The tyrosine binding pocket in the adaptor protein 1 (AP-1) μ1 subunit is necessary for nef to recruit AP-1 to the major histocompatibility complex class I cytoplasmic tail
The tyrosine binding pocket in the adaptor protein 1 (AP-1) μ1 subunit is necessary for nef to recruit AP-1 to the major histocompatibility complex class I cytoplasmic tail
复制标题
DOI：
10.1074/jbc.m707760200
复制
发表时间：
2008-02-08
影响因子：
4.8
通讯作者：
Collins, Kathleen L.
中科院分区：
文献类型：
--
作者：
Wonderlich, Elizabeth R.;Williams, Maya;Collins, Kathleen L.
为了逃避抗人类免疫缺陷病毒（HIV）的免疫反应，HIV Nef蛋白通过招募网格蛋白适配蛋白1 （AP-1）到MHC-I的细胞质尾部，破坏主要的组织相容性复合体I类（MHC-I）的运输。在正常情况下，AP-1通过物理上分离的结合位点结合二亮氨酸和酪氨酸信号（YXX phi基序）。在Nef- MHC-I复合物的情况下，AP-1的结合绝对需要人白细胞抗原(HLA)- a2细胞质尾部的酪氨酸（(320)YSQA）和Nef中的蛋氨酸（Met(20)）。Nef中还存在二苯胺基序，它通常不影响MHC-I的转运，也不需要将AP-1招募到Nef- MHC-I复合物中。然而，有证据表明，这种二苯甲酸基序可以通过将Nef融合到顺式HLA-A2尾部而激活。因此，该基序无法在反式中发挥作用可能是由于Nef与MHC-I细胞质尾部结合时发生的结构变化。无论Nef是顺式还是反式存在，AP-1向mhc -1的酪氨酸依赖性募集都是由Nef内的酸性结构域和脯氨酸结构域稳定的。此外，HLA-A和HLA-C和HLA-E分子胞质尾部的氨基酸Ala（324）和Asp（327）也稳定了AP-1的结合。最后，AP-1的mu亚基酪氨酸结合袋的突变产生了Nef诱导的HLA-A2下调的显性阴性抑制剂，破坏了野生型AP-1与Nef- MHC-I复合物的结合。因此，这些数据证明Nef与MHC-I胞质尾部的结合稳定了MHC-I胞质尾部酪氨酸与AP-1中天然酪氨酸结合袋的相互作用。
To evade the anti-human immunodeficiency virus (HIV) immune response, the HIV Nef protein disrupts major histocompatibility complex class I (MHC-I) trafficking by recruiting the clathrin adaptor protein 1 (AP-1) to the MHC-I cytoplasmic tail. Under normal conditions AP-1 binds dileucine and tyrosine signals (YXX phi motifs) via physically separate binding sites. In the case of the Nef- MHC-I complex, a tyrosine in the human leukocyte antigen (HLA)-A2 cytoplasmic tail ((320)YSQA) and a methionine in Nef (Met(20)) are absolutely required for AP-1 binding. Also present in Nef is a dileucine motif, which does not normally affect MHC-I trafficking and is not needed to recruit AP-1 to the Nef- MHC-I-complex. However, evidence is presented here that this dileucine motif can be activated by fusing Nef to the HLA-A2 tail in cis. Thus, the inability of this motif to function in trans likely results from a structural change that occurs when Nef binds to the MHC-I cytoplasmic tail. The physiologically relevant tyrosine-dependent recruitment of AP-1 to MHC-I, which occurs whether Nef is present in cis or trans, was stabilized by the acidic and polyproline domains within Nef. Additionally, amino acids Ala(324) and Asp(327) in the cytoplasmic tails of HLA-A and (but not HLA-C and HLA-E) molecules also stabilized AP-1 binding. Finally, mutation of the tyrosine binding pocket in the mu subunit of AP-1 created a dominant negative inhibitor of Nef- induced down-modulation of HLA-A2 that disrupted binding of wild type AP-1 to the Nef- MHC-I complex. Thus, these data provide evidence that Nef binding to the MHC-I cytoplasmic tail stabilizes the interaction of a tyrosine in the MHC-I cytoplasmic tail with the natural tyrosine binding pocket in AP-1.