Guilley H, Richards K E, Jonard G
Laboratoire de Virologie, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France.
EMBO J. 1983;2(2):277-82. doi: 10.1002/j.1460-2075.1983.tb01417.x.
The double-stranded circular DNA encapsidated within cauliflower mosaic virus (CaMV) particles contains three single-stranded discontinuities, two in one strand and one in the other, so that, upon denaturation, three linear single-stranded DNAs are produced. Here we show that a fourth much smaller single-stranded DNA, termed alpha1, is also present in denatured CaMV DNA preparations. The 5' extremity of alpha1 is identical to that of the alpha-strand, the strand of DNA possessing only one interruption, while its 3' extremity lies just two nucleotides downstream from a major transcription initiation site. We also show that the interrupted strand at each discontinuity sometimes has a single ribonucleotide in place of a deoxyribonucleotide at its 5' extremity. Oligoribonucleotide chains of eight and 10 residues in length have also been detected at the 5' end of one of the discontinuities. These structures are thought to be the vestiges of primers which have not been completely excised prior to encapsidation of the DNA. The possibility that synthesis of the alpha-strand occurs by reverse transcription of viral RNA using initiator tRNA(met) as primer is discussed.
包裹在花椰菜花叶病毒（CaMV）颗粒中的双链环状DNA含有三个单链间断，一条链上有两个，另一条链上有一个，因此在变性时会产生三条线性单链DNA。我们在此表明，在变性的CaMV DNA制剂中还存在第四条小得多的单链DNA，称为α1。α1的5'末端与α链的5'末端相同，α链是仅具有一个间断的DNA链，而其3'末端位于一个主要转录起始位点下游仅两个核苷酸处。我们还表明，每个间断处的间断链在其5'末端有时会有一个单核糖核苷酸代替脱氧核糖核苷酸。在其中一个间断的5'末端还检测到了长度为8和10个残基的寡核糖核苷酸链。这些结构被认为是在DNA包装之前尚未完全切除的引物的残余物。本文讨论了使用起始tRNA(met)作为引物通过病毒RNA的逆转录合成α链的可能性。
