Adenovirus E1B 55-Kilodalton Protein Is a p53-SUMO1 E3 Ligase That Represses p53 and Stimulates Its Nuclear Export through Interactions with Promyelocytic Leukemia Nuclear Bodies
Adenovirus E1B 55-Kilodalton Protein Is a p53-SUMO1 E3 Ligase That Represses p53 and Stimulates Its Nuclear Export through Interactions with Promyelocytic Leukemia Nuclear Bodies
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DOI：
10.1128/jvi.01442-10
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发表时间：
2010-09
影响因子：
5.4
通讯作者：
M. Pennella;Yue Liu;J. Woo;Chongwoo A. Kim;A. Berk
中科院分区：
文献类型：
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作者：
M. Pennella;Yue Liu;J. Woo;Chongwoo A. Kim;A. Berk
腺病毒E1 A和E1 B-55 K的致癌转化需要E1 B-55 K抑制p53活性以防止E1 A诱导的细胞凋亡。在病毒感染期间，E1 B-55 K和E4 orf 6取代宿主细胞cullin 5类泛素连接酶的底物结合亚基，导致p53多聚泛素化和蛋白酶体降解。在这里，我们表明E1 B-55 K单独也作为E3 SUMO 1-p53连接酶发挥作用。荧光显微镜研究表明，E1 B-55 K单独，在其他病毒蛋白的情况下，导致p53与E1 B-55 K共定位在早幼粒细胞白血病（PML）核体，核结构域与高浓度的sumoylated蛋白。用活细胞进行的光漂白实验表明，PML核体中p53的E1 B-55 K束缚使p53的体内核迁移率降低近2个数量级。E1 B-55 K诱导的p53类小泛素化有助于对p53功能的最大抑制，因为主要p53类小泛素化位点的突变降低了E1 B-55 K诱导的p53类小泛素化、PML核体中的束缚和E1 B-55 K对p53活性的抑制。E1 B-55 K类小泛素化位点的突变极大地抑制了E1 B-55 K与PML核体的结合，以及在E1 A-E1 B转化细胞中观察到的p53核输出到胞质侵袭体。纯化的E1 B-55 K和p53可能通过形成与p53四聚体的N末端结合的E1 B-55 K二聚体的网络形成高分子量复合物。为了支持这一模型，阻止四聚体形成的p53突变大大减少了E1 B-55 K诱导的PML核小体束缚和p53核输出。这些数据表明，E1 B-55 K与PML核小体的结合通过首先将p53隔离在PML核小体中然后极大地促进其核输出而使p53失活。
ABSTRACT Oncogenic transformation by adenovirus E1A and E1B-55K requires E1B-55K inhibition of p53 activity to prevent E1A-induced apoptosis. During viral infection, E1B-55K and E4orf6 substitute for the substrate-binding subunits of the host cell cullin 5 class of ubiquitin ligases, resulting in p53 polyubiquitinylation and proteasomal degradation. Here we show that E1B-55K alone also functions as an E3 SUMO1-p53 ligase. Fluorescence microscopy studies showed that E1B-55K alone, in the absence of other viral proteins, causes p53 to colocalize with E1B-55K in promyelocytic leukemia (PML) nuclear bodies, nuclear domains with a high concentration of sumoylated proteins. Photobleaching experiments with live cells revealed that E1B-55K tethering of p53 in PML nuclear bodies decreases the in vivo nuclear mobility of p53 nearly 2 orders of magnitude. E1B-55K-induced p53 sumoylation contributes to maximal inhibition of p53 function since mutation of the major p53 sumoylation site decreases E1B-55K-induced p53 sumoylation, tethering in PML nuclear bodies, and E1B-55K inhibition of p53 activity. Mutation of the E1B-55K sumoylation site greatly inhibits E1B-55K association with PML nuclear bodies and the p53 nuclear export to cytoplasmic aggresomes observed in E1A-E1B-transformed cells. Purified E1B-55K and p53 form high-molecular-weight complexes potentially through the formation of a network of E1B-55K dimers bound to the N termini of p53 tetramers. In support of this model, a p53 mutation that prevents tetramer formation greatly reduces E1B-55K-induced tethering in PML nuclear bodies and p53 nuclear export. These data indicate that E1B-55K's association with PML nuclear bodies inactivates p53 by first sequestering it in PML nuclear bodies and then greatly facilitating its nuclear export.