Alanine-scanning mutagenesis of alpha-helix D segment of interleukin-13 reveals new functionally important residues of the cytokine.
Publication/Presentation Date
11-8-2002
Abstract
We documented that alpha-helices A, C, and D in human interleukin-13 (IL13) participate in interaction with its respective receptors. We hypothesized that alpha-helix D is the site II of the cytokine that binds IL13Ralpha1, a component of the normal tissue heterodimeric signaling IL13/4 receptor (IL13/4R), and that alpha-helix D independently binds a monomeric IL13Ralpha2 receptor, which is a non-signaling glioma-restricted receptor for IL13. Therefore, we alanine-scanned mutagenized helix D of IL13 to identify the residues involved in the respective receptors interaction. Recombinant muteins of IL13 were produced in Escherichia coli, and their structural integrity and identity were verified. The alanine mutants were tested in functional cellular assays, in which IL13 interaction with IL13Ralpha2 (glioma cells) or an ability to functionally stimulate IL13/4R (TF-1 cells) were examined, and also in binding assays. We found that residues 105, 106, and 109 of the d-helix of IL13 are responsible for interacting with the glioma-associated receptor. Moreover, glutamic acids at positions 92 and 110, and leucine at position 104 was found to be important for IL13/4R stimulation. Thus, alpha-helix D of IL13 is the primary site responsible for interaction with the IL13 binding proteins. We propose a model that illustrates the binding mode of IL13 with cancer-related IL13Ralpha2 and physiological IL13/4R.
Volume
277
Issue
45
First Page
43194
Last Page
43205
ISSN
0021-9258
Published In/Presented At
Madhankumar, A. B., Mintz, A., & Debinski, W. (2002). Alanine-scanning mutagenesis of alpha-helix D segment of interleukin-13 reveals new functionally important residues of the cytokine. The Journal of biological chemistry, 277(45), 43194–43205. https://doi.org/10.1074/jbc.M205047200
Disciplines
Medicine and Health Sciences
PubMedID
12189139
Department(s)
Fellows and Residents
Document Type
Article