A conditional mutation affecting localization of the Menkes disease copper ATPase - Suppression by copper supplementation
A conditional mutation affecting localization of the Menkes disease copper ATPase - Suppression by copper supplementation
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DOI：
10.1074/jbc.m208737200
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发表时间：
2002-11-15
影响因子：
4.8
通讯作者：
Petris, MJ
中科院分区：
文献类型：
--
作者：
Kim, BE;Smith, K;Petris, MJ
铜是几个关键代谢过程的重要辅助因子。人类的这一需求被Menkes病所强调，Menkes病是一种由铜转运P型ATP酶MNK突变引起的X连锁铜缺乏症。MNK位于trans-Golgi网络中，在那里它将铜转运到分泌的铜酶。铜浓度的增加刺激MNK向质膜的运输，在那里它流出铜。在这项研究中，门克斯病突变，G1019 D，位于大的细胞质环的MNK，其特征在于在转染培养细胞。在铜限制条件下，G1019 D突变蛋白保留在内质网中。然而，通过向细胞中添加铜，这种错误定位得到了纠正，该过程依赖于MNK N-末端区域的铜结合位点。降低生长温度和化学伴侣，甘油，被发现纠正错误定位的G1019 D突变体，这表明这种突变干扰蛋白质折叠的分泌途径。这些发现将G1019 D确定为与Menkes病相关的第一个条件突变，并证明通过补充铜纠正了错误定位的蛋白质。我们的研究结果提供了一个分子框架，了解突变，影响门克斯患者的MNK转运蛋白的正确折叠可能是响应于肠外铜治疗。
Copper is an essential co-factor for several key metabolic processes. This requirement in humans is underscored by Menkes disease, an X-linked copper deficiency disorder caused by mutations in the copper transporting P-type ATPase, MNK. MNK is located in the trans-Golgi network where it transports copper to secreted cuproenzymes. Increases in copper concentration stimulate the trafficking of MNK to the plasma membrane where it effluxes copper. In this study, a Menkes disease mutation, G1019D, located in the large cytoplasmic loop of MNK, was characterized in transfected cultured cells. In copper-limiting conditions the G1019D mutant protein was retained in the endoplasmic reticulum. However, this mislocalization was corrected by the addition of copper to cells via a process that was dependent upon the copper binding sites at the N-terminal region of MNK. Reduced growth temperature and the chemical chaperone, glycerol, were found to correct the mislocalization of the G1019D mutant, suggesting this mutation interferes with protein folding in the secretory pathway. These findings identify G1019D as the first conditional mutation associated with Menkes disease and demonstrate correction of the mislocalized protein by copper supplementation. Our findings provide a molecular framework for understanding how mutations that affect the proper folding of the MNK transporter in Menkes patients may be responsive to parenteral copper therapy.