Identification of the discontinuous binding site in human interleukin 1 beta for the type I interleukin 1 receptor.
Human interleukin 1 beta (IL-1 beta) exerts its diverse biological effects by binding to specific receptors on target cells. Two types of IL-1 receptor (IL-1R) have been identified: the type I IL-1R (p80) and the type II IL-1R (p68). Using site-specific mutagenesis, we have identified the binding site on IL-1 beta for the murine type I IL-1R. Analogs of the IL-1 beta protein containing defined amino acid substitutions were produced and tested for competitive binding to the two IL-1Rs. Substitutions of the amino acids at seven positions resulted in analogs that had greater than or equal to 100-fold reductions in competitive binding to the type I IL-1R, while maintaining substantial binding to the type II IL-1R. These seven amino acids (Arg-4, Leu-6, Phe-46, Ile-56, Lys-93, Lys-103, and Glu-105) are clustered in the IL-1 beta molecule, forming a discontinuous binding site. The side chains of all seven residues are exposed on the surface of IL-1 beta. The cumulative binding energies contributed by each of the residues predict a binding affinity that is consistent with the observed Kd of the wild-type protein for the type I IL-1R.
Labriola-Tompkins
E
E
Department of Molecular Genetics, Hoffmann-La Roche Inc., Nutley, NJ 07110.
Chandran
C
C
Kaffka
K L
KL
Biondi
D
D
Graves
B J
BJ
Hatada
M
M
Madison
V S
VS
Karas
J
J
Kilian
P L
PL
Ju
G
G
D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007375:Interleukin-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011971:Receptors, Immunologic / Q000378:metabolism*; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014961:X-Ray Diffraction
D007375:Interleukin-1; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins