A common allosteric site and mechanism in caspases.

We present a common allosteric mechanism for control of inflammatory and apoptotic caspases. Highly specific thiol-containing inhibitors of the human inflammatory caspase-1 were identified by using disulfide trapping, a method for site-directed small-molecule discovery. These compounds became trapped by forming a disulfide bond with a cysteine residue in the cavity at the dimer interface approximately 15 A away from the active site. Mutational and structural analysis uncovered a linear circuit of functional residues that runs from one active site through the allosteric cavity and into the second active site. Kinetic analysis revealed robust positive cooperativity not seen in other endopeptidases. Recently, disulfide trapping identified a similar small-molecule site and allosteric transition in the apoptotic caspase-7 that shares only a 23% sequence identity with caspase-1. Together, these studies show a general small-molecule-binding site for functionally reversing the zymogen activation of caspases and suggest a common regulatory site for the allosteric control of inflammation and apoptosis.
AuthorsJustin M Scheer, Michael J Romanowski, James A Wells
JournalProceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 103 Issue 20 Pg. 7595-600 (May 16 2006) ISSN: 0027-8424 [Print] United States
PMID16682620 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
Chemical References
  • Caspase Inhibitors
  • Disulfides
  • Sulfhydryl Compounds
  • Caspases
  • Allosteric Regulation
  • Amino Acid Sequence
  • Apoptosis (physiology)
  • Binding Sites
  • Caspase Inhibitors
  • Caspases (chemistry, genetics, metabolism)
  • Crystallography, X-Ray
  • Disulfides (chemistry)
  • Humans
  • Inflammation (metabolism)
  • Models, Molecular
  • Molecular Sequence Data
  • Molecular Structure
  • Protein Conformation
  • Sequence Alignment
  • Sulfhydryl Compounds (chemistry)

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