Potter H, Dressler D
Proc Natl Acad Sci U S A. 1976 Sep;73(9):3000-4. doi: 10.1073/pnas.73.9.3000.
This paper deals with the nature of recombination intermediates. Using the electron microscope to study the DNA of the plasmid colicin E1, we have observed more than 800 molecules that appear to represent intermediates in the process of recombination. Specifically, after isolating colicin DNA and linearizing it with the restriction enzyme EcoRI, we find crossed molecules with twice the normal colicin DNA content. These forms consist of two genome-length elements held together at a region of DNA homology. The molecules can be recovered from wild type and Rec B-C host cells but are not present among the colicin DNA forms isolated from recombination-deficient Rec A cells. We have termed the experimentally observed molecules "chi forms" and believe that they represent the recombination intermediate of the Holliday model.
本文探讨了重组中间体的性质。利用电子显微镜研究质粒大肠杆菌素E1的DNA，我们观察到800多个分子，它们似乎代表了重组过程中的中间体。具体而言，在分离大肠杆菌素DNA并用限制性内切酶EcoRI将其线性化后，我们发现了DNA含量为正常大肠杆菌素DNA两倍的交叉分子。这些形式由两个基因组长度的元件在DNA同源区域结合在一起组成。这些分子可以从野生型和Rec B-C宿主细胞中回收，但在从重组缺陷型Rec A细胞中分离的大肠杆菌素DNA形式中不存在。我们将实验观察到的分子称为“χ形式”，并认为它们代表了霍利迪模型的重组中间体。
