The three-dimensional high resolution structure of human interferon α-2a determined by heteronuclear NMR spectroscopy in solution (original) (raw)
Related papers
Protein Science, 2006
Type I interferons (IFNs) are a family of homologous helical cytokines that exhibit pleiotropic effects on a wide variety of cell types, including antiviral activity and antibacterial, antiprozoal, immunomodulatory, and cell growth regulatory functions. Consequently, IFNs are the human proteins most widely used in the treatment of several kinds of cancer, hepatitis C, and multiple sclerosis. All type I IFNs bind to a cell surface receptor consisting of two subunits, IFNAR1 and IFNAR2, associating upon binding of interferon. The structure of the extracellular domain of IFNAR2 (R2-EC) was solved recently. Here we study the complex and the binding interface of IFNα2 with R2-EC using multidimensional NMR techniques. NMR shows that IFNα2 does not undergo significant structural changes upon binding to its receptor, suggesting a lock-and-key mechanism for binding. Cross saturation experiments were used to determine the receptor binding site upon IFNα2. The NMR data and previously published mutagenesis data were used to derive a docking model of the complex with an RMSD of 1 Å, and its well-defined orientation between IFNα2 and R2-EC and the structural quality greatly improve upon previously suggested models. The relative ligand–receptor orientation is believed to be important for interferon signaling and possibly one of the parameters that distinguish the different IFN I subtypes. This structural information provides important insight into interferon signaling processes and may allow improvement in the development of therapeutically used IFNs and IFN-like molecules.
The crystal structure of human interferon β at 2.2-Å resolution
Proceedings of the National Academy of Sciences, 1997
Type I interferons (IFNs) are helical cytokines that have diverse biological activities despite the fact that they appear to interact with the same receptor system. To achieve a better understanding of the structural basis for the different activities of ␣ and  IFNs, we have determined the crystal structure of glycosylated human IFN- at 2.2-Å resolution by molecular replacement. The molecule adopts a fold similar to that of the previously determined structures of murine IFN- and human IFN-␣ 2b but displays several distinct structural features. Like human IFN-␣ 2b , human IFN- contains a zinc-binding site at the interface of the two molecules in the asymmetric unit, raising the question of functional relevance for IFN- dimers. However, unlike the human IFN-␣ 2b dimer, in which homologous surfaces form the interface, human IFN- dimerizes with contact surfaces from opposite sides of the molecule. The relevance of the structure to the effects of point mutations in IFN- at specific exposed residues is discussed. A potential role of ligand-ligand interactions in the conformational assembly of IFN receptor components is discussed.
Type I interferon structures: Possible scaffolds for the interferon-α receptor complex
Canadian Journal of Chemistry
The structures of several type I interferons (IFNs) are known. We review the structural information known for IFN alphas and compare them to other interferons and cytokines. We also review the structural information known or proposed for IFN-cell receptor complexes. However, the structure of the IFN -cell receptor -IFN receptor2 (IFNAR2) and IFN receptor1 (IFNAR1) complex has not yet been determined. This paper describes a structural model of human IFN-IFNAR2/IFNAR1 complex using human IFN-a 2b dimer as the ligand. Both the structures of recombinant human IFN-a 2b and IFN-b were determined by X-ray crystallography as zinc-mediated dimers. Our proposed model was generated using human IFN-a 2b dimer docked with IFNAR2/IFNAR1. We compare our model with the receptor complex models proposed for IFN-b and IFN-g to contrast similarities and differences. The mutual binding sites of human IFN-a 2b and IFNAR2/IFNAR1 complex are consistent with available mutagenesis studies.
Type I interferon structures: Possible scaffolds for the interferon-alpha receptor complex
Canadian Journal of Chemistry, 2002
The structures of several type I interferons (IFNs) are known. We review the structural information known for IFN alphas and compare them to other interferons and cytokines. We also review the structural information known or proposed for IFN-cell receptor complexes. However, the structure of the IFN -cell receptor -IFN receptor2 (IFNAR2) and IFN receptor1 (IFNAR1) complex has not yet been determined. This paper describes a structural model of human IFN-IFNAR2/IFNAR1 complex using human IFN-a 2b dimer as the ligand. Both the structures of recombinant human IFN-a 2b and IFN-b were determined by X-ray crystallography as zinc-mediated dimers. Our proposed model was generated using human IFN-a 2b dimer docked with IFNAR2/IFNAR1. We compare our model with the receptor complex models proposed for IFN-b and IFN-g to contrast similarities and differences. The mutual binding sites of human IFN-a 2b and IFNAR2/IFNAR1 complex are consistent with available mutagenesis studies.
A homology model of human interferon α-2
Proteins: Structure, Function, and Genetics, 1993
An atomic coordinate five a-helix three-dimensional model is presented for human interferon 01-2 (HuIFNa2). The HuIFNa2 structure was constructed from murine interferon p (MuIFNp) by homology modeling using the STEREO and IMPACT programs. The HuIFNor2 model is consistent with its known biochemical and biophysical properties including epitope mapping. Lysine residues predicted to be buried in the model were primarily unreactive with succinimidyl-7-amino-4methylcoumarin-3-acetic acid (AMCA-NHS), a lysine modification agent, as shown by mass spectrometric analysis of tryptic digests. N-terminal sequence analysis of polypeptides generated by limited digestion of HuIFNor2 with endoproteinase Lys-C demonstrated rapid cleavage at K31, which is consistent with the presence of this residue in a loop in the proposed H u I F N d model. Based on this model structure potential receptor binding sites are identified. o 1993 wiley-Liss, hc.
Human Interferon-Beta Crystal Structure
1998
Type I interferons (IFNs) are helical cytokines that have diverse biological activities despite the fact that they appear to interact with the same receptor system. To achieve a better understanding of the structural basis for the different activities of ␣ and  IFNs, we have determined the crystal structure of glycosylated human IFN- at 2.2-Å resolution by molecular replacement. The molecule adopts a fold similar to that of the previously determined structures of murine IFN- and human IFN-␣ 2b but displays several distinct structural features. Like human IFN-␣ 2b , human IFN- contains a zinc-binding site at the interface of the two molecules in the asymmetric unit, raising the question of functional relevance for IFN- dimers. However, unlike the human IFN-␣ 2b dimer, in which homologous surfaces form the interface, human IFN- dimerizes with contact surfaces from opposite sides of the molecule. The relevance of the structure to the effects of point mutations in IFN- at specific exposed residues is discussed. A potential role of ligand-ligand interactions in the conformational assembly of IFN receptor components is discussed.
A homology model of human interferon a-2
Proteins, 1993
An atomic coordinate five a-helix three-dimensional model is presented for human interferon 01-2 (HuIFNa2). The HuIFNa2 structure was constructed from murine interferon p (MuIFNp) by homology modeling using the STEREO and IMPACT programs. The HuIFNor2 model is consistent with its known biochemical and biophysical properties including epitope mapping. Lysine residues predicted to be buried in the model were primarily unreactive with succinimidyl-7-amino-4methylcoumarin-3-acetic acid (AMCA-NHS), a lysine modification agent, as shown by mass spectrometric analysis of tryptic digests. N-terminal sequence analysis of polypeptides generated by limited digestion of HuIFNor2 with endoproteinase Lys-C demonstrated rapid cleavage at K31, which is consistent with the presence of this residue in a loop in the proposed H u I F N d model. Based on this model structure potential receptor binding sites are identified. o 1993 wiley-Liss, hc.
Homology model of human interferon-α8 and its receptor complex
Protein Science, 2008
Human interferond (HuIFNa8), a type I interferon (IFN), is a cytokine belonging to the hematopoietic superfamily that includes human growth hormone (HGH). Recent data identified two human type I IFN receptor components. One component (p40) was purified from human urine by its ability to bind to immobilized type I IFN. A second receptor component (IFNAR), consisting of two cytokine receptor-like domains (D200 and D200'), was identified by expression cloning. Murine cells transfected with a gene encoding this protein were able to produce an antiviral response to human IFNa8. Both of these receptor proteins have been identified as members of the immunoglobulin superfamily of which H G H receptor is a member. The cytokine receptor-like structural motifs present in p40 and IFNAR were modeled based on the HGH receptor X-ray structure. Models of the complexes of HuIFNa8 with the receptor subunits were built by superpositioning the conserved C a backbone of the HuIFNa8 and receptor subunit models with HGH and its receptor complex. The HuIFNa8 model was constructed from the Ca coordinates of murine interferon-p crystal structure. Electrostatic potentials and hydrophobic interactions appear to favor the model of HuIFNa8 interacting with p40 at site 1 and the D200' domain of IFNAR at site 2 because there are regions of complementary electrostatic potential and hydrophobic interactions at both of the proposed binding interfaces. Some of the predicted receptor binding residues within HuIFNa8 correspond to functionally important residues determined previously for human IFNal, IFNa2, and IFNa4 subtypes by site-directed mutagenesis studies. The models predict regions of interaction between HuIFNa8 and each of the receptor proteins, and provide insights into interactions between other type I IFNs (IFN-a subtypes and IFN-p) and their respective receptor components.