| Author |
Koorengevel, Martijn Neefjes, Jacques J. Killian, Antoinette Ressing, Maaike E. Hoelen, Hanneke Früh, Klaus Wiertz, Emmanuel J. H. J. Kruse, Elisabeth Luteijn, Rutger D. Grootens, Jennine Horst, Daniëlle Van Leeuwen, Wouter F. Kremmer, Elisabeth Drijfhout, Jan W. Lebbink, Robert Jan |
| Description |
Author Affiliation: Luteijn RD ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); Hoelen H ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); Kruse E ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); van Leeuwen WF ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); Grootens J ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); Horst D ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); Koorengevel M ( Department of Membrane Biochemistry and Biophysics, Utrecht University, 3584 CH Utrecht, the Netherlands); Drijfhout JW ( Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands); Kremmer E ( Helmholtz Center Munich, German Research Center for Environmental Health, Institute of Molecular Immunology, 81377 Munich, Germany); Früh K ( Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, OR 97006); Neefjes JJ ( Department of Cell Biology, The Netherlands Cancer Institute, 1066 CX Amsterdam, the Netherlands.); Killian A ( Department of Membrane Biochemistry and Biophysics, Utrecht University, 3584 CH Utrecht, the Netherlands); Lebbink RJ ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); Ressing ME ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands); Wiertz EJ ( Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands) |
| Abstract |
CD8(+) CTLs detect virus-infected cells through recognition of virus-derived peptides presented at the cell surface by MHC class I molecules. The cowpox virus protein CPXV012 deprives the endoplasmic reticulum (ER) lumen of peptides for loading onto newly synthesized MHC class I molecules by inhibiting the transporter associated with Ag processing (TAP). This evasion strategy allows the virus to avoid detection by the immune system. In this article, we show that CPXV012, a 9-kDa type II transmembrane protein, prevents peptide transport by inhibiting ATP binding to TAP. We identified a segment within the ER-luminal domain of CPXV012 that imposes the block in peptide transport by TAP. Biophysical studies show that this domain has a strong affinity for phospholipids that are also abundant in the ER membrane. We discuss these findings in an evolutionary context and show that a frameshift deletion in the CPXV012 gene in an ancestral cowpox virus created the current form of CPXV012 that is capable of inhibiting TAP. In conclusion, our findings indicate that the ER-luminal domain of CPXV012 inserts into the ER membrane, where it interacts with TAP. CPXV012 presumably induces a conformational arrest that precludes ATP binding to TAP and, thus, activity of TAP, thereby preventing the presentation of viral peptides to CTLs. |
