New Structural Arrangement of the Extracellular Regions of the Phosphate Transporter SLC20A1, the Receptor for Gibbon Ape Leukemia Virus
New Structural Arrangement of the Extracellular Regions of the Phosphate Transporter SLC20A1, the Receptor for Gibbon Ape Leukemia Virus
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DOI：
10.1074/jbc.m109.022566
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发表时间：
2009-10-23
影响因子：
4.8
通讯作者：
Eiden, Maribeth V.
中科院分区：
文献类型：
--
作者：
Farrell, Karen B.;Tusnady, Gabor E.;Eiden, Maribeth V.
逆转录病毒感染宿主细胞需要与细胞受体的初始相互作用。对于许多γ逆转录病毒，如长臂猿白血病病毒、毛猴病毒、猫白血病病毒亚组B、猫白血病病毒亚组T和10 A1鼠白血病病毒，这种受体是人III型钠依赖性无机磷酸盐转运蛋白SLC 20 A1，以前称为PiT 1。了解关键的受体功能和与病毒的相互作用，导致成功感染，需要我们首先知道细胞受体的表面结构。以前的分子模型从蛋白质序列，有限的经验数据，预测蛋白质与10个跨膜螺旋。在这里，我们进行了取代半胱氨酸可及性诱变的生化方法来解决这个受体在活细胞中的拓扑结构。我们发现蛋白质的某些片段出乎意料地暴露在外界环境中。通过使用取代的半胱氨酸可及性诱变确定的信息设置HMTOP，隐马尔可夫模型为基础的跨膜拓扑预测方法的约束，我们现在提出了一个全面的拓扑模型SLC20A1，一个跨膜蛋白与12个跨膜螺旋和7个胞外区，从以前的模型不同，应该允许的方法，定义病毒相互作用和运输功能。
Infection of a host cell by a retrovirus requires an initial interaction with a cellular receptor. For numerous gammaretroviruses, such as the gibbon ape leukemia virus, woolly monkey virus, feline leukemia virus subgroup B, feline leukemia virus subgroup T, and 10A1 murine leukemia virus, this receptor is the human type III sodium-dependent inorganic phosphate transporter, SLC20A1, formerly known as PiT1. Understanding the critical receptor functionalities and interactions with the virus that lead to successful infection requires that we first know the surface structure of the cellular receptor. Previous molecular modeling from the protein sequence, and limited empirical data, predicted a protein with 10 transmembrane helices. Here we undertake the biochemical approach of substituted cysteine accessibility mutagenesis to resolve the topology of this receptor in live cells. We discover that there are segments of the protein that are unexpectedly exposed to the outside milieu. By using information determined by substituted cysteine accessibility mutagenesis to set constraints in HMMTOP, a hidden Markov model-based transmembrane topology prediction method, we now propose a comprehensive topological model for SLC20A1, a transmembrane protein with 12 transmembrane helices and 7 extracellular regions, that varies from previous models and should permit approaches that define both virus interaction and transport function.