The core domain of chemokines binds CCR5 extracellular domains while their amino terminus interacts with the transmembrane helix bundle
The core domain of chemokines binds CCR5 extracellular domains while their amino terminus interacts with the transmembrane helix bundle
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DOI：
10.1074/jbc.m205684200
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发表时间：
2003-02-14
影响因子：
4.8
通讯作者：
Parmentier, M
中科院分区：
文献类型：
--
作者：
Blanpain, C;Doranz, BJ;Parmentier, M
CCR 5是多种炎性CC-趋化因子的功能性受体，包括巨噬细胞炎性蛋白（MIP）-1 α和RANTES（调节正常T细胞表达和分泌的活化），并且是人类免疫缺陷病毒的主要辅助受体。CCR 5的第二胞外环和氨基末端结构域对于趋化因子结合是至关重要的，而跨膜螺旋束参与受体活化。还鉴定了对CCR 5结合和/或活化重要的趋化因子结构域和残基。然而，趋化因子与CCR 5相互作用并激活CCR 5的确切方式目前尚不清楚。在这项研究中，我们比较了趋化因子变体与野生型CCR 5和CCR 5点突变体的结合和功能特性。CCR 5胞外结构域的几个突变（E172 A、R168 A、K191 A和D276 A）强烈影响MIP-1 α结合，但对RANTES结合几乎没有影响。然而，MIP/RANTES嵌合体，含有MIP-1 α N末端和RANTES核心，结合这些突变体的亲和力类似于RANTES。几种影响跨膜螺旋2和3的CCR 5突变体（L104 F、L104 F/F109 H/F112 Y、F85 L/L104 F）使MIP-1 α的效力降低10-100倍，而对RANTES的激活作用几乎没有影响。然而，MIP/RANTES嵌合体以与MIP-1 α相似的效力激活这些突变体。相反，LD 78 β，一种天然MIP-1 α变体，与RANTES一样，在2位含有脯氨酸，激活这些突变体以及RANTES。总之，这些结果表明MIP-1 α和RANTES的核心结构域结合CCR 5胞外结构域中的不同残基，而趋化因子的N末端通过与跨膜螺旋束相互作用介导受体活化。
CCR5 is a functional receptor for various inflammatory CC-chemokines, including macrophage inflammatory protein (MIP)-1alpha and RANTES (regulated on activation normal T cell expressed and secreted), and is the main coreceptor of human immunodeficiency viruses. The second extracellular loop and amino-terminal domain of CCR5 are critical for chemokine binding, whereas the transmembrane helix bundle is involved in receptor activation. Chemokine domains and residues important for CCR5 binding and/or activation have also been identified. However, the precise way by which chemokines interact with And activate CCR5 is presently unknown. In this study, we have compared the binding and functional properties of chemokine variants onto wild-type CCR5 and CCR5 point mutants. Several mutations in CCR5 extracellular domains (E172A, R168A, K191A, and D276A) strongly affected MIP-1alpha binding but had little effect on RANTES binding. However, a MIP/RANTES chimera, containing the MIP-1alpha N terminus and the RANTES core, bound to these mutants with an affinity similar to that of RANTES. Several CCR5 mutants affecting transmembrane helices 2 and 3 (L104F, L104F/F109H/F112Y, F85L/L104F) reduced the potency of MIP-1alpha by 10-100 fold with little effect on activation by RANTES. However, the MIP/RANTES chimera activated these mutants with a potency similar to that of MIP-1alpha. In contrast, LD78beta, a natural MIP-1alpha variant, which, like RANTES, contains a proline at position 2, activated these mutants as well as RANTES. Altogether, these results suggest that the core domains of MIP-1alpha and RANTES bind distinct residues in CCR5 extracellular domains, whereas the N terminus of chemokines mediates receptor activation by interacting with the transmembrane helix bundle.