Insertion of a structural domain of interleukin (IL)-1 beta confers agonist activity to the IL-1 receptor antagonist. Implications for IL-1 bioactivity.
We showed previously that replacement of Lys-145 in the IL-1 receptor antagonist (IL-1ra) with Asp resulted in an analog (IL-1ra K145D) with partial agonist activity. To identify additional amino acids that affect IL-1 bioactivity, we created second site mutations in IL-1ra K145D. Substitutions of single amino acids surrounding position 145 were made; none of these substitutions increased the bioactivity of IL-1ra K145D. However, the insertion of the beta-bulge (QGEESN) of IL-1 beta at the corresponding region of IL-1ra K145D resulted in a 3-4-fold augmentation of bioactivity. An additional increase in agonist activity was observed when the beta-bulge was co-expressed with a second substitution (His-54 --> Pro) in IL-1ra K145D. We also show that the bioactivity of both IL-1ra K145D and the triple mutant IL-1ra K145D/H54P/QGEESN is dependent on interaction with the newly cloned IL-1 receptor accessory protein.
Greenfeder
S A
SA
Department of Inflammation/Autoimmune Diseases, Hoffman-La Roche Inc., Nutley, New Jersey 07110, USA.
Varnell
T
T
Powers
G
G
Lombard-Gillooly
K
K
Shuster
D
D
McIntyre
K W
KW
Ryan
D E
DE
Levin
W
W
Madison
V
V
Ju
G
G
D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000737:chemistry* / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012795:Sialoglycoproteins / Q000737:chemistry* / Q000494:pharmacology; D013329:Structure-Activity Relationship
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D017472:Receptors, Interleukin-1; D012795:Sialoglycoproteins