Binding properties of the C-terminal domain of VIAF.
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.
Bisson
William H
WH
The Burnham Institute for Medical Research, 10901 North Torrey Pines Rd, La Jolla, CA 92037, USA.
Zhang
Ziming
Z
Welsh
Kate
K
Huang
Jui-Wen
JW
Ryan
Jennifer
J
Reed
John C
JC
Pellecchia
Maurizio
M
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
D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D053148:Caspase 3; C498322:PDCL3 protein, human; D009419:Nerve Tissue Proteins