Crystal structure of baculovirus P35: Role of a novel reactive site loop in apoptotic caspase inhibition

Andrew J Fisher, Wilfred Dela Cruz, Stephen J. Zoog, Christine L. Schneider, Paul D. Friesen

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

The aspartate-specific caspases are critical protease effecters of programmed cell death and consequently represent important targets for apoptotic intervention. Baculovirus P35 is a potent substrate inhibitor of metazoan caspases, a property that accounts for its unique effectiveness in preventing apoptosis in phylogenetically diverse organisms. Here we report the 2.2 Å resolution crystal structure of P35, the first structure of a protein inhibitor of the death caspases. The P35 monomer possesses a solvent-exposed Loop that projects from the protein's main P-sheet core and positions the requisite aspartate cleavage site at the loop's apex. Distortion or destabilization of this reactive site loop by site-directed mutagenesis converted P35 to an efficient substrate which, unlike wild-type P35, failed to interact stably with the target caspase or block protease activity. Thus, cleavage alone is insufficient for caspase inhibition. These data are consistent with a new model wherein the P35 reactive site loop participates in a unique multi-step mechanism in which the spatial orientation of the loop with respect to the P35 core determines post-cleavage association and stoichiometric caspases.

Original languageEnglish (US)
Pages (from-to)2031-2039
Number of pages9
JournalEMBO Journal
Volume18
Issue number8
StatePublished - Apr 15 1999

Fingerprint

Baculoviridae
Caspases
Catalytic Domain
Crystal structure
Caspase Inhibitors
Aspartic Acid
Peptide Hydrolases
Site-Directed Mutagenesis
Mutagenesis
Cell death
Substrates
Proteins
Cell Death
Apoptosis
Monomers

Keywords

  • Apoptosis
  • Baculovirus
  • Caspase inhibitor
  • Crystallography
  • P35

ASJC Scopus subject areas

  • Genetics
  • Cell Biology

Cite this

Fisher, A. J., Dela Cruz, W., Zoog, S. J., Schneider, C. L., & Friesen, P. D. (1999). Crystal structure of baculovirus P35: Role of a novel reactive site loop in apoptotic caspase inhibition. EMBO Journal, 18(8), 2031-2039.

Crystal structure of baculovirus P35 : Role of a novel reactive site loop in apoptotic caspase inhibition. / Fisher, Andrew J; Dela Cruz, Wilfred; Zoog, Stephen J.; Schneider, Christine L.; Friesen, Paul D.

In: EMBO Journal, Vol. 18, No. 8, 15.04.1999, p. 2031-2039.

Research output: Contribution to journalArticle

Fisher, AJ, Dela Cruz, W, Zoog, SJ, Schneider, CL & Friesen, PD 1999, 'Crystal structure of baculovirus P35: Role of a novel reactive site loop in apoptotic caspase inhibition', EMBO Journal, vol. 18, no. 8, pp. 2031-2039.
Fisher, Andrew J ; Dela Cruz, Wilfred ; Zoog, Stephen J. ; Schneider, Christine L. ; Friesen, Paul D. / Crystal structure of baculovirus P35 : Role of a novel reactive site loop in apoptotic caspase inhibition. In: EMBO Journal. 1999 ; Vol. 18, No. 8. pp. 2031-2039.
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