The C-terminal Domains of Apoptotic BH3-only Proteins Mediate Their Insertion into Distinct Biological Membranes

Autores de CIPF

• 

  Maria Mar Orzáez Calatayud

  Autor

Participantes ajenos a CIPF

• Andreu-Fernandez, V
• Garcia-Murria, MJ
• Bano-Polo, M
• Martin, J
• Monticelli, L
• Mingarro, I

Grupos de Investigación

• Laboratorio de Terapias Dirigidas en Cáncer e Inflamación

  

  Jefe/a de Grupo

  Maria Mar Orzáez Calatayud

Abstract

Changes in the equilibrium of pro-and anti-apoptotic members of the B-cell lymphoma-2 (Bcl-2) protein family in the mitochondrial outer membrane (MOM) induce structural changes that commit cells to apoptosis. Bcl-2 homology-3 (BH3)-only proteins participate in this process by either activating pro-apoptotic effectors or inhibiting anti-apoptotic components and by promoting MOM permeabilization. The association of BH3-only proteins with MOMs is necessary for the activation and amplification of death signals; however, the nature of this association remains controversial, as these proteins lack a canonical transmembrane sequence. Here we used an in vitro expression system to study the insertion capacity of hydrophobic C-terminal regions of the BH3-only proteins Bik, Bim, Noxa, Bmf, and Puma into microsomal membranes. An Escherichia coli complementation assay was used to validate the results in a cellular context, and peptide insertions were modeled using molecular dynamics simulations. We also found that some of the C-terminal domains were sufficient to direct green fluorescent protein fusion proteins to specific membranes in human cells, but the domains did not activate apoptosis. Thus, the hydrophobic regions in the C termini of BH3-only members associated in distinct ways with various biological membranes, suggesting that a detailed investigation of the entire process of apoptosis should include studying the membranes as a setting for protein-protein and protein-membrane interactions.

Keywords

• B-cell lymphoma 2 (Bcl-2) family, BH3-only, apoptosis, membrane insertion, membrane protein, mitochondrial apoptosis, transmembrane domain