Lee Hye-Ra, Huh Yong Ho, Kim Young-Eui, Lee Karim, Kim Sunyoung, Ahn Jin-Hyun
Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Jangangu, Suwon, Gyeonggido 440-746, Republic of Korea.
Biochem Biophys Res Commun. 2007 May 4;356(2):499-504. doi: 10.1016/j.bbrc.2007.03.007. Epub 2007 Mar 8.
The 72-kDa IE1 protein of human cytomegalovirus disrupts PML-associated subnuclear structures (PODs) by inducing PML desumoylation. This process correlates with the functions of IE1 in transcriptional regulation and efficient viral replication. Here, we defined the N-terminal regions of IE1 required for nuclear targeting and POD-disrupting activity. Although the 24 N-terminal amino acids encoded by exon 2, which were previously shown to be essential for nuclear targeting, did not appear to contain typical basic nuclear localization signals, these residues were able to efficiently convey the GFP protein into the nucleus, suggesting a role in promoting nuclear translocation. In assays using a series of N-terminal truncation IE1 mutants, which were forced to enter the nucleus, exon 2 was completely dispensable for POD disruption. However, the predicted two alpha-helix regions in exon 3 were identified as important structural determinants for protein stability and for the correlating activities in POD disruption and PML desumoylation.
人巨细胞病毒的72-kDa IE1蛋白通过诱导PML去SUMO化来破坏与PML相关的亚核结构（PODs）。这一过程与IE1在转录调控和高效病毒复制中的功能相关。在此，我们确定了IE1的核靶向和破坏POD活性所需的N端区域。尽管外显子2编码的24个N端氨基酸先前被证明对核靶向至关重要，但它们似乎不包含典型的碱性核定位信号，这些残基能够有效地将GFP蛋白转运到细胞核中，表明其在促进核转运中发挥作用。在使用一系列被迫进入细胞核的N端截短IE1突变体的实验中，外显子2对于破坏POD完全是可有可无的。然而，外显子3中预测的两个α螺旋区域被确定为蛋白质稳定性以及POD破坏和PML去SUMO化相关活性的重要结构决定因素。
