Molecular mechanism and species specificity of TAP inhibition by herpes simplex virus protein ICP47

Kwaangseog Ahn, Thomas H. Meyer, Stephan Uebel, Pascal Sempé, Hakim Djaballah, Young Yang, Per A. Peterson, Klaus Früh, Robert Tampé

Research output: Contribution to journalArticlepeer-review

284 Scopus citations


The immediate early protein ICP47 of herpes simplex virus (HSV) inhibits the transporter for antigen processing (TAP)-mediated translocation of antigen-derived peptides across the endoplasmic reticulum (ER) membrane. This interference prevents assembly of peptides with class I MHC molecules in the ER and ultimately recognition of HSV-infected cells by cytotoxic T-lymphocytes, potentially leading to immune evasion of the virus. Here, we demonstrate that recombinant, purified ICP47 containing a hexahistidine tag inhibits peptide import into microsomes of insect cells expressing human TAP, whereas inhibition of peptide transport by murine TAP was much less effective. This finding indicates an intrinsic species-specificity of ICP47 and suggests that no additional proteins interacting specifically with either ICP47 or TAP are required for inhibition of peptide transport. Since neither purified nor induced ICP47 inhibited photo-crosslinking of 8-azido-ATP to TAP1 and TAP2 it seems that ICP47 does not prevent ATP from binding to TAP. By contrast, peptide binding was completely blocked by ICP47 as shown both by photoaffinity crosslinking of peptides to TAP and peptide binding to microsomes from TAP-transfected insect cells. Competition experiments indicated that ICP47 binds to human TAP with a higher affinity (50 nM) than peptides whereas the affinity to murine TAP was 100-fold lower. Our data suggest that ICP47 prevents peptides from being translocated by blocking their binding to the substrate-binding site of TAP.

Original languageEnglish (US)
Pages (from-to)3247-3255
Number of pages9
JournalEMBO Journal
Issue number13
StatePublished - Jul 1 1996
Externally publishedYes


  • ABC-transporter
  • Antigen presentation
  • Antigen processing
  • Herpes simplex
  • Immune evasion

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)


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