Division of Virology, MRC National Institute for Medical Research, London, United Kingdom.
PLoS Pathog. 2011 Mar;7(3):e1002011. doi: 10.1371/journal.ppat.1002011. Epub 2011 Mar 31.
After entry into target cells, retroviruses encounter the host restriction factors such as Fv1 and TRIM5α. While it is clear that these factors target retrovirus capsid proteins (CA), recognition remains poorly defined in the absence of structural information. To better understand the binding interaction between TRIM5α and CA, we selected a panel of novel N-tropic murine leukaemia virus (N-MLV) escape mutants by a serial passage of replication competent N-MLV in rhesus macaque TRIM5α (rhTRIM5α)-positive cells using a small percentage of unrestricted cells to allow multiple rounds of virus replication. The newly identified mutations, many of which involve changes in charge, are distributed over the outer 'top' surface of N-MLV CA, including the N-terminal β-hairpin, and map up to 29 A(o) apart. Biological characterisation with a number of restriction factors revealed that only one of the new mutations affects restriction by human TRIM5α, indicating significant differences in the binding interaction between N-MLV and the two TRIM5αs, whereas three of the mutations result in dual sensitivity to Fv1(n) and Fv1(b). Structural studies of two mutants show that no major changes in the overall CA conformation are associated with escape from restriction. We conclude that interactions involving much, if not all, of the surface of CA are vital for TRIM5α binding.
逆转录病毒进入靶细胞后，会遇到 Fv1 和 TRIM5α 等宿主限制因子。虽然很明显这些因子针对的是逆转录病毒衣壳蛋白（CA），但在缺乏结构信息的情况下，其识别仍未得到明确界定。为了更好地理解 TRIM5α 和 CA 之间的结合相互作用，我们通过在恒河猴 TRIM5α（rhTRIM5α）阳性细胞中用小比例未受限制的细胞进行复制有效的 N-MLV 的连续传代，选择了一组新型 N 嗜性鼠白血病病毒（N-MLV）逃逸突变体。允许多轮病毒复制。新鉴定的突变，其中许多涉及电荷变化，分布在 N-MLV CA 的外“顶”表面上，包括 N 端 β-发夹，并映射高达 29Å 。用多种限制因子进行的生物学特征分析表明，只有一个新突变会影响人 TRIM5α 的限制，表明 N-MLV 和两种 TRIM5α 之间的结合相互作用存在显著差异，而三个突变导致对 Fv1(n) 和 Fv1(b) 的双重敏感性。对两个突变体的结构研究表明，从限制中逃逸出来与 CA 整体构象没有重大变化有关。我们得出的结论是，涉及 CA 表面的大部分（如果不是全部）的相互作用对于 TRIM5α 结合至关重要。
