Sugar conformations at hybrid duplex junctions in HIV-1 and Okazaki fragments.
Sugar conformations at hybrid duplex junctions in HIV-1 and Okazaki fragments.
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DOI：
10.1021/bi00054a002
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发表时间：
1993-01
期刊：
影响因子：
2.9
通讯作者：
Miguel Salazar;J. Champoux;Brian R. Reid
中科院分区：
文献类型：
--
作者：
Miguel Salazar;J. Champoux;Brian R. Reid
我们对[序列：见正文]型（其中r和D代表RNA和DNA）的杂交-嵌合双链体的局部构象进行了溶液研究。本研究的目的是研究在杂交DNA八聚体双链体（gccaCTGC）的内部连接的糖构象。（GCAGTGGC）-其中小写字母代表RNA残基。这种双链体代表了冈崎片段的良好模型，其中RNA引物在滞后链的DNA复制期间共价延伸到DNA链中。此外，这种特殊的序列发生在HIV-1逆转录病毒逆转录过程中。本研究选择的嵌合RNA-DNA链和互补的纯DNA链是由tRNA（Lys）引发（-）链DNA合成和随后在HIV-1逆转录病毒整合前通过逆转录酶合成（+）链DNA产生的。尽管逆转录酶的RNase H活性具有不寻常的特异性，它切割RNA c-a磷酸二酯而不是连接a-C键，但我们发现RNA c-a磷酸二酯而不是连接a-C键之间没有重大结构差异。我们发现RNA糖构象之间没有重大结构差异--所有RNA糖都以正常的C3 '-内A型构象存在。相反，我们发现嵌合链的第一个DNA残基（5C）呈现C4 '-exo到O 4'-endo范围内的糖构象（P = 54-90度）。此外，该双链体的杂交片段比先前对于[序列：见正文]类型的双链体所假设的更具有异源性。（250字处删节）
We have carried out a solution study of the local conformation in a hybrid-chimeric duplex of the [sequence: see text] type (where r and D represent RNA and DNA). The object of this study was to investigate the sugar conformations at the internal junction in the hybrid-DNA octamer duplex (gccaCTGC). (GCAGTGGC)--where the lower-case letters represent RNA residues. Such duplexes represent good models for Okazaki fragments in which RNA primers are covalently extended into DNA strands during DNA replication of the lagging strand. Furthermore, this particular sequence occurs during HIV-1 retrovirus reverse transcription. The chimeric RNA-DNA strand and the complementary pure DNA strand chosen for this study result from the priming of (-)-strand DNA synthesis by tRNA(Lys) and subsequent (+)-strand DNA synthesis by reverse transcriptase prior to HIV-1 retrovirus integration. Despite the unusual specificity of the RNase H activity of reverse transcriptase, which cleaves the RNA c-a phosphodiester rather than the junction a-C linkage, we found no major structural differences among the RNA c-a phosphodiester rather than the junction a-C linkage, we found no major structural differences among the RNA sugar conformations--all RNA sugars were found in the normal C3'-endo A-form conformation. Instead, we find that the first DNA residue of the chimeric strand (5C) assumes a sugar conformation in the C4'-exo to O4'-endo range (P = 54-90 degrees). Furthermore, the hybrid segment of this duplex is more heteronomous than previously assumed for duplexes of the [sequence: see text] type.(ABSTRACT TRUNCATED AT 250 WORDS)