PULSE DIPOLAR ESR STUDY ON INTERACTION OF HIV-1 NUCLEOCAPSID PROTEIN NCP7

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 奥尔巴尼大学的查尔斯·P·斯科尔斯教授正在积极研究HIV-1复制的潜在机制。HIV-1复制的关键步骤是通过逆转录酶(RT)将HIV-1基因组RNA反转录成双链DNA。两种病毒蛋白，RT酶和一个小的核衣壳蛋白NCp7，它是众所周知的核酸伴侣指导这一过程。在线性DNA合成开始时，新合成的负链强终止DNA((-)ssDNA)通过反式激活反应元件(TAR)RNA与ctar DNA序列的杂交反应转移到基因组RNA的3‘端。由于这两个TAR序列都显示出稳定的发夹结构，NCp7需要破坏TAR结构的稳定性才能伴随它们的杂交。NCp7的特征是两个锌指，在HIV-1的生命周期中发挥关键作用，为抗病毒治疗提供了一个有希望的靶点。已有研究表明，NCp7通过促进互补的反式激活反应元件(TAR)RNA和ctar DNA茎环序列的退火来陪伴第一链转移。这严重依赖于NCp7瞬间融化其末端碱基对的能力。NCp7的失稳活性是由折叠的锌指表面的疏水平台介导的，这限制了寡核苷酸的灵活性。TAR和CTAR序列的不稳定可以由单个手指基序介导，而退火活性需要两个手指。NCp7导致第二链转移所涉及的引物结合位点(PBS)茎环的有限失稳。然而，NCp7可以通过稳定其部分自互补环的退火来伴随它们的同源二聚化。NCp7倾向于促进部分互补序列的二聚化，这可能有利于病毒序列之间的二次接触，从而促进重组和病毒多样性。此外，NCp7通过陪伴亲吻环中间产物，通过延伸环和削弱茎的上碱基对来促进第二链转移。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Prof. Charles P. Scholes from Albany University is actively studying the mechanisms underlying HIV-1 replication. A critical step in HIV-1 replication is reverse transcription of HIV-1 genomic RNA to double-stranded DNA by reverse transcriptase (RT). Two viral proteins, the RT enzyme and a small nucleocapsid protein NCp7, which is well-known nucleic acid chaperone direct this process. At the beginning of the linear DNA synthesis, the newly made minus-strand strong-stop DNA ((-)ssDNA) is transferred to the 3'end of the genomic RNA by means of an hybridization reaction between transactivation response element (TAR) RNA and cTAR DNA sequences. Since both TAR sequences exhibit stable hairpin structures, NCp7 needs to destabilize the TAR structures in order to chaperone their hybridization. NCp7 is characterized by two zinc fingers that plays a key role in HIV-1 life cycle and presents a promising target for an antiviral therapy. It has been shown that NCp7 chaperones the first strand transfer by promoting the annealing of the complementary transactivation response element (TAR) RNA and cTAR DNA stem-loop sequences. This critically relies on NCp7 ability to transiently melt their terminal base pairs. The destabilization activity of NCp7 is mediated by a hydrophobic plateau at the surface of the folded zinc fingers, which restricted the oligonucleotide flexibility. The destabilizing of the TAR and cTAR sequences can be mediated by a single finger motif, while the annealing activity requires the two fingers. NCp7 induces a limited destabilization of the primer binding site (PBS) stem-loops involved in the second strand transfer. However, NCp7 can chaperone their homodimerization, by stabilizing the annealing of their partly self-complementary loops. The propensity of NCp7 to promote the dimerization of partly complementary sequences may favor secondary contacts between viral sequences and thus, recombination and viral diversity. Moreover, NCp7 promotes the second strand transfer, by chaperoning a kissing-loop intermediate, through an extension of the loops and a weakening of the upper base pair of the stem.