Functional analysis of genetic mutations in nucleotide binding domain 2 of the human retina specific ABC transporter
Functional analysis of genetic mutations in nucleotide binding domain 2 of the human retina specific ABC transporter
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DOI：
10.1021/bi034481l
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发表时间：
2003-09-16
期刊：
影响因子：
2.9
通讯作者：
Biswas-Fiss, EE
中科院分区：
文献类型：
--
作者：
Biswas-Fiss, EE
视杆细胞外段（ROS）ABC转运蛋白（ABCR）在视网膜视杆细胞外段中起重要作用，在视杆细胞外段中，其作为全反式视黄酸的转运蛋白起作用，最可能作为复合脂质，视黄亚基-磷脂酰-乙醇胺。我们在这里报告的结构和功能的影响，与几个黄斑变性，在第二个核苷酸结合域的ABCR（NBD 2）的基因突变的定量分析。我们分析了ATP结合，ATP水解动力学和结构变化。这些多方面分析的结果与疾病的严重程度和预后相关。这里呈现的结果表明，在野生型NBD 2中，不同的构象变化伴随核苷酸（ATP和ADP）结合。在ATP结合后，NBD 2蛋白改变为松弛构象，在该松弛构象中，NBD 2蛋白变得更加暴露于溶剂，而ADP结合逆转了该过程，并导致回到未结合蛋白也观察到的拉紧构象。这一序列的构象变化似乎是重要的能量的ATP水解，并可能有重要的结构后果的能力的NBD 2域作为一个调节器的核苷酸结合域1。一些突变体蛋白质显示出显着不同的模式的构象变化后，核苷酸结合，这些基因突变的独特结构的后果。与各种视网膜病相关的ABCR功能障碍本质上是多方面的，包括蛋白质结构的改变以及ATP酶活性和核苷酸结合的减弱。
The rod outer segment (ROS) ABC transporter (ABCR) plays an important role in the outer segment of retinal rod cells, where it functions as a transporter of all-trans retinal, most probably as the complex lipid, retinylidene-phosphatidyl-ethanolamine. We report here a quantitative analysis of the structural and functional effects of genetic mutations, associated with several macular degenerations, in the second nucleotide-binding domain of ABCR (NBD2). We have analyzed the ATP binding, kinetics of ATP hydrolysis, and structural changes. The results of these multifaceted analyses were correlated with the disease severity and prognosis. Results presented here demonstrated that, in wild type NBD2, distinct conformational changes accompany nucleotide (ATP and ADP) binding. Upon ATP binding, NBD2 protein changed to a relaxed conformation where tryptophans became more solvent-exposed, while ADP binding reverses this process and leads back to a taut conformation that is also observed with the unbound protein. This sequence of conformational change appears to be important in the energetics of the ATP hydrolysis and may have important structural consequences in the ability of the NBD2 domain to act as a regulator of the nucleotide-binding domain 1. Some of the mutant proteins displayed strikingly different patterns of conformational changes upon nucleotide binding that pointed to unique structural consequences of these genetic mutations. The ABCR dysfunctions, associated with various retinopathies, are multifaceted in nature and include alterations in protein structure as well as the attenuation of ATPase activity and nucleotide binding.