Ito Hanako, Bando Hisanori, Shimada Toru, Katsuma Susumu
Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Laboratory of Applied Molecular Entomology, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
Biochem Biophys Res Commun. 2014 Nov 28;454(4):581-7. doi: 10.1016/j.bbrc.2014.10.132. Epub 2014 Nov 1.
The baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV) possesses two genes, iap1 and iap2, which encode inhibitor of apoptosis (IAP) proteins. We previously showed that although both genes are dispensable for viral propagation, iap2 is required for efficient viral propagation in cultured cells. BmNPV IAP2 contains three putative functional domains: a baculovirus IAP repeat (BIR), a BIR-like (BIRL) domain, and a RING finger domain. To identify the domain affecting viral growth, we generated a series of BmNPV bacmids expressing iap2 derivatives lacking one or two domains, or possessing a single amino acid substitution to abolish IAP2 ubiquitin ligase activity. We examined their properties in both cultured cells and B. mori larvae. We found that either the BIR or BIRL domain of IAP2 plays an important role in BmNPV infection, and that the RING finger domain, which is required for ubiquitin ligase activity, does not greatly contribute to BmNPV propagation. This is the first study to identify functional domains of the baculovirus IAP2 protein.
杆状病毒家蚕核型多角体病毒（BmNPV）拥有两个基因，即iap1和iap2，它们编码凋亡抑制蛋白（IAP）。我们之前表明，尽管这两个基因对于病毒增殖并非必需，但iap2是病毒在培养细胞中高效增殖所必需的。BmNPV IAP2包含三个假定的功能域：一个杆状病毒IAP重复序列（BIR）、一个类BIR（BIRL）结构域和一个环指结构域。为了确定影响病毒生长的结构域，我们构建了一系列表达iap2衍生物的BmNPV杆粒，这些衍生物缺失一个或两个结构域，或者具有单个氨基酸取代以消除IAP2泛素连接酶活性。我们在培养细胞和家蚕幼虫中检测了它们的特性。我们发现，IAP2的BIR或BIRL结构域在BmNPV感染中起重要作用，而泛素连接酶活性所需的环指结构域对BmNPV增殖的贡献不大。这是首次鉴定杆状病毒IAP2蛋白功能结构域的研究。
