The murine cytomegalovirus immunoevasin m152/gp40 binds major histocompatibility complex (MHC) class I molecules and retains them in the early secretory pathway by a previously unknown mechanism, preventing antigen presentation to CD8+ T cells. We show that retention of class I and of gp40 itself depends on a lumenal linker sequence in gp40. With unbiased co-immunoprecipitation and mass spectrometry, we find that, through this linker, gp40 binds to TMED10/Tmp21/p24δ1, a member of the p24 family of endoplasmic reticulum (ER)/Golgi transmembrane proteins. We show that the C-terminal KKxxx Golgi-to-ER retrieval signal of TMED10 is required for gp40-mediated retention of class I. We thus identify a viral interaction partner of the p24 proteins and their exploitation for viral immune evasion.
Keywords: MHC class I; NKG2D ligand; gp40; immune evasion; m152; murine cytomegalovirus; p24 family.
Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.