MECHANISMS OF VIRAL PATHOGENESIS

小鼠细胞内宿主的高效抗流感病毒活性 MXL蛋白刺激了寻找相关的、潜在的抗病毒药物 其他生物体中的蛋白质。到目前为止，共有12个相关序列 已经被克隆，并分析了一些相应的蛋白质。这个 Mx蛋白家族由看似不同的成员组成， 包括非抗病毒功能。下列子组可以是 独特的：1)干扰素调节的抗病毒蛋白(如小鼠 MXL，人MXA)；2)干扰素调节的无抗病毒蛋白 活性(如大鼠MX3、人MXB)；3)重要的构成蛋白 用于适当的胞吐蛋白运输(例如酵母VPS 1)；4) 在内吞作用中很重要的构成蛋白，特别是在 神经肌肉接头(如果蝇动力素)。序列分析有 揭示了蛋白质的氨基末端高度保守 包括三方共识元素的一半，其特征是 GTP结合蛋白，以及较低的保守度，或NO 完全是保守的，在它们的羧基末端的一半。变种人 分析表明，正是这个羧基末端区域是重要的 用于抗病毒活性。为了了解其作用和演变过程， 这一蛋白质家族，并将其用于抗病毒目的，我们需要 要知道每个Mx蛋白是否执行独特的功能，或者是否 所有Mx蛋白都通过相同的方式执行相似的功能 基本的分子机制。为此，我们开始测试 干扰素诱导的大鼠Mx蛋白与大鼠的功能相似性 动力剂。我们发现，抗病毒活性细胞质和非活性细胞质 在体外，MX蛋白与Dynamin蛋白共同结合微管。 此外，这些蛋白质似乎都不与微管共定位。 在体内，它们可以用洗涤剂从未固定的细胞中提取， 可能是因为它们是膜相关的。因此，Mx蛋白和 Dynamin在体内可能有相似的功能。然而，事实是 抗病毒活性蛋白和非活性蛋白的行为类似于动力素 提示Mx蛋白的抗病毒活性可能是解离的。 从它们的细胞功能。细胞和抗病毒药物的分离 函数也是从一组不同的实验中提出的。什么时候 大鼠细胞质MX2蛋白--一种缺乏抗流感作用的蛋白 活性--发生了突变，现在积累在细胞核中，它 变得活跃起来，抗击流感病毒。研究正在进行中，以 确定Mx蛋白在体内与哪些细胞结构相关， 以及它们如何在分子水平上对抗病毒。

The potent anti-influenza viral activity of the murine intracellular host protein Mxl has stimulated the search for related, potentially antiviral proteins in other organisms. To date, a total of 12 related sequences nave been cloned and some of the respective proteins analyzed. The family of Mx proteins comprises members serving seemingly disparate, including non-antiviral, functions. The following subgroups can be distinguished: 1) interferon-regulated, antiviral proteins (e.g. mouse Mxl, human MxA); 2) interferon-regulated proteins devoid of antiviral activity (e.g. rat Mx3, human MxB); 3) constitutive proteins important for proper exocytotic protein trafficking (e.g. yeast Vps 1); 4) constitutive proteins important in endocytosis, particularly at the neuromuscular junction (e.g. Drosophila dynamin). Sequence analysis has revealed a high degree of conservation of the proteins' amino-terminal halves which include a tripartite consensus element characteristic of GTP-binding proteins, and a lower degree of conservation, or no conservation at all, in their carboxyl-terminal halves. A mutational analysis shows that it is this carboxyl-terminal region that is important for antiviral activity. In order to understand the role and evolution of this family of proteins, and exploit them for antiviral purposes, we need to know whether each Mx protein performs a unique function, or whether all Mx proteins perform similar functions operating through the same basic molecular mechanism. To this end, we began to test interferon-inducible rat Mx proteins for functional similarities with rat dynamin. We found that both antivirally active and inactive cytoplasmic Mx proteins share with dynamin the binding of microtubules in vitro. Furthermore, none of these proteins seems colocalized with microtubules in vivo, and they can be extracted from unfixed cells with detergent, possibly because they are membrane-associated. Thus, Mx proteins and dynamin may share functional similarities in vivo. However, the fact that both antivirally active and inactive proteins behave like dynamin suggests that the antiviral activities of Mx proteins may be dissociated from their cellular functions. A dissociation of cellular and antiviral functions is also suggested from a different set of experiments. When the cytoplasmic rat Mx2 protein--a protein lacking anti-influenza activity--was mutated such that it now accumulated in the nucleus, it became active against influenza virus. Studies are in progress to determine with which cellular structures Mx proteins associate in vivo, and how they act against viruses at the molecular level.