Weill Medical College, Cornell University, New York, NY 10021, USA.
Mol Cell. 2010 Apr 9;38(1):101-13. doi: 10.1016/j.molcel.2010.03.009.
TRAF1/2 and cIAP1/2 are members of the TNF receptor-associated factor (TRAF) and the inhibitor of apoptosis (IAP) families, respectively. They are critical for canonical and noncanonical NF-kappaB signaling pathways. Here, we report the crystal structures of the TRAF2: cIAP2 and the TRAF1: TRAF2: cIAP2 complexes. A TRAF2 trimer interacts with one cIAP2 both in the crystal and in solution. Two chains of the TRAF2 trimer directly contact cIAP2, and key residues at the interface are confirmed by mutagenesis. TRAF1 and TRAF2 preferentially form the TRAF1: (TRAF2)(2) heterotrimer, which interacts with cIAP2 more strongly than TRAF2 alone. In contrast, TRAF1 alone interacts very weakly with cIAP2. Surprisingly, TRAF1 and one chain of TRAF2 in the TRAF1: (TRAF2)(2): cIAP2 ternary complex mediate interaction with cIAP2. Because TRAF1 is upregulated by many stimuli, it may modulate the interaction of TRAF2 with cIAP1/2, which explains regulatory roles of TRAF1 in TNF signaling.
TRAF1/2 和 cIAP1/2 分别是肿瘤坏死因子受体相关因子(TRAF)和凋亡抑制蛋白(IAP)家族的成员。它们对于经典和非经典 NF-κB 信号通路至关重要。在这里,我们报告了 TRAF2:cIAP2 和 TRAF1:TRAF2:cIAP2 复合物的晶体结构。在晶体和溶液中,TRAF2 三聚体与一个 cIAP2 相互作用。TRAF2 三聚体的两条链直接与 cIAP2 接触,并且通过突变确认了界面上的关键残基。TRAF1 和 TRAF2 优先形成 TRAF1:(TRAF2)(2)异三聚体,与 cIAP2 的相互作用比 TRAF2 单独与 cIAP2 的相互作用更强。相比之下,TRAF1 单独与 cIAP2 的相互作用非常弱。令人惊讶的是,TRAF1 和 TRAF1:(TRAF2)(2):cIAP2 三元复合物中的 TRAF2 链介导与 cIAP2 的相互作用。由于 TRAF1 被许多刺激物上调,它可能调节 TRAF2 与 cIAP1/2 的相互作用,这解释了 TRAF1 在 TNF 信号中的调节作用。