Department of Biology, Indiana University, Bloomington, IN 47405, United States.
Department of Biology, Indiana University, Bloomington, IN 47405, United States.
Virology. 2019 May;531:31-39. doi: 10.1016/j.virol.2019.02.016. Epub 2019 Feb 23.
Sindbis virus particles contain the viral proteins capsid, E1 and E2, and low levels of a small membrane protein called TF. TF is produced during a (-1) programmed ribosomal frameshifting event during the translation of the structural polyprotein. TF from Sindbis virus-infected cells is present in two palmitoylated states, basal and maximal; unpalmitoylated TF is not detectable. Mutagenesis studies demonstrated that without palmitoylation, TF is not incorporated into released virions, suggesting palmitoylation of TF is a regulated step in virus assembly. In this work, we identified Domains within the TF protein that regulate its palmitoylation state. Mutations and insertions in Domain III, a region proposed to be in the cytoplasmic loop of TF, increase levels of unpalmitoylated TF found during an infection but still unpalmitoylated TF was not incorporated into virions. Mutations in Domain IV, the TF unique region, are likely to impact the balance between basal and maximal palmitoylation.
辛德毕斯病毒颗粒包含病毒蛋白衣壳、E1 和 E2，以及少量称为 TF 的小膜蛋白。TF 是在结构多蛋白翻译过程中的（-1）程序性核糖体移码事件中产生的。来自辛德毕斯病毒感染细胞的 TF 存在两种棕榈酰化状态，基础状态和最大状态；不可检测到未棕榈酰化的 TF。诱变研究表明，没有棕榈酰化，TF 就不会被掺入释放的病毒粒子中，这表明 TF 的棕榈酰化是病毒组装的一个受调控的步骤。在这项工作中，我们确定了 TF 蛋白中调节其棕榈酰化状态的结构域。在 III 结构域中进行突变和插入，该区域被提议位于 TF 的细胞质环中，增加了感染过程中发现的未棕榈酰化 TF 的水平，但仍未棕榈酰化的 TF 未被掺入病毒粒子中。IV 结构域中的突变，TF 的独特区域，可能会影响基础和最大棕榈酰化之间的平衡。
