High-affinity interactions of tumor necrosis factor receptor-associated factors (TRAFs) and CD40 require TRAF trimerization and CD40 multimerization
High-affinity interactions of tumor necrosis factor receptor-associated factors (TRAFs) and CD40 require TRAF trimerization and CD40 multimerization
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DOI：
10.1021/bi9909905
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发表时间：
1999-08-03
期刊：
影响因子：
2.9
通讯作者：
Kehry, MR
中科院分区：
文献类型：
--
作者：
Pullen, SS;Labadia, ME;Kehry, MR
一些 TNF 受体家族成员（包括 CD40）的信号传导是由 TNF 受体相关因子 (TDAF) 介导的，这些因子在配体诱导的受体寡聚化后与受体胞质结构域相互作用。在这里，我们定义了直接与 CD40 相互作用的重组 TRAF 结构域的寡聚结构，并定量了 TRAF2 和 TRAF3 对 CD40 的亲和力。生化和生物物理分析表明，TRAF1、TRAF2、TRAF3 和 TRAF6 的 TRAF 结构域在溶液中形成同源三聚体。 TRAF2 和 TRAF3 的 N 端缺失定义了三聚体形成所需的最小氨基酸序列，并表明卷曲螺旋 TRAF-N 区域是三聚化所必需的。与 TRAF 三聚化是与 CD40 的高亲和力相互作用所必需的想法一致，单体 TRAF-C 结构域与 CD40 的结合明显弱于三聚体 TRAF。在表面等离子共振研究中，发现三聚体TRAF对三聚体CD40的亲和力等级为TRAF2 > TRAF3，远大于TRAF1和TRAF6。 CD40 三聚化已被证明足以通过野生型 CD40 实现最佳 NF-κ B 和 p38 丝裂原激活蛋白激酶激活。相比之下，表达仅通过 TRAF6 信号传导的突变 CD40 (T254A) 的细胞系中，为了实现最大信号传导，需要更高程度的 CD40 多聚化。 TRAF 蛋白对寡聚受体的亲和力以及对受体多聚化程度的不同要求似乎有助于 TRAF 募集到受体细胞质结构域的选择性。
Signaling by some TNF receptor family members, including CD40, is mediated by TNF receptor-associated factors (TDAFs) that interact with receptor cytoplasmic domains following ligand- induced receptor oligomerization. Here we have defined the oligomeric structure of recombinant TRAF domains that directly interact with CD40 and quantitated the affinities of TRAF2 and TRAF3 for CD40. Biochemical and biophysical analyses demonstrated that TRAF domains of TRAF1, TRAF2, TRAF3, and TRAF6 formed homo-trimers in solution. N-terminal deletions of TRAF2 and TRAF3 defined minimal amino acid sequences necessary for trimer formation and indicated that the coiled coil TRAF-N region is required for trimerization. Consistent with the idea that TRAF trimerization is required for high-affinity interactions with CD40, monomeric TRAF-C domains bound to CD40 significantly weaker than trimeric TRAFs. In surface plasmon resonance studies, a hierarchy of affinity of trimeric TRAFs for trimeric CD40 was found to be TRAF2 > TRAF3 much greater than TRAF1 and TRAF6. CD40 trimerization was demonstrated to be sufficient for optimal NF-kappa B and p38 mitogen activated protein kinase activation through wild-type CD40. In contrast, a higher degree of CD40 multimerization was necessary for maximal signaling in a cell line expressing a mutated CD40 (T254A) that signaled only through TRAF6. The affinities of TRAF proteins for oligomerized receptors as well as different requirements for degree of receptor multimerization appear to contribute to the selectivity of TRAF recruitment to receptor cytoplasmic domains.