title: Binding properties of the C-terminal domain of VIAF.
abstract: The protein X-linked inhibitor of apoptosis (XIAP) plays an important role in caspase inactivation and as a consequence in the inhibition of apoptosis. It is known that IAP antagonists are able to specifically bind XIAP and reactivate caspase activity stimulating apoptosis. The viral IAP-associated factor (VIAF) protein is a novel IAP-interacting factor able to modulate caspase activation during apoptosis. We show that the C-terminal domain of VIAF (c-VIAF) is not able in vitro to behave as a direct IAP antagonist. By [15N-1H] HSQC NMR studies we revealed that c-VIAF binds to the RING domain of XIAP and characterized the important residues involved in the binding. Through 1D 1H-NMR screening of 1000 compounds from an in-house collection, we found that compound BI-86-E10 is able to bind to c-VIAF in a region adjacent to that interacting with the RING domain of XIAP, as supported by homology modeling and computational docking studies. After an initial round of SAR, the compound analog BI-86-E6 was found to bind with a K(d) value of 16.5 microM. These initial compounds may serve as chemical probes for further functional studies, possibly aimed at validating c-VIAF as a novel target for antiviral drug development.
authors.affiliation: The Burnham Institute for Medical Research, 10901 North Torrey Pines Rd, La Jolla, CA 92037, USA.
authors.forename: William H
authors.initials: WH
authors.lastname: Bisson
authors.forename: Ziming
authors.initials: Z
authors.lastname: Zhang
authors.forename: Kate
authors.initials: K
authors.lastname: Welsh
authors.forename: Jui-Wen
authors.initials: JW
authors.lastname: Huang
authors.forename: Jennifer
authors.initials: J
authors.lastname: Ryan
authors.forename: John C
authors.initials: JC
authors.lastname: Reed
authors.forename: Maurizio
authors.initials: M
authors.lastname: Pellecchia
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D001665:Binding Sites; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry*; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003198:Computer Simulation; D000882:Haplorhini; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D017434:Protein Structure, Tertiary; D009419:Nerve Tissue Proteins
chemical_list: D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D053148:Caspase 3; C498322:PDCL3 protein, human; D009419:Nerve Tissue Proteins