Structure-function mapping of interleukin 1 precursors. Cleavage leads to a conformational change in the mature protein.
The two interleukin 1 (IL-1) genes (IL-1 alpha and beta) encode 31-kDa precursor molecules, which are cleaved upon secretion to generate the mature, active, carboxyl-terminal 17-kDa proteins. The IL-1 beta precursor is inactive, whereas the IL-1 alpha precursor is as active as the mature IL-1 alpha. In this report, we demonstrate that when either of the recombinant precursors is processed to the mature form, the mature region undergoes a conformational change from a proteinase K-sensitive structure to one that is proteinase K-insensitive. In addition, cysteine residues that are exposed to solvent in the IL-1 beta precursor become buried in the mature protein. Limited structure-activity mapping of the IL-1 beta precursor indicates that the amino-terminal 76 residues are responsible for the conformational change, whereas the most dramatic change in biological activity occurs after further removal of residues 77-94. These findings suggest that the altered structure of the mature region in precursor IL-1s has been conserved for some function. Denaturation/renaturation experiments implicate the precursor domain in protein folding, and by analogy with signal-directed secretory proteins, the unique conformation of the precursors may play a role in IL-1 secretion.
Hazuda
D J
DJ
Department of Molecular Genetics, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406-0939.
Strickler
J
J
Simon
P
P
Young
P R
PR
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D010450:Endopeptidases; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D006801:Humans; D007375:Interleukin-1 / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011487:Protein Conformation; D011489:Protein Denaturation; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D013329:Structure-Activity Relationship
D007375:Interleukin-1; D010446:Peptide Fragments; D011498:Protein Precursors; D011994:Recombinant Proteins; C043830:interleukin 1 precursor; D010450:Endopeptidases