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首页> 外文期刊>Biochemistry >Mechanism of Nucleocapsid Protein Catalyzed Structural Isomerization of the Dimerization Initiation Site of HIV-1
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Mechanism of Nucleocapsid Protein Catalyzed Structural Isomerization of the Dimerization Initiation Site of HIV-1

机译：HIV-1二聚化起始位点的核衣壳蛋白催化结构异构的机制

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摘要

Dimerization of two homologous strands of genomic RNA is an essential feature of retroviral replication. In the human immunodeficiency virus type 1 (HIV-1), a conserved stem-loop sequence, the dimerization initiation site (DIS), has been identified as the domain primarily responsible for initiation of this aspect of viral assembly. The DIS loop contains an autocomplementary hexanucleotide seqeence flanked by highly conserved 5' and 3' purines and can form a homodimer through a loop-loop kissing intreaction. In a structural rearrangement activated by the HIV-1 nucleocapsid protein (NCp7) and considered to be associated with viral particle maturation, the DIS dimer isoforms have been unambiguously distinguished, allowing a detailed examination of the kinetics of this RNA structural isomerization and a characterization of the role of NCp7 in the reaction. In the presence of divalent cations, the DIS kissing dimer is found to be kinetically trapped and converts to the extended duplex isoform only upon addition of NCp7. NCp7 is demonstrated to act catalytically in inducing the structural isomerization by accelerating the rate of strand exchange between the two hairpin stem helices, without disruption of the loop-loop helix. Observation of an apparent maximum conversion rate for NCp7-activated DIS isomerization, however, requires protein concentrations in excess of the 2:1 stoichiometry estimated for high-affinity NCp7 binding to the DIS kissing dimer, indicating tht transient interactions with additional NCp7 (s) may be required for catalysis.
机译：两种基因组RNA的二聚化是逆转录病毒复制的必要特征。在人免疫缺陷病毒类型1（HIV-1）中，已经鉴定了保守的茎环序列，二聚化引发位点（DIS）作为主要负责引发病毒组件的这一方面的域。 DIS环含有由高度保守的5'和3'嘌呤侧翼的自占六核苷酸Seqeence，并且可以通过环路环接吻尿液形成同型二聚体。在由HIV-1核衣壳蛋白（NCP7）激活的结构重排中并且被认为与病毒颗粒成熟有关，DIS二聚体同种型已经明确区分，允许详细检查该RNA结构异构化的动力学和表征NCP7在反应中的作用。在二价阳离子的存在下，发现DIS接吻二聚体在加入NCP7时仅被动力学捕获并转换为扩展双工同系。证明NCP7通过加速两个发夹杆螺旋之间的股线交换速率而致催化诱导结构异构化，而不会破坏环路环螺旋。然而，观察NCP7活化DIS异构化的表观最大转化率，需要超过2：1化学计量的蛋白质浓度，估计与DIS接吻二聚体的高亲和力NCP7结合，表明与额外的NCP7的瞬态相互作用可能需要催化。

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  • 来源
    《Biochemistry》 |2002年第50期|共9页
  • 作者

    Manuel J.Rist; John P.Marino;

  • 作者单位

    Center for Advanced Research in Biotechnology of the University of Maryland and the National Institute for Standards and Technology 9600 Gudelsky Drive Rockville Raryland 20850;

    Center for Advanced Research in Biotechnology of the University of Maryland and the National Institute for Standards and Technology 9600 Gudelsky Drive Rockville Raryland 20850;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物化学;
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