Transmembrane pore formation by the carboxyl terminus of Bax protein

    Authors

    P. Garg; K. N. Nemec; A. R. Khaled;S. A. Tatulian

    Comments

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    Abbreviated Journal Title

    Biochim. Biophys. Acta-Biomembr.

    Keywords

    Peptide; Membrane pore; Kinetics; Calcein release; Oligomeric state; OUTER MITOCHONDRIAL-MEMBRANE; CELL-DEATH; CYTOCHROME-C; PROAPOPTOTIC; BAX; BCL-2 FAMILY; PEPTIDE GALA; PERMEABILIZATION; LIPOSOMES; BINDING; APOPTOSIS; Biochemistry & Molecular Biology; Biophysics

    Abstract

    Bax is a cytosolic protein that responds to various apoptotic signals by binding to the outer mitochondrial membrane, resulting in membrane permeabilization, release of cytochrome c, and caspase-mediated cell death. Currently discussed mechanisms of membrane perforation include formation of hetero-oligomeric complexes of Bax with other pro-apoptotic proteins such as Bak, or membrane insertion of multiple hydrophobic helices of Bax, or formation of lipidic pores physically aided by mitochondrial membrane-inserted proteins. There is compelling evidence provided by our and other groups indicating that the C-terminal "helix 9" of Bax mediates membrane binding and pore formation, yet the mechanism of pore forming capability of Bax C-terminus remains unclear. Here we show that a 20-amino acid peptide corresponding to Box C-terminus (VTIFVAGVLTASLTIWKKMG) and two mutants where the two lysines are replaced with glutamate or leucine have potent membrane pore forming activities in zwitterionic and anionic phospholipid membranes. Analysis of the kinetics of calcein release from lipid vesicles allows determination of rate constants of pore formation, peptide peptide affinities within the membrane, the oligomeric state of transmembrane pores, and the importance of the lysine residues. These data provide insight into the molecular details of membrane pore formation by a Bax-derived peptide and open new opportunities for design of peptide-based cytotoxic agents. (C) 2012 Elsevier B.V. All rights reserved.

    Journal Title

    Biochimica Et Biophysica Acta-Biomembranes

    Volume

    1828

    Issue/Number

    2

    Publication Date

    1-1-2013

    Document Type

    Article

    Language

    English

    First Page

    732

    Last Page

    742

    WOS Identifier

    WOS:000315004600063

    ISSN

    0005-2736

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