An Annular Lipid Belt Is Essential for Allosteric Coupling and Viral Inhibition of the Antigen Translocation Complex TAP (Transporter Associated with Antigen Processing)
An Annular Lipid Belt Is Essential for Allosteric Coupling and Viral Inhibition of the Antigen Translocation Complex TAP (Transporter Associated with Antigen Processing)
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DOI：
10.1074/jbc.m114.592832
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发表时间：
2014-11-28
影响因子：
4.8
通讯作者：
Tampe, Robert
中科院分区：
文献类型：
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作者：
Eggensperger, Sabine;Fisette, Olivier;Tampe, Robert
与抗原加工相关的转运蛋白（TAP）构成了针对感染或恶性转化细胞的适应性免疫应答中的焦点元件。TAP穿梭蛋白酶体降解产物进入内质网的内腔，用于装载主要组织相容性复合体（MHC）I类分子。在此，将异二聚体TAP复合物纯化并以限定的化学计量在纳米盘中重构。我们证明，一个单一的异源二聚体核心TAP复合物是积极的肽结合，这是紧密耦合到ATP水解。值得注意的是，随着肽长度的增加，ATP周转率逐渐降低，这表明ATP水解通过ATP结合盒转运蛋白与肽的运动偶联。此外，全原子分子动力学模拟表明，所观察到的22个脂质足以形成一个环形带周围的TAP复合物。该脂质带对于疱疹病毒免疫evasin ICP47的高亲和力抑制是必需的。总之，纳米盘是研究脂质的重要作用以及抗原易位机制的功能、相互作用和调节的有力方法。
The transporter associated with antigen processing (TAP) constitutes a focal element in the adaptive immune response against infected or malignantly transformed cells. TAP shuttles proteasomal degradation products into the lumen of the endoplasmic reticulum for loading of major histocompatibility complex (MHC) class I molecules. Here, the heterodimeric TAP complex was purified and reconstituted in nanodiscs in defined stoichiometry. We demonstrate that a single heterodimeric core-TAP complex is active in peptide binding, which is tightly coupled to ATP hydrolysis. Notably, with increasing peptide length, the ATP turnover was gradually decreased, revealing that ATP hydrolysis is coupled to the movement of peptide through the ATP-binding cassette transporter. In addition, all-atom molecular dynamics simulations show that the observed 22 lipids are sufficient to form an annular belt surrounding the TAP complex. This lipid belt is essential for high affinity inhibition by the herpesvirus immune evasin ICP47. In conclusion, nanodiscs are a powerful approach to study the important role of lipids as well as the function, interaction, and modulation of the antigen translocation machinery.