Influence of translation efficiency of homologous viral proteins on the endogenous presentation of CD8+ T cell epitopes.
A significant proportion of endogenously processed CD8(+) T cell epitopes are derived from newly synthesized proteins and rapidly degrading polypeptides (RDPs). It has been hypothesized that the generation of rapidly degrading polypeptides and CD8(+) T cell epitopes from these RDP precursors may be influenced by the efficiency of protein translation. Here we address this hypothesis by using the Epstein-Barr virus-encoded nuclear antigen 1 protein (EBNA1), with or without its internal glycine-alanine repeat sequence (EBNA1 and EBNA1DeltaGA, respectively), which display distinct differences in translation efficiency. We demonstrate that RDPs constitute a significant proportion of newly synthesized EBNA1 and EBNA1DeltaGA and that the levels of RDPs produced by each of these proteins directly correlate with the translation efficiency of either EBNA1 or EBNA1DeltaGA. As a consequence, a higher number of major histocompatibility complex-peptide complexes can be detected on the surface of cells expressing EBNA1DeltaGA, and these cells are more efficiently recognized by virus-specific cytotoxic T lymphocytes compared to the full-length EBNA1. More importantly, we also demonstrate that the endogenous processing of these CD8(+) T cell epitopes is predominantly determined by the rate at which the RDPs are generated rather than the intracellular turnover of these proteins.
Tellam
Judy
J
Australian Centre for Vaccine Development and Tumour Immunology Laboratory, Division of Infectious Diseases and Immunology, Clive Berghofer Cancer Research Centre, Queensland Institute of Medical Research, Brisbane (Qld) 4006, Australia.
Fogg
Mark H
MH
Rist
Michael
M
Connolly
Geoff
G
Tscharke
David
D
Webb
Natasha
N
Heslop
Lea
L
Wang
Fred
F
Khanna
Rajiv
R
D017951:Antigen Presentation / Q000235:genetics / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D002460:Cell Line; D002461:Cell Line, Transformed; D004151:Dipeptides / Q000235:genetics; D018984:Epitopes, T-Lymphocyte / Q000276:immunology* / Q000378:metabolism*; D019309:Epstein-Barr Virus Nuclear Antigens / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
D004151:Dipeptides; D018984:Epitopes, T-Lymphocyte; D019309:Epstein-Barr Virus Nuclear Antigens; C065992:N-glycylalanine; C417029:EBV-encoded nuclear antigen 1