The three-dimensional solution structure of recombinant human interleukin-4, a protein of 133 residues and 15.4 kilodaltons that plays a key role in the immune and inflammatory systems, has been solved by multidimensional heteronuclear magnetic resonance spectroscopy. The structure is dominated by a left-handed four-helix bundle with an unusual topology comprising two overhand connections. The linker elements between the helices are formed by either long loops, small helical turns, or short strands. The overall topology is remarkably similar to that of growth hormone and granulocyte-macrophage colony stimulating factor, despite the absence of any sequence homology, and substantial differences in the relative lengths of the helices, the length and nature of the various connecting elements, and the pattern of disulfide bridges. These three proteins, however, bind to cell surface receptors belonging to the same hematopoietic superfamily, which suggests that interleukin-4 may interact with its receptor in an analogous manner to that observed in the crystal structure of the growth hormone-extracellular receptor complex.
The high-resolution three-dimensional solution structure of recombinant human interleukin-4 (IL-4), a protein of 15 kDa which plays a key role in the regulation of B and T lymphocytes, has been determined using threeand four-dimensional heteronuclear N M R spectroscopy. The structure is based on a total of 2973 experimental N M R restraints, comprising 25 15 approximate interproton distance restraints, 102 distance restraints for 51 backbone hydrogen bonds, and 356 torsion angle restraints. A total of 30 structures was calculated by means of hybrid distance geometry-simulated annealing, and the atomic rms distribution about the mean coordinate positions for residues 8-129 is 0.44 f 0.03 A for the backbone atoms, 0.83 f 0.03 A for all atoms, and 0.51 f 0.04 A for all atoms excluding disordered side chains. The Nand C-terminal residues (1-7 and 130-133, respectively) appear to be disordered. The structure of IL-4 is dominated by a left-handed four-helix bundle with an unusual topology comprising two overhand connections. The linker elements between the helices are formed by either long loops, small helical turns, or short strands. The latter include a mini anti-parallel P-sheet. A best fit superposition of the N M R structure of IL-4 with the 2.25 A resolution crystal structure [Wlodawer, A., Pavlovsky, A., & Gutschina, A. (1992) FEBS Lett. 309, 59-64] yields a backbone atomic rms difference of 1.37 A which can be mainly attributed to tighter packing of the helices in the crystal structure. This is indicated by an approximately 20% reduction in the axial separation of three pairs of helices (CYA-CYC, CYA-CYD, and CYCCYD) in the crystal structure relative to the N M R structure and may reflect the greater flexibility of the molecule in solution which is reduced in the crystal due to intermolecular contacts. Comparison of the N M R structure of IL-4 with the X-ray structures of two other related proteins, granulocyte-macrophage colony stimulating factor [ Diedrichs, K., Boone, T., & Karplus, P. A. (1992) Science 254,1779-17821 and human growth hormone [de Vos, A. M., Ultsch, M., & Kossiakoff, A. A. (1992) Science 255, 306-3121, that bind to the same hematopoietic superfamily of cell surface receptors reveals a remarkably similar topological fold, despite the absence of any significant overall sequence identity, and substantial differences in the relative lengths of the helices, the lengths and the nature of the various connecting elements, and the pattern and number of disulfide bridges. Indeed, the Ca atom coordinates of 72 and 79 residues of IL-4 can be superimposed on the Ca coordinates of granulocyte-macrophage colony stimulating factor and human growth hormone with rms differences of 1.7 and 2.0 A, respectively. Interleukin-4 (IL-4)' is a member of the cytokine family of proteins and plays a key role in the immune and inflammatory systems [see Paul and Ohara (1987), Yokota etal. (1988),Finkelmanetal. (1990),Pau1(1991),andBoulay and Paul (1992) for reviews]. IL-4 regulates B-cell proliferation and differentiation, modulates the survival, proliferation, and differentiation of T-cells, acts as a growth factor on mast cells, regulates macrophage activation, and induces the expression of VCAM-1 on endothelial cells. IL-4 is a potent inducer of human cytotoxic CD8+ T-cells, an activity which has been shown to be responsible for establishing tumorspecific systemic immunity to an established renal cancer by 7 This work was supported by the AIDS Targeted Anti-Viral Program of the Office of the Director of the National Institutes of Health (to G.M.C. and A.M.G.). t The coordinates of the 30 final simulated annealing structures of IL-4, together with the coordinates of the restrained minimized mean structure, (SA)r, and the complete list of experimental NMR restraints have been deposited in the Brookhaven Protein Data Bank. The accession numbers are lITI for the coordinates and IITI-MR for the complete set of experimental NMR restraints. National Institutes of Health. 11 Immunex Corporation. injection of renal tumor cells genetically engineered to secrete large doses of IL-4 locally (Golumbek et al., 1991). The very potent antitumor activity of IL-4 at the primary tumor site is also associated with the elicitation of a localized inflammatory infiltrate, dominated by eosinophils (Tepper et al., 1989, 1992). Additionally, IL-4 induces the expression of class I and I1 MHC molecules and the IgE low-affinity receptor
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of the secondary structure and folding topology of human interleukin-4 using three-dimensional heteronuclear magnetic resonance spectroscopyDaniel S. Garrett, Robert Powers, Carl J. March, Eric A. Frieden, G. Marius Clore, and Angela M. GronenbornCite this: Biochemistry 1992, 31, 17, 4347–4353Publication Date (Print):May 15, 1992Publication History Published online1 May 2002Published inissue 15 May 1992https://doi.org/10.1021/bi00132a027RIGHTS & PERMISSIONSArticle Views52Altmetric-Citations20LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (848 KB) Get e-Alerts Get e-Alerts
