Department of Plant Pathology, University of Illinois, Urbana, Illinois 61801.
Proc Natl Acad Sci U S A. 1981 Jul;78(7):4102-6. doi: 10.1073/pnas.78.7.4102.
A double-stranded (ds) DNA which may be a replication intermediate was isolated from bean (Phaseolus vulgaris L. "Top Crop") leaves systemically infected with bean golden mosaic virus, a whitefly-transmitted plant virus with a genome of circular single-stranded (ss) DNA. The isolation method used phenol/chloroform extraction, hydroxyapatite column chromatography, and rate-zonal centrifugation. The dsDNA had sequences complementary to those of viral DNA. The guanine-plus-cytosine content was 35%, and the sedimentation coefficient in alkaline sucrose density gradients was similar to that of viral ssDNA. Digestion of the dsDNA by Hha I endonuclease produced fragments that corresponded exactly in number and size with those produced by complete digestion of circular viral ssDNA by Hha I, when the fragments were denatured and analyzed on polyacrylamide gels. The dsDNA molecule was a circular structure with one discontinuity in one strand; hybridization results suggest that some of a the dsDNA has a discontinuity in the viral strand and some has a discontinuity in the nonviral strand. On the basis of these structures for the dsDNA, a preliminary model for replication of viral DNA is discussed.
从系统感染了豆科黄花叶病毒（一种由粉虱传播的具有圆形单链 DNA 基因组的植物病毒）的菜豆（Phaseolus vulgaris L. "Top Crop"）叶片中分离出一种双链 DNA（dsDNA），可能是一种复制中间体。该分离方法使用了酚/氯仿提取、羟基磷灰石柱层析和速率区带离心。dsDNA 具有与病毒 DNA 互补的序列。鸟嘌呤加胞嘧啶含量为 35%，在碱性蔗糖密度梯度中的沉降系数与病毒 ssDNA 相似。Hha I 内切酶消化 dsDNA 产生的片段数量和大小与 Hha I 完全消化圆形病毒 ssDNA 产生的片段完全一致，当片段变性并在聚丙烯酰胺凝胶上分析时。dsDNA 分子是一种具有单链一处不连续性的环状结构；杂交结果表明，dsDNA 的一些部分在病毒链上有不连续性，而另一些部分在非病毒链上有不连续性。基于这些 dsDNA 的结构，讨论了病毒 DNA 复制的初步模型。
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