Sequential processing of human proIL-1β by caspase-1 and subsequent folding determined by a combined in vitro and in silico approach

P. W. Swaan, D. L. Knoell, F. Helsper, M. D. Wewers

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Purpose. Interleukin-1β is a multifunctional cytokine produced by activated monocytes and macrophages that requires caspase-1 (IL-1 converting enzyme/ICE) to process the 31kDa inactive precursor protein to the biologically active 17kDa peptide. This activation event involves ICE cleavage at Asp27 (site 1) and Asp116 (site 2). To address the sequential processing at ICE cut sites we combined in vitro analysis and molecular modeling to investigate the sequence of molecular events. Methods. Pulse chase labeling followed by immunoprecipitation of IL-1β in activated human monocyte lysates demonstrated sequential cutting by ICE at site 1 before site 2 in vitro. To corroborate these findings, we constructed a homology model of proIL-1β after the crystal structure of another ICE substrate, human α1-antitrypsin (23% sequence identity). Results. Comparative modeling revealed that site 1 on proIL-1β is accessible to ICE but site 2 is not. Molecular dynamics simulations following ICE cleavage at site 1 and removal of the 3kDa aminoterminal fragment, rendered site 2 accessible to ICE. Conclusions. The close agreement between the in vitro and modeled behavior of IL-1β support our contention that IL-1β may be structurally related to α1-antitrypsin and also predicts that proIL-1β requires sequential processing for activation. These findings may facilitate the development of novel pharmacological agents that control posttranslational proIL-1β modification, thereby preventing excessive production of this potent inflammatory cytokine.

Original languageEnglish (US)
Pages (from-to)1083-1090
Number of pages8
JournalPharmaceutical Research
Volume18
Issue number8
DOIs
StatePublished - 2001

Keywords

  • Comparative modeling
  • Cytokines
  • Inflammation
  • Molecular dynamics
  • Protein folding

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry
  • Pharmacology (medical)

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