4TX5

Crystal structure of Smac-DIABLO (in space group P65)

Summary for 4TX5

• Entry DOI: 10.2210/pdb4tx5/pdb
• Descriptor: Diablo homolog, mitochondrial, (4S)-2-METHYL-2,4-PENTANEDIOL, ACETATE ION, ... (4 entities in total)
• Functional Keywords: smac-diablo, apoptosis
• Biological source: Homo sapiens (Human)
• Cellular location: Mitochondrion : Q9NR28
• Total number of polymer chains: 2
• Total formula weight: 44661.72

Authors

Milani, M.,Mastangelo, E.,Cossu, F. (deposition date: 2014-07-02, release date: 2015-07-15, Last modification date: 2023-12-20)

Primary citation

Mastrangelo, E.,Vachette, P.,Cossu, F.,Malvezzi, F.,Bolognesi, M.,Milani, M.
The activator of apoptosis Smac-DIABLO acts as a tetramer in solution.
Biophys.J., 108:714-723, 2015

PubMed Abstract: Smac-DIABLO in its mature form (20.8 kDa) binds to baculoviral IAP repeat (BIR) domains of inhibitor of apoptosis proteins (IAPs) releasing their inhibitory effects on caspases, thus promoting cell death. Despite its apparent molecular mass (∼100 kDa), Smac-DIABLO was held to be a dimer in solution, simultaneously targeting two distinct BIR domains. We report an extensive biophysical characterization of the protein alone and in complex with the X-linked IAP (XIAP)-BIR2-BIR3 domains. Our data show that Smac-DIABLO adopts a tetrameric assembly in solution and that the tetramer is able to bind two BIR2-BIR3 pairs of domains. Our small-angle x-ray scattering-based tetrameric model of Smac-DIABLO/BIR2-BIR3 highlights some conformational freedom of the complex that may be related to optimization of IAPs binding.

PubMed: 25650938
DOI: 10.1016/j.bpj.2014.11.3471

Experimental method

X-RAY DIFFRACTION (1.8 Å)