6533b7d6fe1ef96bd1267034

RESEARCH PRODUCT

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

Mar OrzáezIsmael MingarroVicente Andreu-fernándezLuca MonticelliMaria Jesús García-murriaManuel Bañó-poloJuliette Martin

subject

0301 basic medicineProtein familyCèl·lulesBiologyBiochemistryMitochondrial Proteins03 medical and health sciencesProtein DomainsMembranes (Biologia)Protein-fragment complementation assayMembrane BiologyMicrosomesProto-Oncogene ProteinsHumansMolecular BiologyAdaptor Proteins Signal TransducingGeneticsBcl-2-Like Protein 11030102 biochemistry & molecular biologyCell MembraneBcl-2 familyProteïnes de membranaMembrane ProteinsBiological membraneCell BiologyFusion proteinTransmembrane proteinCell biology030104 developmental biologyMembraneProto-Oncogene Proteins c-bcl-2Membrane proteinB-cell lymphoma 2 (Bcl-2) family BH3-only apoptosis membrane insertion membrane protein mitochondrial apoptosis transmembrane domainApoptosis Regulatory ProteinsHydrophobic and Hydrophilic InteractionsHeLa Cells

description

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.

https://doi.org/10.1074/jbc.m116.733634