CpG-methylation regulates a class of Epstein-Barr virus promoters.
DNA methylation is the major modification of eukaryotic genomes and plays an essential role in mammalian gene regulation. In general, cytosine-phosphatidyl-guanosine (CpG)-methylated promoters are transcriptionally repressed and nuclear proteins such as MECP2, MBD1, MBD2, and MBD4 bind CpG-methylated DNA and contribute to epigenetic silencing. Methylation of viral DNA also regulates gene expression of Epstein-Barr virus (EBV), which is a model of herpes virus latency. In latently infected human B cells, the viral DNA is CpG-methylated, the majority of viral genes is repressed and virus synthesis is therefore abrogated. EBV's BZLF1 encodes a transcription factor of the AP-1 family (Zta) and is the master gene to overcome viral gene repression. In a genome-wide screen, we now identify and characterize those viral genes, which Zta regulates. Among them are genes essential for EBV's lytic phase, which paradoxically depend on strictly CpG-methylated promoters for their Zta-induced expression. We identified novel DNA recognition motifs, termed meZRE (methyl-Zta-responsive element), which Zta selectively binds in order to 'read' DNA in a methylation- and sequence-dependent manner unlike any other known protein. Zta is a homodimer but its binding characteristics to meZREs suggest a sequential, non-palindromic and bipartite DNA recognition element, which confers superior DNA binding compared to CpG-free ZREs. Our findings indicate that Zta has evolved to transactivate cytosine-methylated, hence repressed, silent promoters as a rule to overcome epigenetic silencing.
Bergbauer
Martin
M
Department of Gene Vectors, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich, Germany.
Kalla
Markus
M
Schmeinck
Anne
A
Göbel
Christine
C
Rothbauer
Ulrich
U
Eck
Sebastian
S
Benet-Pagès
Anna
A
Strom
Tim M
TM
Hammerschmidt
Wolfgang
W
D001402:B-Lymphocytes / Q000473:pathology / Q000821:virology; D015153:Blotting, Western; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D044127:Epigenesis, Genetic; D020031:Epstein-Barr Virus Infections / Q000235:genetics / Q000473:pathology / Q000821:virology; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D004854:Herpesvirus 4, Human / Q000502:physiology; D006801:Humans; D047468:Immunoprecipitation; D007668:Kidney / Q000166:cytology / Q000378:metabolism / Q000821:virology; D008156:Luciferases / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D017735:Virus Latency / Q000235:genetics*; D014779:Virus Replication
C063676:BZLF1 protein, Herpesvirus 4, Human; D004279:DNA, Viral; D012333:RNA, Messenger; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D008156:Luciferases