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Structure of an ABC transporter in complex with its binding protein

机译:ABC转运蛋白及其结合蛋白复合物的结构

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摘要

ATP-binding cassette (ABC) transporter proteins carry diverse substrates across cell membranes. Whereas clinically relevant ABC exporters are implicated in various diseases or cause multi-drug resistance of cancer cells, bacterial ABC importers are essential for the uptake of nutrients, including rare elements such as molybdenum. A detailed understanding of their mechanisms requires direct visualization at high resolution and in distinct conformations. Our recent structure of the multidrug ABC exporter Sav1866 has revealed an outward-facing conformation of the transmembrane domains coupled to a closed conformation of the nucleotide-binding domains, reflecting the ATP-bound state. Here we present the 3.1 A crystal structure of a putative molybdate transporter (ModB_2C_2) from Archaeoglobus fulgidus in complex with its binding protein (ModA). Twelve transmembrane helices of the ModB subunits provide an inward-facing conformation, with a closed gate near the external membrane boundary. The ATP-hydrolysing ModC subunits reveal a nudeotide-free, open conformation, whereas the attached binding protein aligns the substrate-binding cleft with the entrance to the presumed trans-location pathway. Structural comparison of ModB_2C_2A with Sav1866 suggests a common alternating access and release mechanism, with binding of ATP promoting an outward-facing conformation and dissociation of the hydrolysis products promoting an inward-facing conformation.
机译:ATP结合盒(ABC)转运蛋白跨细胞膜携带多种底物。尽管临床上相关的ABC出口商牵涉多种疾病或引起癌细胞的多药耐药性,但细菌性ABC进口商对于摄取养分(包括稀有元素,例如钼)至关重要。对它们的机制的详细了解需要以高分辨率和不同的构型直接可视化。我们最近的多药ABC出口商Sav1866的结构揭示了跨膜结构域的向外构象与核苷酸结合结构域的闭合构象偶联,反映了ATP结合状态。在这里,我们介绍了古细菌古细菌的一个假定的钼酸盐转运蛋白(ModB_2C_2)的3.1 A晶体结构及其结合蛋白(ModA)的复合物。 ModB亚基的十二个跨膜螺旋提供了一个向内的构象,在外部膜边界附近有一个封闭的门。水解ATP的ModC亚基揭示了无核苷的开放构象,而附着的结合蛋白将底物结合裂口与假定的易位途径的入口对齐。 ModB_2C_2A与Sav1866的结构比较表明,共有的交替访问和释放机制,其中ATP的结合促进了向外构象,而水解产物的解离促进了向内构象。

著录项

  • 来源
    《Nature》 |2007年第7132期|p.213-216|共4页
  • 作者单位

    Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然科学总论;
  • 关键词

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