Jacobsen K, Laursen N B, Jensen E O, Marcker A, Poulsen C, Marcker K A
Department of Molecular Biology and Plant Physiology, University of Aarhus, Denmark.
Plant Cell. 1990 Jan;2(1):85-94. doi: 10.1105/tpc.2.1.85.
Three different nuclear factors recognizing short AT-rich DNA sequences were identified in different organs of soybean. One factor (NAT2) was found to be present in mature nodules, another factor (NAT1) was detected in roots and nodules, and a third one (LAT1) was only observed in leaves. All three factors recognized several DNA sequences in the promoter region of the soybean nodulin N23 gene. Footprinting, deletion, and point mutation analyses revealed different binding properties for all three factors and further showed that even single base pair substitutions had a dramatic effect on binding affinity. The LAT1 and NAT1 factors were released from chromatin by extraction with a low-salt buffer and were soluble in 2% trichloroacetic acid, implying a relationship to high-mobility group (HMG) proteins. DNA binding studies further indicated a functional relationship of these factors to the human HMG I protein. Purification of the LAT1 factor from leaf nuclei revealed the presence of two polypeptides with molecular masses of 21 kilodaltons and 23 kilodaltons, respectively, binding the same DNA sequence with equal affinity.
在大豆的不同器官中鉴定出了三种识别富含AT短DNA序列的核因子。一种因子（NAT2）存在于成熟根瘤中，另一种因子（NAT1）在根和根瘤中检测到，第三种因子（LAT1）仅在叶片中观察到。所有这三种因子都识别大豆根瘤菌素N23基因启动子区域中的几个DNA序列。足迹、缺失和点突变分析揭示了所有这三种因子不同的结合特性，并进一步表明即使是单个碱基对的替换也会对结合亲和力产生显著影响。LAT1和NAT1因子通过用低盐缓冲液提取而从染色质中释放出来，并且可溶于2%的三氯乙酸，这意味着它们与高迁移率族（HMG）蛋白有关。DNA结合研究进一步表明这些因子与人类HMG I蛋白存在功能关系。从叶核中纯化LAT1因子显示存在两种分别具有21千道尔顿和23千道尔顿分子量的多肽，它们以相同的亲和力结合相同的DNA序列。
