National Center for
1R2D: Structure Of Human Bcl-xl At 1.95 Angstroms
J. Biol. Chem. (2004) 279 p.2159-2165
Cells expressing high levels of the BCL-X(L) anti-apoptotic protein are preferentially killed by the mitochondrial inhibitor antimycin A (AA). Computational modeling predicts a binding site for AA in the extended hydrophobic groove on BCL-X(L), previously identified as an interface for dimerization to BAX and related proapoptotic proteins. Here, we identify BCL-X(L) hydrophobic groove mutants with normal cellular anti-apoptotic function but suppressed sensitivity to AA. The LD(50) of AA for cells expressing BCL-X(L) mutants directly correlates with the measured in vitro dissociation constants for AA binding. These results indicate that BCL-X(L) is a principal target mediating AA cytotoxicity.