Dataset Information

Viral immune evasions differentially impact cell surface presentation of MHC I allomorphs already at the peptide-loading complex

ABSTRACT: The transporter associated with antigen processing (TAP) translocates peptides from the cytosol into the endoplasmic reticulum (ER) where they are loaded onto major histocompatibility class I (MHC I) molecules. Stable peptide-MHC I complexes travel to the cell surface and present their antigenic cargo to cytotoxic T lymphocytes. As central part of the peptide-loading complex (PLC), TAP is targeted by several viral proteins, which inhibit peptide translocation and thereby impact MHC I-mediated immune responses. However, it is still poorly understood whether the MHC I allotypes are differently affected by TAP inhibition. Here, we show that conditional expression of herpes simplex virus (HSV) ICP47 suppresses surface presentation of the MHC I allotypes HLA-A and HLA-C, but not of HLA-B, while expression of cytomegalovirus (CMV) US6 reduces surface levels of all allotypes. This difference is directly reflected in a specific enrichment of HLA-B molecules at US6 arrested PLC. Since ICP47 and US6 inhibit TAP in different transport-incompetent conformations, our data imply that MHC I allomorphs are preferentially recruited or trapped at the PLC leading to selective downregulation of MHC I surface presentation. Our findings suggest that viral immune evasions not only inhibit peptide supply to the ER by TAP, but also modulate the assembly and chaperone activity of the PLC.

INSTRUMENT(S): Q Exactive Plus

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Marie Alfes

LAB HEAD: Carla Schmidt

PROVIDER: PXD027408 | Pride | 2022-02-17

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	20191218_MB_PLC_ICP47.raw	Raw
	20191218_MB_PLC_US6.raw	Raw
	20200508_MB_PLC_ICP47_R2.raw	Raw
	20200508_MB_PLC_US6_R2.raw	Raw
	20201023_PLC_ICP47_R3.raw	Raw

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Publications

Viral immune evasins impact antigen presentation by allele-specific trapping of MHC I at the peptide-loading complex.

Sethumadhavan Sunesh S Barth Marie M Spaapen Robbert M RM Schmidt Carla C Trowitzsch Simon S Tampé Robert R

Scientific reports 20220127 1

Major histocompatibility complex class I (MHC I) molecules present antigenic peptides to cytotoxic T cells to eliminate infected or cancerous cells. The transporter associated with antigen processing (TAP) shuttles proteasomally generated peptides into the ER for MHC I loading. As central part of the peptide-loading complex (PLC), TAP is targeted by viral factors, which inhibit peptide supply and thereby impact MHC I-mediated immune responses. However, it is still poorly understood how antigen p ...[more]

PMID: 35087068

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Project description:The majority of peptides presented by MHC class I results from proteasomal protein turnover. The specialized immunoproteasome, which is induced during inflammation, plays a major role in antigenic peptide generation. However, other cellular proteases can, either alone or together with the proteasome, contribute peptides for MHC class I loading non-canonically. We used an im-munopeptidomics workflow combined with a prediction software for proteasomal cleavage probabilities to analyze how inflammatory conditions affect proteasomal processing of immune epitopes presented by A549 cells. Treatment of A549 cells with IFNγ enhanced proteasomal cleavage probability of MHC class I ligands for both, the constitutive proteasome and the im-munoproteasome. Furthermore, IFNγ alters the contribution of the different HLA allotypes to the immunopeptidome. When we calculated HLA allotype-specific proteasomal cleavage probabili-ties for MHC class I ligands, peptides presented by HLA-A*30:01 showed characteristics hinting at a reduced C-terminal proteasomal cleavage probability independently of the type of proteasome. This was confirmed by HLA-A*30:01 ligands from the immune epitope database, which also showed this effect. Furthermore, two additional HLA allotypes, namely HLA-A*03:01 and HLA-A*11:01, presented peptides with a markedly reduced C-terminal proteasomal cleavage probability. Peptides eluted from all three HLA allotypes shared a peptide binding motif with a C-terminal lysine residue suggesting that this lysine residue impairs proteasome-dependent HLA ligand production and might, in turn, favor peptide generation by other cellular proteases. The mass spectrometry raw files used in this study were originally produced for a previous publication, where they were utilized to address the influence of cigarette smoke on the antiviral T-cell immune response. Here, we have reanalyzed the data to investigate processing of MHC class I ligands by c20S or i20S, respectively. Original publication: Chen, J.; Wang, X.; Schmalen, A.; Haines, S.; Wolff, M.; Ma, H.; Zhang, H.; Stoleriu, M.G.; Nowak, J.; Nakayama, M.; et al. Antiviral CD8(+) T cell immune responses are impaired by cigarette smoke and in COPD. Eur Respir J 2023, doi:10.1183/13993003.01374-2022.