White Elizabeth A, Spector Deborah H
Dept. of Cellular and Molecular Medicine, Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA.
J Virol. 2005 Jun;79(12):7438-52. doi: 10.1128/JVI.79.12.7438-7452.2005.
The human cytomegalovirus (HCMV) major immediate-early (IE) proteins share an 85-amino-acid N-terminal domain specified by exons 2 and 3 of the major IE region, UL122-123. We have constructed IE Delta30-77, a recombinant virus that lacks the majority of IE exon 3 and consequently expresses smaller forms of both IE1 72- and IE2 86-kDa proteins. The mutant virus is viable but growth impaired at both high and low multiplicities of infection and exhibits a kinetic defect that is not rescued by growth in fibroblasts expressing IE1 72-kDa protein. The kinetics of mutant IE2 protein accumulation in IE Delta30-77 virus-infected cells are approximately normal compared to wild-type virus-infected cells, but the IE Delta30-77 virus is delayed in expression of early viral genes, including UL112-113 and UL44, and does not sustain expression of mutant IE1 protein as the infection progresses. Additionally, cells infected with IE Delta30-77 exhibit altered expression of cellular proteins compared to wild-type HCMV-infected cells. PML is not dispersed but is retained at ND10 sites following infection with IE Delta30-77 mutant virus. While the deletion mutant retains the ability to mediate the stabilization of cyclin B1, cdc6, and geminin in infected cells, its capacity to upregulate the expression of cyclin E has been reduced. These data indicate that the activity of one or both of the HCMV major IE proteins is required in vivo for the modulation of cell cycle proteins observed in cells infected with wild-type HCMV.
人巨细胞病毒（HCMV）主要立即早期（IE）蛋白共享一个由主要IE区域UL122 - 123的外显子2和3指定的85个氨基酸的N端结构域。我们构建了IE Delta30 - 77，一种重组病毒，它缺乏大部分IE外显子3，因此表达较小形式的IE1 72 kDa和IE2 86 kDa蛋白。该突变病毒是有活力的，但在高和低感染复数下生长均受损，并表现出一种动力学缺陷，这种缺陷不能通过在表达IE1 72 kDa蛋白的成纤维细胞中生长来挽救。与野生型病毒感染的细胞相比，IE Delta30 - 77病毒感染的细胞中突变型IE2蛋白积累的动力学大致正常，但IE Delta30 - 77病毒在早期病毒基因（包括UL112 - 113和UL44）的表达上延迟，并且随着感染的进展不能维持突变型IE1蛋白的表达。此外，与野生型HCMV感染的细胞相比，IE Delta30 - 77感染的细胞表现出细胞蛋白表达的改变。感染IE Delta30 - 77突变病毒后，PML没有分散，而是保留在ND10位点。虽然缺失突变体保留了在感染细胞中介导细胞周期蛋白B1、cdc6和geminin稳定的能力，但其上调细胞周期蛋白E表达的能力已降低。这些数据表明，在体内，HCMV主要IE蛋白中的一种或两种的活性是调节野生型HCMV感染细胞中观察到的细胞周期蛋白所必需的。
