The structure and organization within the membrane of the helices composing the pore-forming domain of Bacillus thuringiensis δ-endotoxin are consistent with an "umbrella-like" structure of the pore

Ehud Gazit, Paolo La Rocca, Mark S.P. Sansom, Yechiel Shai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

164 Scopus citations

Abstract

The aim of this study was to elucidate the mechanism of membrane insertion and the structural organization of pores formed by Bacillus thuringiensis δ-endotoxin. We determined the relative affinities for membranes of peptides corresponding to the seven helices that compose the toxin pore-forming domain, their modes of membrane interaction, their structures within membranes, and their orientations relative to the membrane normal. In addition, we used resonance energy transfer measurements of all possible combinatorial pairs of membrane-bound helices to map the network of interactions between helices in their membrane-bound state. The interaction of the helices with the bilayer membrane was also probed by a Monte Carlo simulation protocol to determine lowest-energy orientations. Our results are consistent with a situation in which helices α4 and α5 insert into the membrane as a helical hairpin in an antiparallel manner, while the other helices lie on the membrane surface like the ribs of an umbrella (the "umbrella model"). Our results also support the suggestion that α7 may serve as a binding sensor to initiate the structural rearrangement of the pore-forming domain.

Original languageEnglish
Pages (from-to)12289-12294
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume95
Issue number21
DOIs
StatePublished - 13 Oct 1998
Externally publishedYes

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