Cowie A, Kamen R
J Virol. 1986 Feb;57(2):505-14. doi: 10.1128/JVI.57.2.505-514.1986.
Essential nucleotide contacts between the polyomavirus large T antigen and its multiple specific binding regions within the regulatory sequences of the polyomavirus genome were determined in vitro by methylation interference. Methylation of any of the guanine residues of the 5'-G(A/G)GGC-3' pentanucleotide repeats in large-T-antigen-binding regions A, B, C, and 3 (A. Cowie and R. Kamen, J. Virol. 52:750-760, 1984) interfered with T antigen binding. Within regions A, B, and C these pentanucleotides are spaced 5 or 6 base pairs apart. Therefore, the clusters of contacted nucleotides within each of these binding regions are localized along one face of the DNA helix. Methylation of guanines within the sequences between the pentanucleotide repeats did not interfere with binding. The ORI binding region contains four additional pentanucleotide sequences within a region of dyad symmetry. Methylation of only particular guanines of these pentanucleotides interfered with T antigen binding. The spatial arrangement of the pentanucleotides in the ORI is such that the clusters of contacted guanines are situated around the DNA helix, thereby forming a very different arrangement from that found in the other binding regions. A model is discussed in which cooperative interactions between T antigen protomers, recognizing individual pentanucleotides, determines the strength and the function of different T antigen-DNA interactions.
通过甲基化干扰体外确定了多瘤病毒大T抗原与其在多瘤病毒基因组调控序列内的多个特异性结合区域之间的必需核苷酸接触。大T抗原结合区域A、B、C和3（A. Cowie和R. Kamen，《病毒学杂志》52:750 - 760，1984）中5'-G(A/G)GGC-3'五核苷酸重复序列的任何鸟嘌呤残基甲基化都会干扰T抗原结合。在区域A、B和C内，这些五核苷酸相隔5或6个碱基对。因此，这些结合区域中每个区域内的接触核苷酸簇沿着DNA螺旋的一个面定位。五核苷酸重复序列之间的序列内鸟嘌呤甲基化不干扰结合。ORI结合区域在二元对称区域内包含另外四个五核苷酸序列。只有这些五核苷酸的特定鸟嘌呤甲基化会干扰T抗原结合。ORI中五核苷酸的空间排列使得接触鸟嘌呤的簇位于DNA螺旋周围，从而形成与其他结合区域中发现的排列非常不同的排列。讨论了一个模型，其中识别单个五核苷酸的T抗原原体之间的协同相互作用决定了不同T抗原 - DNA相互作用的强度和功能。
