Interleukin 6 is a 184-aa polypeptide postulated to belong to the class of helical cytokines. We built a three-dimensional model of human interleukin 6 based on the similarity of its hydrophobicity pattern with that of other cytokines and on the x-ray structure of growth hormone, interleukin 2, interleukin 4, interferon β, and granulocyte-macrophage colony-stimulating factor. The resulting model is a bundle of four α-helices and suggests possible alternative conformations for the 9 C-terminal amino acids; in this region, the importance of Arg-182 and Met-184 for biological activity has been demonstrated [Lutticken, C., Kruttgen, A., Moller, C., Heinrich, P. C. and Rose-John, S. (1991) FEBS Lett. 282, 265-267]. Therefore, we generated a large collection of single-amino acid variants in residues 175-181. Analysis of their biological activity in two systems and the receptor binding properties of a subset of the mutants indicates that the entire region is involved in forming the receptor binding surface and supports the hypothesis that this region does not assume an α-helical conformation. Remarkably, we also found a mutant with receptor affinity and biological activity much higher than wild type; the potential therapeutical value of this finding is discussed.
Saturation mutagenesis of the human interleukin 6 receptor-binding site: Implications for its three-dimensional structure / R., Savino; A., Lahm; M., Giorgio; A., Cabibbo; Tramontano, Anna; G., Ciliberto. - In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - ISSN 0027-8424. - 90:9(1993), pp. 4067-4071. [10.1073/pnas.90.9.4067]
Saturation mutagenesis of the human interleukin 6 receptor-binding site: Implications for its three-dimensional structure
TRAMONTANO, ANNA;
1993
Abstract
Interleukin 6 is a 184-aa polypeptide postulated to belong to the class of helical cytokines. We built a three-dimensional model of human interleukin 6 based on the similarity of its hydrophobicity pattern with that of other cytokines and on the x-ray structure of growth hormone, interleukin 2, interleukin 4, interferon β, and granulocyte-macrophage colony-stimulating factor. The resulting model is a bundle of four α-helices and suggests possible alternative conformations for the 9 C-terminal amino acids; in this region, the importance of Arg-182 and Met-184 for biological activity has been demonstrated [Lutticken, C., Kruttgen, A., Moller, C., Heinrich, P. C. and Rose-John, S. (1991) FEBS Lett. 282, 265-267]. Therefore, we generated a large collection of single-amino acid variants in residues 175-181. Analysis of their biological activity in two systems and the receptor binding properties of a subset of the mutants indicates that the entire region is involved in forming the receptor binding surface and supports the hypothesis that this region does not assume an α-helical conformation. Remarkably, we also found a mutant with receptor affinity and biological activity much higher than wild type; the potential therapeutical value of this finding is discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.