6EWO

Crystal structure of non-phosphorylated form of RTF PHOSPHOPEPTIDE BOUND TO HLA-A2 in complex with LILRB1

Summary for 6EWO

• Entry DOI: 10.2210/pdb6ewo/pdb
• Descriptor: HLA class I histocompatibility antigen, A-2 alpha chain, Beta-2-microglobulin, Synemin, ... (5 entities in total)
• Functional Keywords: lilrb1, nonphosphopeptide, peptide-mhc complex, hla-a2, tumour antigen, crystallisation chaperone, immune system
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 8
• Total formula weight: 132977.96

Authors

Mohammed, F.,Stones, D.H.,Willcox, B.E. (deposition date: 2017-11-06, release date: 2018-11-07, Last modification date: 2024-01-17)

Primary citation

Mohammed, F.,Stones, D.H.,Willcox, B.E.
Application of the immunoregulatory receptor LILRB1 as a crystallisation chaperone for human class I MHC complexes.
J. Immunol. Methods, 464:47-56, 2019

PubMed Abstract: X-ray crystallographic studies of class I peptide-MHC molecules (pMHC) continue to provide important insights into immune recognition, however their success depends on generation of diffraction-quality crystals, which remains a significant challenge. While protein engineering techniques such as surface-entropy reduction and lysine methylation have proven utility in facilitating and/or improving protein crystallisation, they risk affecting the conformation and biochemistry of the class I MHC antigen binding groove. An attractive alternative is the use of noncovalent crystallisation chaperones, however these have not been developed for pMHC. Here we describe a method for promoting class I pMHC crystallisation, by exploiting its natural ligand interaction with the immunoregulatory receptor LILRB1 as a novel crystallisation chaperone. First, focussing on a model HIV-1-derived HLA-A2-restricted peptide, we determined a 2.4 Å HLA-A2/LILRB1 structure, which validated that co-crystallisation with LILRB1 does not alter conformation of the antigenic peptide. We then demonstrated that addition of LILRB1 enhanced the crystallisation of multiple peptide-HLA-A2 complexes, and identified a generic condition for initial co-crystallisation. LILRB1 chaperone-based crystallisation enabled structure determination for HLA-A2 complexes previously intransigent to crystallisation, including both conventional and post-translationally-modified peptides, of diverse lengths. Since both the LILRB1 recognition interface on the HLA-A2 α3 domain molecule and HLA-A2-mediated crystal contacts are predominantly conserved across class I MHC molecules, the approach we outline could prove applicable to a diverse range of class I pMHC. LILRB1 chaperone-mediated crystallisation should expedite molecular insights into the immunobiology of diverse immune-related diseases and immunotherapeutic strategies, particularly involving class I pMHC complexes that are challenging to crystallise.

PubMed: 30365927
DOI: 10.1016/j.jim.2018.10.011

Experimental method

X-RAY DIFFRACTION (2.3 Å)