Characterization of the prototype foamy virus envelope glycoprotein receptor-binding domain
Characterization of the prototype foamy virus envelope glycoprotein receptor-binding domain
复制标题
DOI：
10.1128/jvi.00460-06
复制
发表时间：
2006-08-01
影响因子：
5.4
通讯作者：
Lindemann, Dirk
中科院分区：
文献类型：
--
作者：
Duda, Anja;Lueftenegger, Daniel;Lindemann, Dirk
泡沫病毒（FV）糖蛋白前体gp 130（Env）经历高度不寻常的生物合成，导致产生三个颗粒相关的成熟亚基，前导肽（LP）、表面（SU）和跨膜（TM）。关于FV Env胞外结构域的结构和功能信息很少。在这项研究中，我们的特点是原型FV（PFV）Env受体结合域（RBD）的重组PFV Env免疫粘附素结合靶细胞的流式细胞仪分析。C-末端TM亚基的胞外结构域以及同源LP对分泌途径的重组免疫粘附素的靶向作用均被用于靶细胞结合，表明PFV Env RBD包含在SU亚基内。SU结构域的N-和C-末端缺失分析显示跨越氨基酸（aa）225至555的最小连续RBD;然而，覆盖aa 397至483区域的内部缺失（但不包括aa 262至300或aa 342至396）耐受，对宿主细胞结合无显著影响。对PFV SU中的单个半胱氨酸点突变体的分析表明，只有大多数位于氨基酸397至483的非必需区域的突变体保留了残留的结合活性。有趣的是，对各种N-糖基化位点突变体的分析表明，碳水化合物链与N-391的连接对于与受体的直接相互作用或PFV Env RBD的正确折叠具有重要作用。综上所述，这些结果表明跨越aa 225至396和aa 484至555的二分序列基序对于PFV Env RBD的形成是必需的，其中位置391处的N-糖基化位点对于宿主细胞结合起关键作用。
The foamy virus (FV) glycoprotein precursor gp130(Env), undergoes a highly unusual biosynthesis, resulting in the generation of three particle-associated, mature subunits, leader peptide (LP), surface (SU), and transmembrane (TM). Little structural and functional information on the extracellular domains of FV Env is available. In this study, we characterized the prototype FV (PFV) Env receptor-binding domain (RBD) by flow cytometric analysis of recombinant PFV Env immunoadhesin binding to target cells. The extracellular domains of the C-terminal TM subunit as well as targeting of the recombinant immunoadhesins by the cognate LP to the secretory pathway were dispensable for target cell binding, suggesting that the PFV Env RBD is contained within the SU subunit. N- and C-terminal deletion analysis of the SU domain revealed a minimal continuous RBD spanning amino acids (aa) 225 to 555; however, internal deletions covering the region from aa 397 to 483, but not aa 262 to 300 or aa 342 to 396, were tolerated without significant influence on host cell binding. Analysis of individual cysteine point mutants in PFV SU revealed that only most of those located in the nonessential region from aa 397 to 483 retained residual binding activity. Interestingly, analysis of various N-glycosylation site mutants suggests an important role of carbohydrate chain attachment to N-391, either for direct interaction with the receptor or for correct folding of the PFV Env RBD. Taken together, these results suggest that a bipartite sequence motif spanning aa 225 to 396 and aa 484 to 555 is essential for formation of the PFV Env RBD, with N-glycosylation site at position 391 playing a crucial role for host cell binding.