Primary Citation of Related Structures: 2I3H, 2I3I
PubMed Abstract:
Designed second mitochondrial activator of caspases (Smac) mimetics based on an accessible [7,5]-bicyclic scaffold bind to and antagonize protein interactions involving the inhibitor of apoptosis (IAP) proteins, X-chromosome-linked IAP (XIAP), melanoma IAP (ML-IAP), and c-IAPs 1 and 2 (cIAP1 and cIAP2) ...
Designed second mitochondrial activator of caspases (Smac) mimetics based on an accessible [7,5]-bicyclic scaffold bind to and antagonize protein interactions involving the inhibitor of apoptosis (IAP) proteins, X-chromosome-linked IAP (XIAP), melanoma IAP (ML-IAP), and c-IAPs 1 and 2 (cIAP1 and cIAP2). The design rationale is based on a combination of phage-panning data, peptide binding studies, and a survey of potential isosteres. The synthesis of two scaffolds is described. These compounds bind the XIAP-baculoviral IAP repeat 3 (BIR3), cIAP1-BIR3, cIAP2-BIR3, and ML-IAP-BIR domains with submicromolar affinities. The most potent Smac mimetic binds the cIAP1-BIR3 and ML-IAP-BIR domains with a K i of 50 nM. The X-ray crystal structure of this compound bound to an ML-IAP/XIAP chimeric BIR domain protein is compared with that of a complex with a phage-derived tetrapeptide, AVPW. The structures show that these compounds bind to the Smac-binding site on ML-IAP with identical hydrogen-bonding patterns and similar hydrophobic interactions. Consistent with the structural data, coimmunoprecipitation experiments demonstrate that the compounds can effectively block Smac interactions with ML-IAP. The compounds are further demonstrated to activate caspase-3 and -7, to reduce cell viability in assays using MDA-MB-231 breast cancer cells and A2058 melanoma cells, and to enhance doxorubicin-induced apoptosis in MDA-MB-231 cells.
Related Citations:
Engineering ML-IAP to produce an extraordinarily potent caspase-9 inhibitor: implications for Smac-dependent anti-apoptotic activity of ML-IAP Vucic, D., Franklin, M.C., Wallweber, H.J., Das, K., Eckelman, B.P., Shin, H., Elliott, L.O., Deshayes, K., Salvesen, G.S., Fairbrother, W.J. (2005) Biochem J 385: 11
Structure and Function Analysis of Peptide Antagonists of Melanoma Inhibitor of Apoptosis (ML-IAP) Franklin, M.C., Kadkhodayan, S., Ackerly, H., Alexandru, D., Distefano, M.D., Elliott, L.O., Flygare, J.A., Vucic, D., Deshayes, K., Fairbrother, W.J. (2003) Biochemistry 42: 8223
Organizational Affiliation:
Department of Protein Engineering, Genentech, Inc., South San Francisco, California 94080, USA.
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