ジャーナル: J Mol Biol / 年: 2014 タイトル: 3D cryo-electron reconstruction of BmrA, a bacterial multidrug ABC transporter in an inward-facing conformation and in a lipidic environment. 著者: Pierre Frederic Fribourg / Mohamed Chami / Carlos Oscar S Sorzano / Francesca Gubellini / Roberto Marabini / Sergio Marco / Jean-Michel Jault / Daniel Lévy / 要旨: ABC (ATP-binding cassette) membrane exporters are efflux transporters of a wide diversity of molecule across the membrane at the expense of ATP. A key issue regarding their catalytic cycle is whether ...ABC (ATP-binding cassette) membrane exporters are efflux transporters of a wide diversity of molecule across the membrane at the expense of ATP. A key issue regarding their catalytic cycle is whether or not their nucleotide-binding domains (NBDs) are physically disengaged in the resting state. To settle this controversy, we obtained structural data on BmrA, a bacterial multidrug homodimeric ABC transporter, in a membrane-embedded state. BmrA in the apostate was reconstituted in lipid bilayers forming a mixture of ring-shaped structures of 24 or 39 homodimers. Three-dimensional models of the ring-shaped structures of 24 or 39 homodimers were calculated at 2.3 nm and 2.5 nm resolution from cryo-electron microscopy, respectively. In these structures, BmrA adopts an inward-facing open conformation similar to that found in mouse P-glycoprotein structure with the NBDs separated by 3 nm. Both lipidic leaflets delimiting the transmembrane domains of BmrA were clearly resolved. In planar membrane sheets, the NBDs were even more separated. BmrA in an ATP-bound conformation was determined from two-dimensional crystals grown in the presence of ATP and vanadate. A projection map calculated at 1.6 nm resolution shows an open outward-facing conformation. Overall, the data are consistent with a mechanism of drug transport involving large conformational changes of BmrA and show that a bacterial ABC exporter can adopt at least two open inward conformations in lipid membrane.
ダウンロード / ファイル: emd_5526.map.gz / 形式: CCP4 / 大きさ: 29.8 MB / タイプ: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES)
注釈
Reconstruction of BmrA into lipid bilayer. D13 symmetrized reconstruction. 39 homodimers are inserted.
ボクセルのサイズ
X=Y=Z: 2.5 Å
密度
表面レベル
登録者による: 0.016 / ムービー #1: 0.016
最小 - 最大
-0.03009361 - 0.04987804
平均 (標準偏差)
0.00066482 (±0.01053878)
対称性
空間群: 1
詳細
EMDB XML:
マップ形状
Axis order
X
Y
Z
Origin
0
0
0
サイズ
200
200
200
Spacing
200
200
200
セル
A=B=C: 500.0 Å α=β=γ: 90.0 °
CCP4マップ ヘッダ情報:
mode
Image stored as Reals
Å/pix. X/Y/Z
2.5
2.5
2.5
M x/y/z
200
200
200
origin x/y/z
0.000
0.000
0.000
length x/y/z
500.000
500.000
500.000
α/β/γ
90.000
90.000
90.000
start NX/NY/NZ
-50
29
166
NX/NY/NZ
106
122
134
MAP C/R/S
1
2
3
start NC/NR/NS
0
0
0
NC/NR/NS
200
200
200
D min/max/mean
-0.030
0.050
0.001
-
添付データ
-
試料の構成要素
-
全体 : BmrA reconstituted at high density into lipid bilayer.
全体
名称: BmrA reconstituted at high density into lipid bilayer.
要素
試料: BmrA reconstituted at high density into lipid bilayer.
タンパク質・ペプチド: BmrA
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超分子 #1000: BmrA reconstituted at high density into lipid bilayer.
超分子
名称: BmrA reconstituted at high density into lipid bilayer. タイプ: sample / ID: 1000 集合状態: 39 Homodimers of BmrA inserted into lipid bilayer Number unique components: 1