Dynamics of free versus complexed β2-microglobulin and the evolution of interfaces in MHC class I molecules
In major histocompatibility complex (MHC) class I molecules, monomorphic β2-microglobulin (β2m) is non-covalently bound to a heavy chain (HC) exhibiting a variable degree of polymorphism. β2M can stabilize a wide variety of complexes ranging from classical peptide binding to nonclassical lipid presenting MHC class I molecules as well as to MHC class I-like molecules that do not bind small ligands. Here we aim to assess the dynamics of individual regions in free as well as complexed β2m and to understand the evolution of the interfaces between β2m and different HC. Using human β2m and the HLA–B*27:09 complex as a model system, a comparison of free and HC-bound β2m by nuclear magnetic resonance spectroscopy was initially carried out. Although some regions retain their flexibility also after complex formation, these studies reveal that most parts of β2m gain rigidity upon binding to the HC. Sequence analyses demonstrate that some of the residues exhibiting flexibility participate in evolutionarily conserved β2m–HC contacts which are detectable in diverse vertebrate species or characterize a particular group of MHC class I complexes such as peptide- or lipid-binding molecules. Therefore, the spectroscopic experiments and the interface analyses demonstrate that β2m fulfills its role of interacting with diverse MHC class I HC as well as effector cell receptors not only by engaging in conserved intermolecular contacts but also by falling back upon key interface residues that exhibit a high degree of flexibility.
Keywordsβ2m dynamics β2m–MHC class I heavy chain interface MHC class I and class I-like molecules MHC evolution NMR spectroscopy
We are grateful to Christina Schnick (Institut für Immungenetik, Charité-Universitätsmedizin Berlin), Annette Diehl and Natalja Erdmann (Leibniz-Institut für Molekulare Pharmakologie, Berlin) for excellent technical support. This work was supported by the Deutsche Forschungsgemeinschaft (grants Na226/12-3, UC8/1-2, UC8/2-1, SCHM880/9-1 and SFB 449/B6). A. Ziegler thanks the VolkswagenStiftung for financial assistance (grant I/79 989). B. Loll is grateful for support by the Forschungskommission of the Freie Universität Berlin and Fonds der Chemischen Industrie. C.-S. Hee thanks the Berliner Krebsgesellschaft (Ernst von Leyden Stipendium) and the Deutsche Forschungsgemeinschaft for support through UC8/2-1.
- Cavanagh J, Fairbrother JW, Palmer AG III, Skelton NJ (1996) Protein NMR spectroscopy principles and practice. Academic Press, San DiegoGoogle Scholar
- Chu F, Lou Z, Chen YW, Liu Y, Gao B, Zong L, Khan AH, Bell JI, Rao Z, Gao GF (2007) First glimpse of the peptide presentation by rhesus macaque MHC class I: crystal structures of Mamu-A*01 complexed with two immunogenic SIV epitopes and insights into CTL escape. J Immunol 178:944–952PubMedGoogle Scholar
- Delano WL (2002) The PyMOL Molecular Graphic System. San Carlos, CA, DeLano ScientificGoogle Scholar
- R Development Core Team (2010) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.r-project.org/
- Esposito G, Ricagno S, Corazza A, Rennella E, Gümral D, Mimmi MC, Betto E, Pucillo CE, Fogolari F, Viglino P, Raimondi S, Giorgetti S, Bolognesi B, Merlini G, Stoppini M, Bolognesi M, Bellotti V (2008) The controlling roles of Trp60 and Trp95 in beta2-microglobulin function, folding and amyloid aggregation properties. J Mol Biol 378:887–897PubMedCrossRefGoogle Scholar
- Kern PS, Teng MK, Smolyar A, Liu JH, Liu J, Hussey RE, Spoerl R, Chang HC, Reinherz EL, Wang JH (1998) Structural basis of CD8 coreceptor function revealed by crystallographic analysis of a murine CD8alphaalpha ectodomain fragment in complex with H-2Kb. Immunity 9:519–530PubMedCrossRefGoogle Scholar
- Koch M, Camp S, Collen T, Avila D, Salomonsen J, Wallny HJ, van Hateren A, Hunt L, Jacob JP, Johnston F, Marston DA, Shaw I, Dunbar PR, Cerundolo V, Jones EY, Kaufman J (2007) Structures of an MHC class I molecule from B21 chickens illustrate promiscuous peptide binding. Immunity 27:885–899PubMedCrossRefGoogle Scholar
- Okon M, Bray P, Vucelić D (1992) 1H NMR assignments and secondary structure of human beta 2-microglobulin in solution. Biochemistry 31:8906-8915.Google Scholar
- Pervushin K, Riek R, Wider G, Wüthrich K (1997) Attenuated T2 relaxation by mutual cancellation of dipole-dipole coupling and chemical shift anisotropy indicates an avenue to NMR structures of very large biological macromolecules in solution. Proc Natl Acad Sci USA 94:12366–12371PubMedCrossRefGoogle Scholar
- Shields MJ, Kubota R, Hodgson W, Jacobson S, Biddison WE, Ribaudo RK (1998) The effect of human beta2-microglobulin on major histocompatibility complex I peptide loading and the engineering of a high affinity variant. Implications for peptide-based vaccines. J Biol Chem 273:28010–28018PubMedCrossRefGoogle Scholar
- Shiroishi M, Kuroki K, Rasubala L, Tsumoto K, Kumagai I, Kurimoto E, Kato K, Kohda D, Maenaka K (2006) Structural basis for recognition of the nonclassical MHC molecule HLA-G by the leukocyte Ig-like receptor B2 (LILRB2/LIR2/ILT4/CD85d). Proc Natl Acad Sci USA 103:16412–16417PubMedCrossRefGoogle Scholar