Open AccessDefinition of receptor binding sites on human interleukin‐11 by molecular modeling‐guided mutagenesis
Author(s) -
Tacken Ingrid,
Dahmen Heike,
Boisteau Olivier,
Minvielle Stéphane,
Jacques Yannick,
Grötzinger Joachim,
Küster Andrea,
Horsten Ursula,
Blanc Chrystel,
A. MonteroJulian Felix,
Heinrich Peter C.,
MüllerNewen Gerhard
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00755.x
Subject(s) - glycoprotein 130 , oncostatin m , ciliary neurotrophic factor , leukemia inhibitory factor receptor , biology , leukemia inhibitory factor , mutant , receptor , mutagenesis , microbiology and biotechnology , cytokine , interleukin 6 , biochemistry , genetics , neurotrophic factors , gene
Interleukin‐11 (IL‐11) belongs to the interleukin‐6 (IL‐6)‐type subfamily of long‐chain helical cytokines including IL‐6, ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), oncostatin M, and cardiotrophin‐1, which all share the glycoprotein gp130 as a signal transducing receptor component. IL‐11 acts on cells expressing gp130 and the IL‐11 receptor (IL‐11R) α‐subunit (IL‐11Rα). The structural epitopes of IL‐11 required for the recruitment of the individual receptor subunits have not yet been defined. Based on the structure of CNTF, a three‐dimensional model of human IL‐11 was built. Using this model, 10 surface exposed amino acid residues of IL‐11 were selected for mutagenesis using analogies to the well‐characterized receptor recruitment sites of IL‐6, CNTF, and LIF. The respective mutants of human IL‐11 were expressed as soluble fusion proteins in bacteria. Their biological activities were determined on HepG2 and Ba/F3‐130‐11α cells. Several mutants with substantially decreased bioactivity and one hyperagonistic mutant were identified and further analyzed with regard to recruitment of IL‐11Rα and gp130. The low‐activity mutant I171D still binds IL‐11Rα but fails to recruit gp130, whereas the hyperagonistic variant R135E more efficiently engages the IL‐11R subunits. The low‐activity mutants R190E and L194D failed to bind to IL‐11Rα. These findings reveal a common mechanism of receptor recruitment in the family of IL‐6‐type cytokines and offer considerable perspectives for the rational design of IL‐11 antagonists and hyperagonists.