Murine Cytomegalovirus Protein pM79 Is a Key Regulator for Viral Late Transcription
Murine Cytomegalovirus Protein pM79 Is a Key Regulator for Viral Late Transcription
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DOI：
10.1128/jvi.00688-13
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发表时间：
2013-08-01
影响因子：
5.4
通讯作者：
Yu, Dong
中科院分区：
文献类型：
--
作者：
Chapa, Travis J.;Johnson, L. Steven;Yu, Dong
疱疹病毒基因在容许性感染期间暂时表达，但它们的表达在后期是如何调节的，人们知之甚少。先前的研究表明，人类巨细胞病毒（CMV）基因UL79是晚期基因表达所必需的。然而，其作用机制尚未完全阐明，其他cmv中的UL79同源物尚未被研究。在这里，我们描述了保守的小鼠巨细胞病毒（MCMV）基因M79的作用。我们发现M79编码一种蛋白（pM79），该蛋白以早-晚动力学表达，并定位于核病毒复制区室。在没有病毒DNA合成的情况下，M79的转录显著降低，但pM79明显刺激了M79的转录。为了研究其作用，我们创建了重组病毒SMin79，其中pM79的表达被破坏。虽然标记拯救的病毒在成纤维细胞中有效生长，但SMin79不能产生感染性后代，而是通过pM79的反式表达获救。在SMin79感染过程中，有代表性的病毒早、早基因产物和病毒DNA积累充足。病毒复制区室的形成也正常。脉冲场凝胶电泳分析表明，野生型和SMin79感染复制的病毒DNA的整体结构无法区分。病毒瓦片阵列和定量PCR分析显示，pM79突变显著减少了许多对病毒DNA合成抑制剂（膦乙酸）敏感的晚期转录本。这项研究表明，巨细胞病毒在感染后期使用一种保守的机制来促进转录，pM79是至少一部分病毒DNA合成依赖转录物的关键调节因子。
Herpesvirus genes are temporally expressed during permissive infections, but how their expression is regulated at late times is poorly understood. Previous studies indicate that the human cytomegalovirus (CMV) gene, UL79, is required for late gene expression. However, the mechanism remains to be fully elucidated, and UL79 homologues in other CMVs have not been studied. Here, we characterized the role of the conserved murine CMV (MCMV) gene M79. We showed that M79 encoded a protein (pM79) which was expressed with early-late kinetics and localized to nuclear viral replication compartments. M79 transcription was significantly decreased in the absence of viral DNA synthesis but markedly stimulated by pM79. To investigate its role, we created the recombinant virus SMin79, in which pM79 expression was disrupted. While marker-rescued virus grew efficiently in fibroblasts, SMin79 failed to produce infectious progeny but was rescued by pM79 expression in trans. During SMin79 infection, representative viral immediate-early and early gene products as well as viral DNA accumulated sufficiently. Formation of viral replication compartments also appeared normal. Pulsed-field gel electrophoresis analysis indicated that the overall structure of replicating viral DNA was indistinguishable between wild-type and SMin79 infection. Viral tiled array and quantitative PCR analysis revealed that many late transcripts sensitive to a viral DNA synthesis inhibitor (phosphonoacetic acid) were markedly reduced by pM79 mutation. This study indicates that cytomegaloviruses use a conserved mechanism to promote transcription at late stages of infection and that pM79 is a critical regulator for at least a subset of viral DNA synthesis-dependent transcripts.