Title

Transmembrane pore formation by the carboxyl terminus of Bax protein

Authors

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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