- EMDB-21357: Structure of a bacterial Atm1-family ABC exporter -
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基本情報
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データベース: EMDB / ID: EMD-21357
タイトル
Structure of a bacterial Atm1-family ABC exporter
マップデータ
試料
複合体: homodimeric Atm1-type heavy metal transporter
タンパク質・ペプチド: ATM1-type heavy metal exporter
キーワード
ABC transporter / membrane protein / TRANSPORT PROTEIN
機能・相同性
機能・相同性情報
トランスロカーゼ / response to mercury ion / ABC-type transporter activity / monoatomic ion transport / ATP hydrolysis activity / ATP binding / plasma membrane 類似検索 - 分子機能
Type 1 protein exporter / ABC transporter transmembrane region / ABC transporter type 1, transmembrane domain / ABC transporter integral membrane type-1 fused domain profile. / ABC transporter type 1, transmembrane domain superfamily / ABC transporter-like, conserved site / ABC transporters family signature. / ABC transporter / ABC transporter-like, ATP-binding domain / ATP-binding cassette, ABC transporter-type domain profile. ...Type 1 protein exporter / ABC transporter transmembrane region / ABC transporter type 1, transmembrane domain / ABC transporter integral membrane type-1 fused domain profile. / ABC transporter type 1, transmembrane domain superfamily / ABC transporter-like, conserved site / ABC transporters family signature. / ABC transporter / ABC transporter-like, ATP-binding domain / ATP-binding cassette, ABC transporter-type domain profile. / ATPases associated with a variety of cellular activities / AAA+ ATPase domain / P-loop containing nucleoside triphosphate hydrolase 類似検索 - ドメイン・相同性
ジャーナル: Proc Natl Acad Sci U S A / 年: 2020 タイトル: A structural framework for unidirectional transport by a bacterial ABC exporter. 著者: Chengcheng Fan / Jens T Kaiser / Douglas C Rees / 要旨: The ATP-binding cassette (ABC) transporter of mitochondria (Atm1) mediates iron homeostasis in eukaryotes, while the prokaryotic homolog from (Atm1) can export glutathione derivatives and confer ...The ATP-binding cassette (ABC) transporter of mitochondria (Atm1) mediates iron homeostasis in eukaryotes, while the prokaryotic homolog from (Atm1) can export glutathione derivatives and confer protection against heavy-metal toxicity. To establish the structural framework underlying the Atm1 transport mechanism, we determined eight structures by X-ray crystallography and single-particle cryo-electron microscopy in distinct conformational states, stabilized by individual disulfide crosslinks and nucleotides. As Atm1 progresses through the transport cycle, conformational changes in transmembrane helix 6 (TM6) alter the glutathione-binding site and the associated substrate-binding cavity. Significantly, kinking of TM6 in the post-ATP hydrolysis state stabilized by MgADPVO eliminates this cavity, precluding uptake of glutathione derivatives. The presence of this cavity during the transition from the inward-facing to outward-facing conformational states, and its absence in the reverse direction, thereby provide an elegant and conceptually simple mechanism for enforcing the export directionality of transport by Atm1. One of the disulfide crosslinked Atm1 variants characterized in this work retains significant glutathione transport activity, suggesting that ATP hydrolysis and substrate transport by Atm1 may involve a limited set of conformational states with minimal separation of the nucleotide-binding domains in the inward-facing conformation.