N-terminal determinants of human cytomegalovirus IE1 protein in nuclear targeting and disrupting PML-associated subnuclear structures.
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.
Lee
Hye-Ra
HR
Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Jangangu, Suwon, Gyeonggido 440-746, Republic of Korea.
Huh
Yong Ho
YH
Kim
Young-Eui
YE
Lee
Karim
K
Kim
Sunyoung
S
Ahn
Jin-Hyun
JH
D002467:Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D005091:Exons / Q000502:physiology; D006801:Humans; D017874:Immediate-Early Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D009363:Neoplasm Proteins / Q000502:physiology*; D019913:Nuclear Localization Signals / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology*; D000071156:Promyelocytic Leukemia Protein; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology*; D025842:SUMO-1 Protein / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000502:physiology*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
C088645:IE1 protein, cytomegalovirus; D017874:Immediate-Early Proteins; D009363:Neoplasm Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D025842:SUMO-1 Protein; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D014764:Viral Proteins; C070576:PML protein, human