Banci Lucia, Bertini Ivano, Cantini Francesca, Della-Malva Nunzia, Migliardi Manuele, Rosato Antonio
Magnetic Resonance Center, Via L. Sacconi 6, and Department of Chemistry, Via della Lastruccia 3, University of Florence, Italy.
J Biol Chem. 2007 Aug 10;282(32):23140-6. doi: 10.1074/jbc.M700695200. Epub 2007 Jun 2.
ATP7A is a P-type ATPase involved in copper(I) homeostasis in humans. It possesses a long N-terminal cytosolic tail containing six domains that are individually folded and capable of binding one copper(I) ion each. We investigated the entire N-terminal tail (MNK1-6) in solution by NMR spectroscopy and addressed its interaction with copper(I) and with copper(I)-HAH1, the physiological partner of ATP7A. At copper(I)-HAH1:MNK1-6 ratios of up to 3:1, thus encompassing the range of protein ratios in vivo, both the first and fourth domain of the tail formed a metal-mediated adduct with HAH1 whereas the sixth domain was simultaneously able to partly remove copper(I) from HAH1. These processes are not dependent on one another. In particular, formation of the adducts is not necessary for copper(I) transfer from HAH1 to the sixth domain. The present data, together with available in vivo studies, suggest that the localization of ATP7A between the trans-Golgi network and the plasma membrane may be regulated by the accumulation of the adducts with HAH1, whereas the main role of domains 5 and 6 is to assist copper(I) translocation.
ATP7A是一种参与人体铜（I）稳态的P型ATP酶。它具有一个长的N端胞质尾巴，包含六个结构域，这些结构域各自折叠，每个结构域能够结合一个铜（I）离子。我们通过核磁共振光谱研究了溶液中的整个N端尾巴（MNK1-6），并探讨了它与铜（I）以及与ATP7A的生理伴侣铜（I）-HAH1的相互作用。在铜（I）-HAH1与MNK1-6的比例高达3:1的情况下，涵盖了体内蛋白质比例的范围，尾巴的第一个和第四个结构域都与HAH1形成了金属介导的加合物，而第六个结构域同时能够部分地从HAH1中去除铜（I）。这些过程相互不依赖。特别是，加合物的形成对于铜（I）从HAH1转移到第六个结构域不是必需的。目前的数据，连同现有的体内研究，表明ATP7A在反式高尔基体网络和质膜之间的定位可能受与HAH1加合物积累的调节，而第5和第6结构域的主要作用是协助铜（I）转运。
