Functional and Structural Characteristics of NY-ESO-1-related HLA A2-restricted Epitopes and the Design of a Novel Immunogenic Analogue

doi:10.1074/jbc.M314066200

Functional and Structural Characteristics of NY-ESO-1-related HLA A2-restricted Epitopes and the Design of a Novel Immunogenic Analogue^*

^‡Protein Crystallography Unit and Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia, ^¶T cell Laboratory, Ludwig Institute for Cancer Research, Austin and Repatriation Medical Centre, Heidelberg, Victoria 3084, Australia, and the ^**Department of Microbiology and Immunology and ^‡‡ImmunoID, University of Melbourne, Parkville, Victoria 3010, Australia

§§ To whom correspondence and reprint requests may be addressed. Tel.: 613-9905-3736; Fax: 613-9905-4699; E-mail: jamie.rossjohn{at}med.monash.edu.au. ¶¶ A C.R. Roper Fellow of the Faculty of Medicine, Dentistry, and Health Science at the University of Melbourne. To whom correspondence and reprint requests may be addressed. Tel.: 613-8344-9911; Fax: 613-9347-1540; E-mail: apurcell{at}unimelb.edu.au.

Abstract

NY-ESO-1, a commonly expressed tumor antigen of the cancer-testis family, is expressed by a wide range of tumors but not found in normal adult somatic tissue, making it an ideal cancer vaccine candidate. Peptides derived from NY-ESO-1 have shown preclinical and clinical trial promise; however, biochemical features of these peptides have complicated their formulation and led to heterogeneous immune responses. We have taken a rational approach to engineer an HLA A2-restricted NY-ESO-1-derived T cell epitope with improved formulation and immunogenicity to the wild type peptide. To accomplish this, we have solved the x-ray crystallographic structures of HLA A2 complexed to NY-ESO (157-165) and two analogues of this peptide in which the C-terminal cysteine residue has been substituted to alanine or serine. Substitution of cysteine by serine maintained peptide conformation yet reduced complex stability, resulting in poor cytotoxic T lymphocyte recognition. Conversely, substitution with alanine maintained complex stability and cytotoxic T lymphocyte recognition. Based on the structures of the three HLA A2 complexes, we incorporated 2-aminoisobutyric acid, an isostereomer of cysteine, into the epitope. This analogue is impervious to oxidative damage, cysteinylation, and dimerization of the peptide epitope upon formulation that is characteristic of the wild type peptide. Therefore, this approach has yielded a potential therapeutic molecule that satiates the hydrophobic F pocket of HLA A2 and exhibited superior immunogenicity relative to the wild type peptide.

Footnotes

↵1 The abbreviations used are: MHC, major histocompatibility complex; Ag, antigen; T_CD8, CD8⁺ T lymphocytes; CTL, cytotoxic T lymphocyte(s); Fmoc, N-(9-fluorenyl)methoxycarbonyl; TAA, tumor-associated antigen(s); Abu, 2-aminoisobutyric acid.
The atomic coordinates and structure factors (codes 1S9W, 1S9X, and 1S9Y) have been deposited in the Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers University, New Brunswick, NJ (http://www.rcsb.org/).
↵* This work was supported by the National Health and Medical Research Council, the Roche Organ Transplantation Research Foundation, and the Juvenile Diabetes Research Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵§ These two authors contributed equally to this work.
↵∥ Supported by Wellcome Trust Senior Research Fellowships in Biomedical Science in Australia.
- Received December 23, 2003.
- Revision received March 2, 2004.
The American Society for Biochemistry and Molecular Biology, Inc.