1] Department of Physiology and Biophysics, University of California at Irvine, Irvine, California, USA. [2] [3].
1] Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark. [2] [3].
Nat Struct Mol Biol. 2014 Jan;21(1):43-8. doi: 10.1038/nsmb.2721. Epub 2013 Dec 8.
Heavy metals in cells are typically regulated by PIB-type ATPases. The first structure of the class, a Cu(+)-ATPase from Legionella pneumophila (LpCopA), outlined a copper transport pathway across the membrane, which was inferred to be occluded. Here we show by molecular dynamics simulations that extracellular water solvated the transmembrane (TM) domain, results indicative of a Cu(+)-release pathway. Furthermore, a new LpCopA crystal structure determined at 2.8-Å resolution, trapped in the preceding E2P state, delineated the same passage, and site-directed-mutagenesis activity assays support a functional role for the conduit. The structural similarities between the TM domains of the two conformations suggest that Cu(+)-ATPases couple dephosphorylation and ion extrusion differently than do the well-characterized PII-type ATPases. The ion pathway explains why certain Menkes' and Wilson's disease mutations impair protein function and points to a site for inhibitors targeting pathogens.
细胞中的重金属通常由 PIB 型 ATP 酶调节。该类别的第一个结构是来自军团菌属（Legionella pneumophila）的 Cu(+)-ATPase（LpCopA），它概述了跨膜的铜转运途径，该途径被推断为被阻塞。在这里，我们通过分子动力学模拟表明，细胞外水可溶解跨膜（TM）结构域，这表明存在 Cu(+)-释放途径。此外，通过 2.8-Å 分辨率确定的新的 LpCopA 晶体结构处于 E2P 状态之前，描绘了相同的通道，并且定点诱变活性测定支持该通道的功能作用。两种构象的 TM 结构域之间的结构相似性表明，Cu(+)-ATP 酶的去磷酸化和离子外排与特征明确的 PII 型 ATP 酶不同。离子途径解释了为什么某些 Menkes 和 Wilson 病突变会损害蛋白质功能，并指出了针对病原体的抑制剂的作用位点。
