Degradation of p53 by adenovirus E4orf6 and E1B55K proteins occurs via a novel mechanism, involving a Cullin-containing complex
Degradation of p53 by adenovirus E4orf6 and E1B55K proteins occurs via a novel mechanism, involving a Cullin-containing complex
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DOI：
10.1101/gad.926401
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发表时间：
2001-12-01
影响因子：
10.5
通讯作者：
Branton, PE
中科院分区：
文献类型：
--
作者：
Querido, E;Blanchette, P;Branton, PE
虽然MDM2在调节P53抑癌蛋白的稳定性方面发挥了重要作用，但也存在其他知之甚少的MDM2非依赖性通路。人类腺病毒已经进化出调控P53功能和稳定性的策略，以允许有效的病毒复制。一种机制涉及腺病毒E1B55K和E4orf6蛋白，它们协作靶向p53进行降解。为了确定这一过程的机制，我们纯化了一个与E4orf6相关的多蛋白复合体，并证明其包含一个新的包含cullin的E3泛素连接酶：(1)由cullin家族成员cul5、Elongins B和C以及环-H2指蛋白Rbx1(ROC1)组成；(2)与von Hippel-Lindau肿瘤抑制因子和SCF(Skp1-cul1/CDc53-F-box)E3泛素连接酶复合体非常相似；以及(3)在E1/E2泛素激活和结合酶的存在下，在体外能够刺激p53的泛素化。库林被NEDD8修饰激活；因此，为了确定腺病毒诱导的P53降解是否需要库林复合体，我们在对NEDD8途径温度敏感的TS41中国仓鼠卵巢细胞中进行了研究。在不允许的温度下，E4orf6/E1B55K不能诱导p53的降解。因此，我们的结果确定了基于cullin的机制在调控p53中的新角色。
Although MDM2 plays a major role in regulating the stability of the p53 tumor suppressor protein, other poorly understood MDM2-independent pathways also exist. Human adenoviruses have evolved strategies to regulate p53 function and stability to permit efficient viral replication. One mechanism involves adenovirus E1B55K and E4orf6 proteins, which collaborate to target p53 for, degradation. To determine the mechanism of this process, a multiprotein E4orf6-associated complex was purified and shown to contain a novel Cullin-containing E3 ubiquitin ligase that is (1) composed of Cullin family member Cul5, Elongins B and C, and the RING-H2 finger protein Rbx1(ROC1); (2) remarkably similar to the von Hippel-Lindau tumor suppressor and SCF (Skp1-Cul1/Cdc53-F-box) E3 ubiquitin ligase complexes; and (3) capable of stimulating ubiquitination of p53 in vitro in the presence of E1/E2 ubiquitin-activating and -conjugating enzymes. Cullins are activated by NEDD8 modification; therefore, to determine whether Cullin complexes are required for adenovirus-induced p53 degradation, studies were conducted in ts41 Chinese hamster ovary cells that are temperature sensitive for the NEDD8 pathway. E4orf6/E1B55K failed to induce the degradation of p53 at the nonpermissive temperature. Thus, our results identify a novel role for the Cullin-based machinery in regulation of p53.