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首页> 外文期刊>Journal of Molecular Biology >Destabilization of the HIV-1 Complementary Sequence of TAR by the Nucleocapsid Protein Through Activation of Conformational Fluctuations.
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Destabilization of the HIV-1 Complementary Sequence of TAR by the Nucleocapsid Protein Through Activation of Conformational Fluctuations.

机译：核衣壳蛋白通过构象波动的激活使TAR的HIV-1互补序列不稳定。

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The nucleocapsid protein NCp7 of HIV-1 possesses nucleic acid chaperone properties that are critical for the two obligatory strand transfer reactions required for the synthesis of a complete proviral DNA by reverse transcriptase. The first DNA strand transfer relies on the destabilization by NCp7 of double-stranded segments of the transactivation response region (TAR) sequence at the 3' end of the genomic RNA and the complementary sequence cTAR at the 3' terminus of minus strong-stop DNA, the early product of reverse transcription. In order to determine the dynamics of NCp7-mediated nucleic acid destabilization, we investigated by time-resolved fluorescence spectroscopy and two photon fluorescence correlation spectroscopy, the interaction of a doubly labeled cTAR sequence with NC(12-55) containing NCp7 CCHC zinc fingers and flanking basic amino acid residues. From the chemical rates and the activation energy associated with the conformational fluctuations observed in the absence of NC, it is concluded that such fluctuations are associated with the opening and closing of the double-stranded terminal segments of cTAR. The destabilizing activity of NC(12-55) occurs mainly through a major increase of the opening rate constant of cTAR. Moreover, NC appears to augment the number of pathways between the open and closed states of cTAR, suggesting that it initiates melting of base-pairs at different locations within the terminal segments of cTAR. This activity of NC on the dynamics of cTAR secondary structure is thought to be critical for the formation of the cTAR-TAR complex, which is essential for the specificity and extent of proviral DNA synthesis by reverse transcriptase.
机译：HIV-1的核衣壳蛋白NCp7具有核酸伴侣特性，这对于通过逆转录酶合成完整的原病毒DNA所需的两个强制性链转移反应至关重要。第一次DNA链转移依赖于基因组RNA 3'末端的反转录激活区（TAR）序列的双链区段和负强终止DNA的3'末端的互补序列cTAR的NCp7失稳。 ，逆转录的早期产物。为了确定NCp7介导的核酸去稳定的动力学，我们通过时间分辨荧光光谱法和两个光子荧光相关光谱法研究了双标记cTAR序列与包含NCp7 CCHC锌指的NC（12-55）的相互作用。侧翼碱性氨基酸残基。根据在不存在NC的情况下观察到的化学速率和与构象波动相关的活化能，可以得出结论，这种波动与cTAR双链末端片段的打开和闭合有关。 NC（12-55）的去稳定化活性主要是通过大大提高cTAR的打开速率常数来实现的。此外，NC似乎增加了cTAR打开和关闭状态之间的途径数量，这表明它在cTAR末端片段内不同位置启动了碱基对的解链。 NC对cTAR二级结构动力学的这种活性被认为对cTAR-TAR复合物的形成至关重要，这对于通过逆转录酶合成前病毒DNA的特异性和程度至关重要。

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