Stable binding of the herpes simplex virus ICP47 protein to the peptide binding site of TAP
Stable binding of the herpes simplex virus ICP47 protein to the peptide binding site of TAP
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DOI：
10.1002/j.1460-2075.1996.tb00690.x
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发表时间：
1996-07-01
期刊：
影响因子：
11.4
通讯作者：
Johnson, DC
中科院分区：
文献类型：
--
作者：
Tomazin, R;Hill, AB;Johnson, DC
单纯疱疹病毒（HSV） ICP47蛋白通过抑制与抗原呈递相关的转运蛋白（TAP）来抑制MHC I类抗原呈递途径，TAP可使肽在内质网膜上易位。目前，ICP47是唯一的TAP抑制剂。在这里，我们发现细菌中产生的ICP47可以阻断人的TAP，而不是小鼠的TAP，并且ICP47的热变性对其阻断TAP的能力没有影响。ICP47抑制肽与TAP的结合，但不影响ATP的结合，这与之前的观察结果一致，即TAP的肽结合位点和ATP结合位点不同。与肽相比，ICP47以更高的亲和力（K-D类似于5 × 10(-8) M）与TAP结合，并且ICP47不会与TAP分离。ICP47不通过TAP运输，对细胞膜细胞质表面添加的蛋白酶保持敏感。多肽作为ICP47与TAP结合的竞争性抑制剂，这种抑制需要100到1000倍的多肽摩尔过量。这些结果表明，ICP47与一个包含TAP肽结合域的位点结合，并以稳定的方式保持与该位点的结合。
The herpes simplex virus (HSV) ICP47 protein inhibits the MHC class I antigen presentation pathway by inhibiting the transporter associated with antigen presentation (TAP) which translocates peptides across the endoplasmic reticulum membrane. At present, ICP47 is the only inhibitor of TAP. Here, we show that ICP47 produced in bacteria can block human, but not mouse, TAP, and that heat denaturation of ICP47 has no effect on its ability to block TAP. ICP47 inhibited peptide binding to TAP without affecting ATP binding, consistent with previous observations that the peptide binding and ATP binding sites of TAP are distinct. ICP47 bound to TAP with a higher affinity (K-D similar to 5X 10(-8) M) than did peptides, and ICP47 did not dissociate from TAP. ICP47 was not transported by TAP and remained sensitive to proteases added from the cytosolic surface of the membrane. Peptides acted as competitive inhibitors of ICP47 binding to TAP, and this inhibition required a 100- to 1000-fold molar excess of peptide. These results demonstrate that ICP47 binds to a site which includes the peptide binding domain of TAP and remains bound to this site in a stable fashion.