Identification of an interleukin-15alpha receptor-binding site on human interleukin-15.
To identify the epitopes in human interleukin-15 (IL-15) that are responsible for binding to the interleukin-15 receptor alpha chain, antibody and receptor mapping by peptide scanning and site-directed mutagenesis was used. By using peptide scanning, we identified four regions in IL-15. The first region ((85)CKECEELEEKN(95)) is located in the C-D loop and is recognized by a set of non-inhibitory antibodies. The second region ((102)SFVHIVQMFIN(112)) is located in helix D and is recognized by two antibodies that are inhibitory of IL-15 bio-activity but not of IL-15 binding to IL-15Ralpha. The two remaining regions react with a recombinant soluble form of the IL-15Ralpha; the first ((44)LLELQVISL(52), peptide 1) corresponds to a sequence located in the B-helix and the second ((64)ENLII(68), peptide 2) to a sequence located in helix C. The latter is also contained in the epitope recognized by an antibody (monoclonal antibody B-E29) that prevents IL-15 binding to IL-15Ralpha. By site-directed mutagenesis, we confirmed that residues present in peptide 1 (Leu-45, Glu-46, Val-49, Ser-51, and Leu-52) and peptide 2 (Leu-66 and Ile-67) are involved in the binding of IL-15 to IL-15Ralpha. Furthermore, the results presented indicate that residues in the second peptide (Glu-64, Asn-65, and Ile-68) participate in IL-2Rbeta recruitment. This finding could have implications for the dynamics of receptor assembly. These results also indicate that the modes of interaction of IL-15 and IL-2 with their respective alpha chains are not completely analogous. Finally, some of the IL-15 mutants generated in this study displayed agonist or antagonist properties and may be useful as therapeutic agents.
Bernard
Jérôme
J
Groupe de Recherche Cytokines et Récepteurs, Unité INSERM 601, Institut de Biologie, 9 Quai Moncousu, 44093 Nantes Cedex 01, France.
Harb
Catherine
C
Mortier
Erwan
E
Quéméner
Agnès
A
Meloen
Rob H
RH
Vermot-Desroches
Claudine
C
Wijdeness
John
J
van Dijken
Peter
P
Grötzinger
Joachim
J
Slootstra
Jerry W
JW
Plet
Ariane
A
Jacques
Yannick
Y
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001665:Binding Sites; D016466:CHO Cells; D002455:Cell Division; D002460:Cell Line; D006224:Cricetinae; D019992:Databases as Topic; D004305:Dose-Response Relationship, Drug; D000939:Epitopes / Q000737:chemistry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D019409:Interleukin-15 / Q000737:chemistry* / Q000378:metabolism; D007376:Interleukin-2 / Q000737:chemistry; D007377:Interleukin-3 / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2 / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D000911:Antibodies, Monoclonal; D000939:Epitopes; C508024:IL15RA protein, human; C508025:Il15ra protein, mouse; D019409:Interleukin-15; D007376:Interleukin-2; D007377:Interleukin-3; D008024:Ligands; D010455:Peptides; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor