Garvey Tara, Bertin John, Siegel Richard, Lenardo Michael, Cohen Jeffrey
Medical Virology Section, Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-1888, USA.
Virology. 2002 Sep 1;300(2):217-25. doi: 10.1006/viro.2002.1518.
The molluscum contagiosum virus (MCV) MC159 protein contains two death effector domains (DEDs) that bind to the DEDs of caspase-8 and FADD and inhibit apoptosis. We constructed MC159 truncation mutants and found that the amino-terminal region before the first DED and nearly all the carboxyl terminus after the second DED were dispensable for the antiapoptotic activity of MC159. We also engineered tandem repeats of two identical MC159 DEDs, MC159 DEDs in the reverse orientation, and MC159-caspase-8 chimeras in which a DED of MC159 was replaced with the corresponding DED of caspase-8. Each of these constructs bound to caspase-8, but was unable to bind to FADD or block apoptosis. In addition, we constructed mutants containing only a single DED of MC159. These mutants bound to both FADD and caspase-8, but could not block apoptosis or the formation of death effector filaments. Thus, the DEDs of MC159 are not functionally interchangeable with each other or with those of caspase-8.
传染性软疣病毒（MCV）的MC159蛋白含有两个死亡效应结构域（DED），它们与半胱天冬酶-8（caspase-8）和Fas相关死亡结构域蛋白（FADD）的DED结合并抑制细胞凋亡。我们构建了MC159截短突变体，发现第一个DED之前的氨基末端区域以及第二个DED之后几乎所有的羧基末端区域对于MC159的抗凋亡活性都是可有可无的。我们还构建了两个相同的MC159 DED的串联重复序列、反向的MC159 DED以及MC159-半胱天冬酶-8嵌合体，其中MC159的一个DED被半胱天冬酶-8的相应DED取代。这些构建体中的每一个都能与半胱天冬酶-8结合，但不能与FADD结合或阻断细胞凋亡。此外，我们构建了仅含有单个MC159 DED的突变体。这些突变体既能与FADD结合，也能与半胱天冬酶-8结合，但不能阻断细胞凋亡或死亡效应丝的形成。因此，MC159的DED在功能上彼此之间或与半胱天冬酶-8的DED都不可互换。
