Strand Displacement Synthesis in the Central Polypurine Tract Region of HIV-1 Promotes DNA to DNA Strand Transfer Recombination*
Strand Displacement Synthesis in the Central Polypurine Tract Region of HIV-1 Promotes DNA to DNA Strand Transfer Recombination*
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HIV-1 中央多嘌呤束区域的链置换合成促进 DNA 到 DNA 链转移重组*
DOI：
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发表时间：
1996
影响因子：
4.8
通讯作者：
R. Bambara
中科院分区：
文献类型：
--
作者：
G. M. Fuentes;C. Palaniappan;P. Fay;R. Bambara
在人类免疫缺陷病毒(HIV)中发现了两个不同的正链起始点，即中央多尿路(CPPT)和位于U3区上游的多尿路(U3-PPT)。当从U3-PPT合成的产物达到cPPT时，拉长的引物导致从cPPT产生的产物有限的链位移。我们检测了逆转录酶(RT)催化的链转移重组是否被这一过程所促进。使用具有移位区病毒序列的底物，我们测量了从供体DNA到受体DNA的延伸DNA引物的转移。链转移合成只有在RT进行链置换合成时才有效。转移效率与受体浓度直接相关，与反应时间无关。可以转移到含有与模板DNA同源的80、40或20个核苷酸的受体。使用不同的受体，我们发现DNA到DNA的转移发生在整个供体模板的位置，除了5‘端附近。这表明cPPT区域下游的一些序列可以促进转移，但一旦合成进行到下游片段完全移位的点，就不允许转移。当使用包含非病毒序列的模板进行DNA到DNA转移反应时，转移效率显著下降。这表明转移效率由所使用的模板的顺序决定。HIV-RT RNaseH依赖于RNA模板之间的链转移是有很好的文献记载的。我们提出了一种完全不同的DNA到DNA转移的机制，这与RNaseH减去RT执行这一反应的能力一致。如果这些DNA到DNA的转移事件在体内发生，它们将导致正链重组。
Two distinct plus strand initiation sites have been identified in human immunodeficiency virus (HIV), the central polypurine tract (cPPT) and the polypurine tract located just upstream of the U3 region (U3-PPT). When synthesis from the U3-PPT reaches the cPPT, the elongating primer causes limited strand displacement of the product created from the cPPT. We examined whether reverse transcriptase (RT) catalyzed strand transfer recombination is promoted by this process. Using a substrate having the viral sequence of the displaced region, we measured transfer of an elongating DNA primer from a donor DNA to an acceptor DNA. Strand transfer synthesis was only efficient when RT was performing strand displacement synthesis. Transfer efficiency was directly related to acceptor concentration but independent of the reaction time. Transfer could occur to acceptors containing 80, 40, or 20 nucleotides of homology with the template DNA. Using different acceptors, we found that DNA to DNA transfer occurred at positions throughout the donor template, except near the 5′ end. This shows that a number of the sequences downstream of the cPPT region can promote transfer, but once synthesis has progressed to the point where the downstream segment is completely displaced transfer is not allowed. When the DNA to DNA transfer reactions were performed using a template containing nonviral sequences, the transfer efficiency dropped significantly. This indicates that transfer efficiency is determined by the sequences of the templates used. HIV-RT RNase H-dependent strand transfer between RNA templates is well documented. We propose a quite different mechanism for DNA to DNA transfer, consistent with the ability of RNase H minus RT to perform this reaction. If these DNA to DNA transfer events occur in vivo, they will result in plus strand recombination.
DOI：
10.1073/pnas.87.4.1556
发表时间：
1990-02-01
影响因子：
11.1
作者：
HU, WS;TEMIN, HM
通讯作者：
TEMIN, HM
影响因子：
56.9
作者：
HU, WS;TEMIN, HM
通讯作者：
TEMIN, HM