PROTEIN DOMAINS GOVERNING INTERACTIONS BETWEEN E2F, THE RETINOBLASTOMA GENE-PRODUCT, AND HUMAN PAPILLOMAVIRUS TYPE-16 E7 PROTEIN
PROTEIN DOMAINS GOVERNING INTERACTIONS BETWEEN E2F, THE RETINOBLASTOMA GENE-PRODUCT, AND HUMAN PAPILLOMAVIRUS TYPE-16 E7 PROTEIN
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DOI：
10.1128/mcb.13.2.953
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发表时间：
1993-02-01
影响因子：
5.3
通讯作者：
HEIMBROOK, DC
中科院分区：
文献类型：
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作者：
HUANG, PS;PATRICK, DR;HEIMBROOK, DC
人乳头瘤病毒（hpv）是生殖器疣的病因，并有助于人类宫颈癌的发展。HPV E7基因产物在这些疾病中表达，来自HPV 16型和18型的E7基因有助于哺乳动物细胞的转化。该基因的突变和缺失分析表明，该蛋白产物的转化活性与视网膜母细胞瘤基因产物（pRB）直接参与复合物形成的结构域相同。该结构域是E7和其他结合pRB的病毒癌蛋白（包括腺病毒E1A蛋白）共享的两个保守区域（指定为CRI和CRII）之一。HPV 16型E7蛋白与pRB的结合先前已被证明会影响pRB结合DNA和与其他细胞蛋白形成复合物的能力。在目前的研究中，我们通过监测60 kda版本的pRB、pRB60和细胞转录因子E2F之间的关联，绘制了E7蛋白与pRB之间的功能相互作用图谱。我们观察到E7（氨基酸20 ~ 29）的CRII完全阻断了E7全长蛋白的结合，是抑制E2F/pRB60复合物形成的必要条件，但并不足以抑制E2F/pRB60复合物的形成。虽然E1A（氨基酸37至55）的CRI似乎足以与E2F竞争与pRB60的结合，但E7的等效区域既不是必要的也不是充分的。只有含有CRII和至少一部分锌结合结构域（氨基酸60 ~ 98）的E7片段抑制了E2F/pRB60复合物的形成。这些结果表明，pRB60通过重叠但不同的结构域与E7和E2F结合。
Human papillomaviruses (HPVs) are the etiological agents for genital warts and contribute to the development of cervical cancer in humans. The HPV E7 gene product is expressed in these diseases, and the E7 genes from HPV types 16 and 18 contribute to transformation in mammalian cells. Mutation and deletion analysis of this gene suggests that the transforming activity of the protein product resides in the same domain as that which is directly involved in complex formation with the retinoblastoma gene product (pRB). This domain is one of two conserved regions (designated CRI and CRII) shared by E7 and other viral oncoproteins which bind pRB, including adenovirus E1A protein. Binding of HPV type 16 E7 protein to pRB has previously been shown to affect pRB's ability to bind DNA and to form complexes with other cellular proteins. In the current study, we map the functional interaction between E7 protein and pRB by monitoring the association between a 60-kDa version of the pRB, pRB60, and the cellular transcription factor E2F. We observe that CRII of E7 (amino acids 20 to 29), which completely blocks binding of full-length E7 protein, is necessary but not sufficient to inhibit E2F/pRB60 complex formation. While CRI of E1A (amino acids 37 to 55) appears to be sufficient to compete with E2F for binding to pRB60, the equivalent region of E7 is neither necessary nor sufficient. Only E7 fragments that contained both CRII and at least a portion of the zinc-binding domain (amino acids 60 to 98) inhibited E2F/pRB60 complex formation. These results suggest that pRB60 associates with E7 and E2F through overlapping but distinct domains.