Structure Of Complexes Of Helix-5 From Bax With Lipid Membranes

Bax is a proapoptotic protein implicated in the release of cell-death activating factors from the mitochondrial intermembrane space. Although the structure of the membrane-bound forms of Bax is unknown, it has been proposed to form proteolipidic pores. Studies with synthetic lipid vesicles have shown that fragments encompassing helix-5 of Bax retain a membrane permeabilization ability that is similar to that of the full-length protein. Here we report on the structure of peptide-membrane complexes formed by a Bax helix-5 peptide and lipid bilayers. The relative orientation of the peptide and the lipids are determined using site-specific infrared spectroscopy, assisted by isotopic labeling of…