Poster abstracts

Poster number 12 submitted by Miao Xiao

Crystallization of Cry δ-Endotoxins in Bicelles

Miao Xiao (Biophysics program, The Ohio State University)

Abstract:
The Cry delta-endotoxins from Bacillus thuringiensis (Bt) are toxic to Lepidoptera (butterflies, moths), and Diptera (Mosquitoes, flies), which are crop pests, or vectors of important human tropical diseases. It is widely accepted that the action of Bt toxins is to lyse midgut epithelial cells in the target insect by insertion into the plasma membrane to create ion channels or pores. With the objective of gaining a better understanding of mode of action and a better utilization of Cry toxins in pest control and disease vector control, we use bicelle as a general strategy to determine the structures of membrane inserted Cry protein. Five different Cry proteins, Cry1Aa, Cry1Ab, Cry1Ac, Cry4Aa and Cry19Aa have been purified and crystallized in bicelle. Crystals of Cry1Ab grown from bicelles have been obtained and the structure has been determined at a resolution of 3.5 Å in one plane. Protease K protection assay has shown that Cry1Ab protein inserts into DMPC/Chapso bicelles. The availability of the Cry delta-endotoxins structure in bicelle would guide further investigations to the molecular basis of the membrane insertion of Cry endotoxins.

References:
Schnepf E, Crickmore N, Van Rie J, Lereclus D, Baum J, Feitelson J, Zeigler DR, Dean DH. (1998) Bacillus thuringiensis and its pesticidal crystal proteins.
Microbiol Mol Biol Rev. 62(3):775-806.

Salem Faham & James U. Bowie(2002) Bicelle Crystallization: A New Method for Crystallizing Membrane Proteins Yields a Monomeric Bacteriorhodopsin Structure. J. Mol. Biol. 316, 1±6

Keywords: bicelle, cry protein