT / 空間: REAL 詳細: METHOD--MOLECULAR DYNAMICS FLEXIBLE FITTING REFINEMENT PROTOCOL--EM