Challberg M D, Ostrove J M, Kelly T J
J Virol. 1982 Jan;41(1):265-70. doi: 10.1128/JVI.41.1.265-270.1982.
We have previously shown that the 5'-terminal deoxycytidine residue of each nascent adenovirus 5 DNA strand synthesized in vitro is covalently linked to the 80-kilodalton (kd) terminal protein precursor via a phosphodiester bond to a serine residue in the protein. When extracts prepared from adenovirus 5-infected cells are incubated with [alpha-33P]dCTP as the only added deoxynucleoside triphosphate, complexes consisting of nucleotide covalently linked to the 80-kd protein can be detected. The nucleotide moieties present in such complexes include d(pC) and d(pCpA), the 5'-terminal nucleotide and dinucleotide of adenovirus 5 DNA, respectively, as well as some longer oligonucleotides. The formation of these complexes requires the presence of adenovirus DNA containing the attached 55-kd terminal protein and ATP. Extracts from H5ts125-infected cells which are defective in DNA replication catalyze complex formation to the same extent as extracts prepared from wild-type infected cells; thus, the presence of the adenovirus-coded 72-kd DNA-binding protein is apparently not required. Most, if not all, of the 80-kd protein-nucleotide complexes that are formed are noncovalently bound to the input viral DNA. These observations are consistent with the protein-priming model for the initiation of adenovirus DNA replication.
我们先前已表明，体外合成的每条新生腺病毒5型DNA链的5'-末端脱氧胞苷残基通过磷酸二酯键与80千道尔顿（kd）末端蛋白前体的丝氨酸残基共价连接。当用[α-33P]dCTP作为唯一添加的脱氧核苷三磷酸孵育从腺病毒5感染细胞制备的提取物时，可以检测到由与80-kd蛋白共价连接的核苷酸组成的复合物。此类复合物中存在的核苷酸部分分别包括腺病毒5型DNA的5'-末端核苷酸d（pC）和二核苷酸d（pCpA），以及一些更长的寡核苷酸。这些复合物的形成需要存在含有附着的55-kd末端蛋白的腺病毒DNA和ATP。来自DNA复制有缺陷的H5ts125感染细胞的提取物催化复合物形成的程度与从野生型感染细胞制备的提取物相同；因此，显然不需要腺病毒编码的72-kd DNA结合蛋白的存在。形成的大多数（如果不是全部）80-kd蛋白 - 核苷酸复合物与输入的病毒DNA非共价结合。这些观察结果与腺病毒DNA复制起始的蛋白质引发模型一致。
