State Key Laboratory for Agrobiotechnology, Department of Nutrition and Health, College of Biological Sciences, China Agricultural University, Beijing, China.
Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
Elife. 2022 Nov 14;11:e75039. doi: 10.7554/eLife.75039.
Adrenoleukodystrophy protein (ALDP) is responsible for the transport of very-long-chain fatty acids (VLCFAs) and corresponding CoA-esters across the peroxisomal membrane. Dysfunction of ALDP leads to peroxisomal metabolic disorder exemplified by X-linked adrenoleukodystrophy (ALD). Hundreds of ALD-causing mutations have been identified on ALDP. However, the pathogenic mechanisms of these mutations are restricted to clinical description due to limited structural and biochemical characterization. Here we report the cryo-electron microscopy structure of human ALDP with nominal resolution at 3.4 Å. ALDP exhibits a cytosolic-facing conformation. Compared to other lipid ATP-binding cassette transporters, ALDP has two substrate binding cavities formed by the transmembrane domains. Such structural organization may be suitable for the coordination of VLCFAs. Based on the structure, we performed integrative analysis of the cellular trafficking, protein thermostability, ATP hydrolysis, and the transport activity of representative mutations. These results provide a framework for understanding the working mechanism of ALDP and pathogenic roles of disease-associated mutations.
肾上腺脑白质营养不良蛋白（ALDP）负责将超长链脂肪酸（VLCFAs）及其相应的 CoA 酯转运穿过过氧化物酶体膜。ALDP 功能障碍导致过氧化物酶体代谢紊乱，表现为 X 连锁肾上腺脑白质营养不良（ALD）。已经在 ALDP 上鉴定出数百种导致 ALD 的突变。然而，由于结构和生化特征有限，这些突变的致病机制仅限于临床描述。在这里，我们报告了人类 ALDP 的冷冻电子显微镜结构，其名义分辨率为 3.4 Å。ALDP 呈现出面向细胞质的构象。与其他脂质 ATP 结合盒转运蛋白相比，ALDP 由跨膜结构域形成两个底物结合腔。这种结构组织可能适合于 VLCFAs 的协调。基于该结构，我们对代表性突变体的细胞运输、蛋白质热稳定性、ATP 水解和转运活性进行了综合分析。这些结果为理解 ALDP 的工作机制和疾病相关突变的致病作用提供了框架。
