The role of apolipoprotein A-I helix 10 in apolipoprotein-mediated cholesterol efflux via the ATP-binding cassette transporter ABCA1
The role of apolipoprotein A-I helix 10 in apolipoprotein-mediated cholesterol efflux via the ATP-binding cassette transporter ABCA1
复制标题
DOI：
10.1074/jbc.m207005200
复制
发表时间：
2002-10-18
影响因子：
4.8
通讯作者：
Davidson, WS
中科院分区：
文献类型：
--
作者：
Panagotopulos, SE;Witting, SR;Davidson, WS
最近对丹吉尔病的研究表明，atp结合盒转运蛋白A1 (ABCA1)/载脂蛋白A-I （apoA-I）的相互作用对于高密度脂蛋白颗粒的形成、apoA-I的完整性和适当的逆向胆固醇运输至关重要。然而，这种相互作用的细节是未知的。有研究表明，apoa - 1的两亲螺旋与ABCA1转运体形成的脂质结构域结合。另外，apoa - 1也可能直接与ABCA1结合。为了更好地理解这种相互作用，我们创建了几个apoA-I的截断突变体，然后使用更具体的点突变体和螺旋易位突变体来识别和表征abca1介导的胆固醇外排所需的apoA-I的位置。我们发现残基221-243（螺旋10）的缺失可消除8-溴- camp处理的培养的RAW小鼠巨噬细胞中abca1介导的胆固醇外排。与野生型相比，影响螺旋电荷分布的螺旋10点突变减少了abca1介导的胆固醇外排。我们注意到，当螺旋10发生突变时，胆固醇外排与apoa - 1的脂质结合特性之间存在强烈的正相关。然而，只要螺旋10在C端保持完整，蛋白质其他区域的螺旋易位就没有这种相关性。根据这些观察，我们提出了载脂蛋白介导的外排的另一种模型。
Recent studies of Tangier disease have shown that the ATP-binding cassette transporter A1 (ABCA1)/apolipoprotein A-I (apoA-I) interaction is critical for high density lipoprotein particle formation, apoA-I integrity, and proper reverse cholesterol transport. However, the specifics of this interaction are unknown. It has been suggested that amphipathic helices of apoA-I bind to a lipid domain created by the ABCA1 transporter. Alternatively, apoA-I may bind directly to ABCA1 itself. To better understand this interaction, we created several truncation mutants of apoA-I and then followed up with more specific point mutants and helix translocation mutants to identify and characterize the locations of apoA-I required for ABCA1-mediated cholesterol efflux. We found that deletion of residues 221-243 (helix 10) abolished ABCA1-mediated cholesterol efflux from cultured RAW mouse macrophages treated with 8-bromo-cAMP. Point mutations in helix 10 that affected the helical charge distribution reduced ABCA1-mediated cholesterol efflux versus the wild type. We noted a strong positive correlation between cholesterol efflux and the lipid binding characteristics of apoA-I when mutations were made in helix 10. However, there was no such correlation for helix translocations in other areas of the protein as long as helix 10 remained intact at the C terminus. From these observations, we propose an alternative model for apolipoprotein-mediated efflux.