CpG-methylation regulates a class of Epstein-Barr virus promoters

PLoS Pathog. 2010 Sep 23;6(9):e1001114. doi: 10.1371/journal.ppat.1001114.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • B-Lymphocytes / pathology
  • B-Lymphocytes / virology
  • Blotting, Western
  • Cells, Cultured
  • Chromatin Immunoprecipitation
  • CpG Islands / genetics*
  • DNA Methylation*
  • DNA, Viral / genetics
  • DNA, Viral / metabolism
  • Electrophoretic Mobility Shift Assay
  • Epigenesis, Genetic*
  • Epstein-Barr Virus Infections / genetics
  • Epstein-Barr Virus Infections / pathology
  • Epstein-Barr Virus Infections / virology
  • Gene Expression Regulation, Viral*
  • Genes, Viral
  • Herpesvirus 4, Human / physiology
  • Humans
  • Immunoprecipitation
  • Kidney / cytology
  • Kidney / metabolism
  • Kidney / virology
  • Luciferases / metabolism
  • Promoter Regions, Genetic / genetics*
  • RNA, Messenger / genetics
  • Response Elements / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Trans-Activators / genetics*
  • Trans-Activators / metabolism
  • Transcription Factor AP-1 / metabolism
  • Virus Latency / genetics*
  • Virus Replication


  • BZLF1 protein, Herpesvirus 4, Human
  • DNA, Viral
  • RNA, Messenger
  • Trans-Activators
  • Transcription Factor AP-1
  • Luciferases