Herpes Simplex Virus UL12.5 Targets Mitochondria through a Mitochondrial Localization Sequence Proximal to the N Terminus
Herpes Simplex Virus UL12.5 Targets Mitochondria through a Mitochondrial Localization Sequence Proximal to the N Terminus
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DOI：
10.1128/jvi.02087-08
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发表时间：
2009-03-15
影响因子：
5.4
通讯作者：
Smiley, James R.
中科院分区：
文献类型：
--
作者：
Corcoran, Jennifer A.;Saffran, Holly A.;Smiley, James R.
单纯疱疹病毒1型（HSV-1）基因UL 12编码一种保守的碱性DNA酶，在所有疱疹病毒中具有直向同源物。HSV-1 UL 12基因产生两种分别启动的3'共末端mRNA，它们编码不同但相关的蛋白质：全长UL 12和UL12.5，UL12.5是起始于UL 12密码子127的氨基末端截短形式。全长UL 12定位于细胞核，在那里它促进从较大的前体产生成熟的病毒基因组。相比之下，UL12.5主要是线粒体的，并且在感染期间早期起触发线粒体基因组降解的作用。我们研究了这些非常不同的亚细胞定位模式的基础。我们证实了一个早期的报告，全长UL 12的氨基末端区域是核定位所需的，并提供证据表明，多个核定位决定因素存在于该地区。此外，我们证明了UL12.5的线粒体定位在很大程度上依赖于位于UL 12残基185和245之间的序列（UL12.5残基59至119）。该区域包含类似于典型线粒体基质定位信号的序列，并且减少该元件的正电荷的突变严重损害线粒体定位。与基质定位一致，UL12.5显示出与基质蛋白亲环素D不可区分的去污剂提取谱。线粒体DNA消耗需要UL12.5的核酸外切酶活性，这与位于基质内的UL12.5直接破坏线粒体基因组的想法一致。这些结果阐明了两种高度相关的病毒蛋白如何靶向不同的亚细胞位置，具有不同的功能后果。
The herpes simplex virus type 1 (HSV-1) gene UL12 encodes a conserved alkaline DNase with orthologues in all herpesviruses. The HSV-1 UL12 gene gives rise to two separately promoted 3' coterminal mRNAs which encode distinct but related proteins: full-length UL12 and UL12.5, an amino-terminally truncated form that initiates at UL12 codon 127. Full-length UL12 localizes to the nucleus where it promotes the generation of mature viral genomes from larger precursors. In contrast, UL12.5 is predominantly mitochondrial and acts to trigger degradation of the mitochondrial genome early during infection. We examined the basis for these very different subcellular localization patterns. We confirmed an earlier report that the amino-terminal region of full-length UL12 is required for nuclear localization and provide evidence that multiple nuclear localization determinants are present in this region. In addition, we demonstrate that mitochondrial localization of UL12.5 relies largely on sequences located between UL12 residues 185 and 245 (UL12.5 residues 59 to 119). This region contains a sequence that resembles a typical mitochondrial matrix localization signal, and mutations that reduce the positive charge of this element severely impaired mitochondrial localization. Consistent with matrix localization, UL12.5 displayed a detergent extraction profile indistinguishable from that of the matrix protein cyclophilin D. Mitochondrial DNA depletion required the exonuclease activity of UL12.5, consistent with the idea that UL12.5 located within the matrix acts directly to destroy the mitochondrial genome. These results clarify how two highly related viral proteins are targeted to different subcellular locations with distinct functional consequences.