Pahel G, Aulabaugh A, Short S A, Barnes J A, Painter G R, Ray P, Phelps W C
Wellcome Research Laboratories, Burroughs Wellcome Co., Research Triangle Park, North Carolina 27709.
J Biol Chem. 1993 Dec 5;268(34):26018-25.
The E7 gene of the human papillomaviruses (HPV) encodes a 98-amino acid, multifunctional nuclear phosphoprotein with functional and structural similarities to adenovirus E1A and the papovavirus T antigens. E7 is a viral oncoprotein, which will cooperate with an activated ras oncogene to transform primary rodent cells, and can cooperate with the HPV E6 protein for the efficient immortalization of primary human keratinocytes. Due to the compelling epidemiological and experimental association between HPV infection and cervical cancer, we have undertaken a detailed study of the structure of the HPV16 E7 protein. The E7 protein was expressed in Escherichia coli as a native, unfused polypeptide, and soluble protein was purified by conventional chromatographic techniques. The purified protein was assessed for various biochemical and biophysical properties. Purified E7 binds the retinoblastoma protein avidly and specifically, and it can dissociate the E2F transcription factor when assayed in vitro. Circular dichroism spectroscopy indicated that E7 reversibly binds Zn2+ and Cd2+, resulting in a substantial increase in the alpha-helical content of the metal-bound E7 consistent with the stabilization of a hydrophobic core in the COOH terminus of the protein.
人乳头瘤病毒（HPV）的E7基因编码一种含98个氨基酸的多功能核磷蛋白，它在功能和结构上与腺病毒E1A及乳头多瘤空泡病毒T抗原相似。E7是一种病毒癌蛋白，它能与激活的ras癌基因协同作用转化原代啮齿动物细胞，还能与HPV E6蛋白协同作用使原代人角质形成细胞高效永生化。鉴于HPV感染与宫颈癌之间存在令人信服的流行病学及实验关联，我们对HPV16 E7蛋白的结构进行了详细研究。E7蛋白在大肠杆菌中作为天然的未融合多肽表达，可溶性蛋白通过常规色谱技术纯化。对纯化后的蛋白进行了各种生化和生物物理性质的评估。纯化的E7能与视网膜母细胞瘤蛋白紧密且特异性结合，在体外检测时它能使E2F转录因子解离。圆二色光谱表明E7能可逆地结合Zn2+和Cd2+，导致与金属结合的E7的α-螺旋含量大幅增加，这与该蛋白COOH末端疏水核心的稳定相一致。
