title: Inhibition of caspase-2 by a designed ankyrin repeat protein: specificity, structure, and inhibition mechanism.
abstract: 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.
authors.affiliation: Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schweizer
authors.forename: Heidi
authors.initials: H
authors.lastname: Roschitzki-Voser
authors.forename: Patrick
authors.initials: P
authors.lastname: Amstutz
authors.forename: Christophe
authors.initials: C
authors.lastname: Briand
authors.forename: Maya
authors.initials: M
authors.lastname: Gulotti-Georgieva
authors.forename: Eva
authors.initials: E
authors.lastname: Prenosil
authors.forename: H Kaspar
authors.initials: HK
authors.lastname: Binz
authors.forename: Guido
authors.initials: G
authors.lastname: Capitani
authors.forename: Antonio
authors.initials: A
authors.lastname: Baici
authors.forename: Andreas
authors.initials: A
authors.lastname: Plückthun
authors.forename: Markus G
authors.initials: MG
authors.lastname: Grütter
mesh_terms: 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
chemical_list: D061945:Caspase Inhibitors; C490360:CASP2 protein, human; D053143:Caspase 2; D003546:Cysteine Endopeptidases