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

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 教授来自奥尔巴尼大学的查尔斯·P·斯科尔斯正在积极研究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逆转录为双链DNA。两种病毒蛋白，RT酶和小的核衣壳蛋白NCp 7，这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，通过反式激活反应元件（TAR）RNA和cTAR DNA序列之间的杂交反应，将新制备的负链强终止DNA（（-）ssDNA）转移到基因组RNA的3 '末端。由于两个TAR序列都表现出稳定的发夹结构，因此NCp 7需要使TAR结构不稳定，以便陪伴它们的杂交。 NCp 7的特征在于两个锌指，其在HIV-1生命周期中起关键作用，并为抗病毒治疗提供了有希望的靶点。 已经表明，NCp 7通过促进互补反式激活反应元件（TAR）RNA和cTAR DNA茎环序列的退火来陪伴第一链转移。这主要依赖于NCp 7瞬时熔化其末端碱基对的能力。NCp 7的去稳定活性是由折叠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序列的去稳定化可以由单个指基序介导，而退火活性需要两个指。NCp 7诱导参与第二链转移的引物结合位点（PBS）茎-环的有限去稳定化。然而，NCp 7可以通过稳定它们的部分自互补环的退火来陪伴它们的同源二聚化。NCp 7促进部分互补序列二聚化的倾向可能有利于病毒序列之间的二次接触，从而有利于重组和病毒多样性。此外，NCp 7促进第二链转移，通过陪伴吻环中间体，通过延长环和削弱茎的上部碱基对。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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.