ジャーナル: Nat Commun / 年: 2021 タイトル: Structures of ABCG2 under turnover conditions reveal a key step in the drug transport mechanism. 著者: Qin Yu / Dongchun Ni / Julia Kowal / Ioannis Manolaridis / Scott M Jackson / Henning Stahlberg / Kaspar P Locher / 要旨: ABCG2 is a multidrug transporter that affects drug pharmacokinetics and contributes to multidrug resistance of cancer cells. In previously reported structures, the reaction cycle was halted by the ...ABCG2 is a multidrug transporter that affects drug pharmacokinetics and contributes to multidrug resistance of cancer cells. In previously reported structures, the reaction cycle was halted by the absence of substrates or ATP, mutation of catalytic residues, or the presence of small-molecule inhibitors or inhibitory antibodies. Here we present cryo-EM structures of ABCG2 under turnover conditions containing either the endogenous substrate estrone-3-sulfate or the exogenous substrate topotecan. We find two distinct conformational states in which both the transport substrates and ATP are bound. Whereas the state turnover-1 features more widely separated NBDs and an accessible substrate cavity between the TMDs, turnover-2 features semi-closed NBDs and an almost fully occluded substrate cavity. Substrate size appears to control which turnover state is mainly populated. The conformational changes between turnover-1 and turnover-2 states reveal how ATP binding is linked to the closing of the cytoplasmic side of the TMDs. The transition from turnover-1 to turnover-2 is the likely bottleneck or rate-limiting step of the reaction cycle, where the discrimination of substrates and inhibitors occurs.
超分子 #1: ABCG2 in complex with topotecan under turnover condition
超分子
名称: ABCG2 in complex with topotecan under turnover condition タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: #1 詳細: ABCG2 was incubated with 5mM ATP, 5mM MgCl2, 0.5mM ADP, 100 uM topotecan at room temperature for 10 min