Negative regulation of a heterologous promoter by human cytomegalovirus immediate-early protein IE2.
The HCMV IE2 protein promiscuously activates transcription of many viral and cellular genes. IE2 also negatively autoregulates its own expression by binding to a strategically positioned IE2 binding site, called CRS, located immediately downstream of the TATA box of the HCMV major IE promoter. Here we show that IE2 is able to repress transcription driven by a heterologous promoter, RSV LTR. Repression of RSV LTR by IE2 is completely dependent of DNA sequences downstream of the TATA box of RSV LTR. A DNA sequence, 5'-CGATACAATAAACG-3', evidently matching the proposed CRS consensus sequence, is located between nucleotides -13 and +1 (relative to the transcription start site) of RSV LTR. Three lines of evidence support the notion that this RSV CRS element is involved in the IE2-mediated repression of RSV LTR. First, introduction of mutation to the RSV CRS element renders to the mutant RSV LTR resistance to IE2-mediated repression. Second, a mutant IE2 defective in DNA binding cannot downregulate transcription from RSV LTR. Third, IE2 specifically binds to the wild-type, but not the mutant, RSV CRS element in vitro. These data, in conjunction with previous works, demonstrate that IE2 can passively repress transcription of homologous and heterologous promoters that contain a CRS element.
Tsai
H L
HL
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Kou
G H
GH
Tang
F M
FM
Wu
C W
CW
Lin
Y S
YS
D002460:Cell Line; D003587:Cytomegalovirus / Q000235:genetics / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D006367:HeLa Cells; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000502:physiology*; D008562:Membrane Glycoproteins; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D018113:Respiratory Syncytial Virus, Human / Q000235:genetics*; D016385:TATA Box; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D014759:Viral Envelope Proteins; D014764:Viral Proteins
C069186:IE2 protein, Cytomegalovirus; D017874:Immediate-Early Proteins; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; 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