Antagonism between members of the CNC-bZIP family and the immediate-early protein IE2 of human cytomegalovirus.
The HCMV IE2 protein negatively autoregulates its own expression as well as represses the transactivation activity of p53. Using the repression domain of IE2 as bait in the yeast two-hybrid system, Nrf1 and Nrf2, members of the CNC-bZIP family, were found to be IE2-interacting proteins. Residues 331-448 encompassing the DNA-binding and the dimerization domains of Nrf1 are sufficient for the interaction. The interaction was further confirmed in vitro by a glutathione S-transferase pull-down assay and in vivo by co-immunoprecipitation. In transient transfection studies, transcription driven by six copies of an NF-E2 site or by chimeric proteins between the DNA-binding domain of LexA and members of the CNC-bZIP family is repressed by IE2. Importantly, the DNA binding activity of the Nrf1/MafK heterodimer is not impeded by IE2. In a parallel study, CNC-bZIP factors attenuate the negative autoregulation of IE2. The attenuation could be explained by the finding that Nrf1 functions alone and synergistically with its heterodimerization partner, MafK, in inhibiting the DNA binding activity of IE2. Taken together, these results demonstrate the existence of antagonism between members of the CNC-bZIP family and IE2.
Huang
C F
CF
Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
Wang
Y C
YC
Tsao
D A
DA
Tung
S F
SF
Lin
Y S
YS
Wu
C W
CW
D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D015723:Gene Library; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D016350:Leucine Zippers; D050985:MafK Transcription Factor; D008562:Membrane Glycoproteins; D051267:NF-E2-Related Factor 2; D009687:Nuclear Proteins / Q000378:metabolism*; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; D010449:Peptide Mapping; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection; D014759:Viral Envelope Proteins; D014764:Viral Proteins
D004268:DNA-Binding Proteins; C069186:IE2 protein, Cytomegalovirus; D017874:Immediate-Early Proteins; D050985:MafK Transcription Factor; D008562:Membrane Glycoproteins; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C495633:NRF1 protein, human; D009687:Nuclear Proteins; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; D015534:Trans-Activators; C077406:UL115 protein, Human herpesvirus 5; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C071440:glycoprotein H, Cytomegalovirus; C499358:glycoprotein H, Human cytomegalovirus; C439068:glycoprotein O, cytomegalovirus; D004247:DNA