PDF(Pubmed)
Abstract：
In the fullerene cone HIV-1 capsid, the central channels of the hexameric and pentameric capsomers each contain a ring of arginine (Arg18) residues that perform essential roles in capsid assembly and function. In both the hexamer and pentamer, the Arg18 rings coordinate inositol hexakisphosphate, an assembly and stability factor for the capsid. Previously, it was shown that amino-acid substitutions of Arg18 can promote pentamer incorporation into capsid-like particles (CLPs) that spontaneously assemble in vitro under high-salt conditions. Here, we show that these Arg18 mutant CLPs contain a non-canonical pentamer conformation and distinct lattice characteristics that do not follow the fullerene geometry of retroviral capsids. The Arg18 mutant pentamers resemble the hexamer in intra-oligomeric contacts and form a unique tetramer-of-pentamers that allows for incorporation of an octahedral vertex with a cross-shaped opening in the hexagonal capsid lattice. Our findings highlight an unexpected degree of structural plasticity in HIV-1 capsid assembly.
摘要：
在富勒烯锥HIV-1衣壳中,六聚体和五聚体衣聚体的中心通道各自含有在衣壳组装和功能中发挥重要作用的精氨酸(Arg18)残基环。在六聚体和五聚体中，Arg18环配位肌醇六磷酸，衣壳的组装和稳定性因素。以前,结果表明，Arg18的氨基酸取代可以促进五聚体掺入到衣壳样颗粒（CLP）中，这些颗粒在高盐条件下在体外自发组装。这里,我们表明，这些Arg18突变体CLP包含非规范五聚体构象和独特的晶格特征，不遵循逆转录病毒衣壳的富勒烯几何形状。Arg18突变五聚体类似于寡聚物内部接触中的六聚体，并形成独特的五聚体四聚体，允许在六方衣壳晶格中掺入具有十字形开口的八面体顶点。我们的发现强调了HIV-1衣壳组装中意想不到的结构可塑性。
