Inhibition of caspase-2 by a designed ankyrin repeat protein: specificity, structure, and inhibition mechanism.
Specific and potent caspase inhibitors are indispensable for the dissection of the intricate pathways leading to apoptosis. We selected a designed ankyrin repeat protein (DARPin) from a combinatorial library that inhibits caspase-2 in vitro with a subnanomolar inhibition constant and, in contrast to the peptidic caspase inhibitors, with very high specificity for this particular caspase. The crystal structure of this inhibitor (AR_F8) in complex with caspase-2 reveals the molecular basis for the specificity and, together with kinetic analyses, the allosteric mechanism of inhibition. The structure also shows a conformation of the active site that can be exploited for the design of inhibitory compounds. AR_F8 is a specific inhibitor of an initiator caspase and has the potential to help identify the function of caspase-2 in the complex biological apoptotic signaling network.
Schweizer
Andreas
A
Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
Roschitzki-Voser
Heidi
H
Amstutz
Patrick
P
Briand
Christophe
C
Gulotti-Georgieva
Maya
M
Prenosil
Eva
E
Binz
H Kaspar
HK
Capitani
Guido
G
Baici
Antonio
A
Plückthun
Andreas
A
Grütter
Markus G
MG
D000595:Amino Acid Sequence; D017089:Ankyrin Repeat / Q000502:physiology*; D053143:Caspase 2 / Q000737:chemistry*; D061945:Caspase Inhibitors; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D015202:Protein Engineering
D061945:Caspase Inhibitors; C490360:CASP2 protein, human; D053143:Caspase 2; D003546:Cysteine Endopeptidases