Phosphorylation of human cytomegalovirus glycoprotein B (gB) at the acidic cluster casein kinase 2 site (Ser900) is required for localization of gB to the trans-Golgi network and efficient virus replication.
Phosphorylation of human cytomegalovirus glycoprotein B (gB) at the acidic cluster casein kinase 2 site (Ser900) is required for localization of gB to the trans-Golgi network and efficient virus replication.
复制标题
人巨细胞病毒糖蛋白 B (gB) 在酸性簇酪蛋白激酶 2 位点 (Ser900) 的磷酸化是 gB 定位到跨高尔基体网络和有效病毒复制所必需的。
DOI：
10.1128/jvi.78.1.285-293.2004
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发表时间：
2004
影响因子：
5.4
通讯作者：
Baldick,CarlJ
中科院分区：
文献类型：
--
作者：
Jarvis,MichaelA;Jones,ThomasR;Drummond,DerekD;Smith,PatsyP;Britt,WilliamJ;Nelson,JayA;Baldick,CarlJ
人巨细胞病毒（HCMV）糖蛋白B （gB）由UL55开放阅读框编码，是参与细胞附着和进入的重要包膜糖蛋白。在此之前，我们发现残基丝氨酸900 （Ser900）是HCMV gB细胞质结构域中可逆酪蛋白激酶2磷酸化的一个独特位点。我们最近还发现，在hcmv允许细胞中，gB定位于反式高尔基网络（TGN），从而确定TGN可能是病毒包膜的一个位点。当前研究的目的是确定ser900磷酸化在gB转运到TGN和HCMV生物发生中的作用。构建重组HCMV菌株，表达含有天冬氨酸（gBAsp900）或丙氨酸残基（gBAla900）取代的gB分子，分别模拟磷酸化或非磷酸化形式。免疫荧光分析显示，gbasp900在感染HCMV重组病毒的成纤维细胞中被定位在TGN上。相比之下，gbala900从TGN中部分错定位，表明gB在ser900处的磷酸化是TGN定位所必需的。gbasp900的TGN定位增加是由于分子转运到后TGN区室的减少。值得注意的是，在HCMV感染成纤维细胞期间，用天冬氨酸残基代替ser900也导致子代病毒产生水平的增加。总之，这些结果表明，gB在ser900处的磷酸化对于gB定位到TGN以及有效的病毒复制是必要的，并进一步支持TGN作为HCMV包膜的一个位点。
Human cytomegalovirus (HCMV) glycoprotein B (gB), encoded by the UL55 open reading frame, is an essential envelope glycoprotein involved in cell attachment and entry. Previously, we identified residue serine 900 (Ser900) as a unique site of reversible casein kinase 2 phosphorylation in the cytoplasmic domain of HCMV gB. We have also recently shown that gB is localized to thetrans-Golgi network (TGN) in HCMV-permissive cells, thereby identifying the TGN as a possible site of virus envelopment. The aim of the current study was to determine the role of Ser900phosphorylation in transport of gB to the TGN and in HCMV biogenesis. Recombinant HCMV strains were constructed that expressed gB molecules containing either an aspartic acid (gBAsp900) or alanine residue (gBAla900) substitution at Ser900to mimic the phosphorylated or nonphosphorylated form, respectively. Immunofluorescence analysis of the trafficking of gB mutant molecules in fibroblasts infected with the HCMV recombinants revealed that gBAsp900was localized to the TGN. In contrast, gBAla900was partially mislocalized from the TGN, indicating that phosphorylation of gB at Ser900was necessary for TGN localization. The increased TGN localization of gBAsp900was due to a decreased transport of the molecule to post-TGN compartments. Remarkably, the substitution of an aspartic acid residue for Ser900also resulted in an increase in levels of progeny virus production during HCMV infection of fibroblasts. Together, these results demonstrate that phosphorylation of gB at Ser900is necessary for gB localization to the TGN, as well as for efficient viral replication, and further support the TGN as a site of HCMV envelopment.