Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.
Biochemistry. 2023 Nov 7;62(21):3159-3165. doi: 10.1021/acs.biochem.3c00417. Epub 2023 Oct 9.
The ATP-binding cassette (ABC) transporter ABCB10 resides in the inner membrane of mitochondria and is implicated in erythropoiesis. Mitochondria from different cell types share some specific characteristics, one of which is the high abundance of cardiolipin. Although previous studies have provided insight into ABCB10, the affinity and selectivity of this transporter toward lipids, particularly those found in the mitochondria, remain poorly understood. Here, native mass spectrometry is used to directly monitor the binding events of lipids to human ABCB10. The results reveal that ABCB10 binds avidly to cardiolipin with an affinity significantly higher than that of other phospholipids. The first three binding events of cardiolipin display positive cooperativity, which is suggestive of specific cardiolipin-binding sites on ABCB10. Phosphatidic acid is the second-best binder of the lipids investigated. The bulk lipids, phosphatidylcholine and phosphatidylethanolamine, display the weakest binding affinity for ABCB10. Other lipids bind ABCB10 with a similar affinity. Functional assays show that cardiolipin regulates the ATPase activity of ABCB10 in a dose-dependent fashion. ATPase activity of ABCB10 was also impacted in the presence of other lipids but to a lesser extent than cardiolipin. Taken together, ABCB10 has a high binding affinity for cardiolipin, and this lipid also regulates the ATPase activity of the transporter.
ATP 结合盒（ABC）转运蛋白 ABCB10 位于线粒体的内膜中，与红细胞生成有关。不同细胞类型的线粒体具有一些共同的特征，其中之一是心磷脂的含量很高。尽管之前的研究已经深入了解了 ABCB10，但该转运蛋白对脂质的亲和力和选择性，特别是对线粒体中的脂质的亲和力和选择性，仍知之甚少。在这里，我们使用天然质谱法直接监测脂质与人类 ABCB10 的结合事件。结果表明，ABCB10 与心磷脂具有很强的亲和力，其亲和力明显高于其他磷脂。心磷脂的前三个结合事件显示出正协同性，这表明 ABCB10 上存在特定的心磷脂结合位点。在研究的脂质中，磷酸脂酸是第二好的结合剂。大量的脂质，磷脂酰胆碱和磷脂酰乙醇胺，对 ABCB10 的结合亲和力最弱。其他脂质与 ABCB10 的结合亲和力相似。功能测定表明，心磷脂以剂量依赖的方式调节 ABCB10 的 ATP 酶活性。在存在其他脂质的情况下，ABCB10 的 ATP 酶活性也受到影响，但程度小于心磷脂。综上所述，ABCB10 对心磷脂具有很高的亲和力，并且这种脂质还调节转运蛋白的 ATP 酶活性。
