Khorasanizadeh S, Campos-Olivas R, Summers M F
Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD, 21250, USA.
J Mol Biol. 1999 Aug 13;291(2):491-505. doi: 10.1006/jmbi.1999.2986.
The solution structure of the capsid protein (CA) from the human T-cell leukemia virus type one (HTLV-I), a retrovirus that causes T-cell leukemia and HTLV-I-associated myelopathy in humans, has been determined by NMR methods. The protein consists of independent N and C-terminal domains connected by a flexible linker. The domains are structurally similar to the N-terminal "core" and C-terminal "dimerization" domains, respectively, of the human immunodeficiency virus type one (HIV-1) and equine infectious anemia virus (EIAV) capsid proteins, although several important differences exist. In particular, hydrophobic residues near the major homology region are partially buried in HTLV-I CA, which is monomeric in solution, whereas analogous residues in HIV-1 and EIAV CA project from the C-terminal domain and promote dimerization. These differences in the structure and oligomerization state of the proteins appear to be related to, and possibly controlled by, the oxidation state of conserved cysteine residues, which are reduced in HTLV-I CA but form a disulfide bond in the HIV-1 and EIAV CA crystal structures. The results are consistent with an oxidative capsid assembly mechanism, in which CA oligomerization or maturation is triggered by disulfide bo nd formation as the budding virus enters the oxidizing environment of the bloodstream.
人类嗜T淋巴细胞病毒1型（HTLV-I）是一种可导致人类T细胞白血病和HTLV-I相关脊髓病的逆转录病毒，其衣壳蛋白（CA）的溶液结构已通过核磁共振方法确定。该蛋白由通过柔性接头连接的独立N端和C端结构域组成。这些结构域在结构上分别与人免疫缺陷病毒1型（HIV-1）和马传染性贫血病毒（EIAV）衣壳蛋白的N端“核心”和C端“二聚化”结构域相似，尽管存在一些重要差异。特别是，主要同源区域附近的疏水残基在HTLV-I CA中部分埋藏，HTLV-I CA在溶液中为单体，而HIV-1和EIAV CA中的类似残基从C端结构域突出并促进二聚化。蛋白质结构和寡聚化状态的这些差异似乎与保守半胱氨酸残基的氧化状态有关，并且可能受其控制，这些残基在HTLV-I CA中被还原，但在HIV-1和EIAV CA晶体结构中形成二硫键。结果与氧化衣壳组装机制一致，即当出芽病毒进入血液的氧化环境时，二硫键的形成触发CA寡聚化或成熟。
