From the Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio 43210 and.
Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, New York 10065.
J Biol Chem. 2017 Dec 29;292(52):21517-21526. doi: 10.1074/jbc.M117.800482. Epub 2017 Oct 27.
Interferon-induced transmembrane protein 3 (IFITM3) is a cellular endosome- and lysosome-localized protein that restricts numerous virus infections. IFITM3 is activated by palmitoylation, a lipid posttranslational modification. Palmitoylation of proteins is primarily mediated by zinc finger DHHC domain-containing palmitoyltransferases (ZDHHCs), but which members of this enzyme family can modify IFITM3 is not known. Here, we screened a library of human cell lines individually lacking ZDHHCs 1-24 and found that IFITM3 palmitoylation and its inhibition of influenza virus infection remained strong in the absence of any single ZDHHC, suggesting functional redundancy of these enzymes in the IFITM3-mediated antiviral response. In an overexpression screen with 23 mammalian ZDHHCs, we unexpectedly observed that more than half of the ZDHHCs were capable of increasing IFITM3 palmitoylation with ZDHHCs 3, 7, 15, and 20 having the greatest effect. Among these four enzymes, ZDHHC20 uniquely increased IFITM3 antiviral activity when both proteins were overexpressed. ZDHHC20 colocalized extensively with IFITM3 at lysosomes unlike ZDHHCs 3, 7, and 15, which showed a defined perinuclear localization pattern, suggesting that the location at which IFITM3 is palmitoylated may influence its activity. Unlike knock-out of individual ZDHHCs, siRNA-mediated knockdown of both ZDHHC3 and ZDHHC7 in ZDHHC20 knock-out cells decreased endogenous IFITM3 palmitoylation. Overall, our results demonstrate that multiple ZDHHCs can palmitoylate IFITM3 to ensure a robust antiviral response and that ZDHHC20 may serve as a particularly useful tool for understanding and enhancing IFITM3 activity.
干扰素诱导跨膜蛋白 3（IFITM3）是一种细胞内体和溶酶体定位的蛋白质，可限制多种病毒感染。IFITM3 通过棕榈酰化激活，这是一种脂质翻译后修饰。蛋白质的棕榈酰化主要由锌指 DHHC 结构域含有棕榈酰转移酶（ZDHHC）介导，但该酶家族的哪些成员可以修饰 IFITM3 尚不清楚。在这里，我们筛选了一组单独缺乏 ZDHHC1-24 的人细胞系文库，发现 IFITM3 棕榈酰化及其对流感病毒感染的抑制作用在没有任何单个 ZDHHC 的情况下仍然很强，这表明这些酶在 IFITM3 介导的抗病毒反应中具有功能冗余性。在一个包含 23 种哺乳动物 ZDHHC 的过表达筛选中，我们出人意料地观察到超过一半的 ZDHHC 能够增加 IFITM3 的棕榈酰化，其中 ZDHHC3、7、15 和 20 的效果最大。在这四种酶中，当两种蛋白质都过表达时，ZDHHC20 独特地增加了 IFITM3 的抗病毒活性。ZDHHC20 与 IFITM3 在溶酶体中广泛共定位，而不像 ZDHHC3、7 和 15，它们显示出明确的核周定位模式，这表明 IFITM3 被棕榈酰化的位置可能影响其活性。与单个 ZDHHC 的敲除不同，在 ZDHHC20 敲除细胞中 siRNA 介导的 ZDHHC3 和 ZDHHC7 的敲低均降低了内源性 IFITM3 的棕榈酰化。总的来说，我们的结果表明，多种 ZDHHC 可以棕榈酰化 IFITM3，以确保强大的抗病毒反应，并且 ZDHHC20 可能是理解和增强 IFITM3 活性的有用工具。
