TY - JOUR
T1 - Lipid-induced conformation of helix 7 from the pore-forming domain of the Bacillus thuringiensis Cry4Ba toxin
T2 - Implications for toxicity mechanism
AU - Tiewsiri, Kasorn
AU - Fischer, Wolfgang B.
AU - Angsuthanasombat, Chanan
N1 - Funding Information:
We are grateful to Dr. Jaume Torres (School of Biological Sciences, Nanyang Technological University, Singapore) for making available facilities in ATR-FTIR studies and critical comments. Support for this work has been generously funded by the Thailand Research Fund (TRF) in cooperation with the Commission of Higher Education (to C.A.). The Royal Golden Jubilee Ph.D. scholarship from TRF (to K.T.) is gratefully acknowledged.
PY - 2009/2
Y1 - 2009/2
N2 - Helix 7 in the Cry4Ba-pore-forming domain contains conserved Tyr249 and Phe264 that are crucially involved in mosquito-larvicidal activity. We have now characterized lipid-induced conformation of a 27-residue Cry4Ba-α7 peptide in phospholipid membranes using ATR-FTIR and hydrogen/deuterium (H+/D+) exchange experiments. ATR-FTIR results showed that conformation of this peptide is influenced by lipid composition and peptide-lipid ratio. For zwitterionic membranes, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1,2-didecanoyl-sn-glycero-3-phosphocholine, the peptide adopted both α-helix and α-structure, but only α-helical conformation was observed in anionic membranes (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol). H+/D+ exchange results showed protection of ∼90% in DMPC for β-form, while α-helical form was found preferentially on membrane surface with both critical aromatic residues pointing towards bilayers. Analysis of 10-ns simulations of Cry4Ba-α7 in DMPC supports the stability of α-helical and β-conformations for membrane-associated and membrane-inserted states, respectively. We suggest that this lipid-induced conformational change of α7 is conceivably related to pore-forming mechanism as structural requirement for efficient membrane insertion.
AB - Helix 7 in the Cry4Ba-pore-forming domain contains conserved Tyr249 and Phe264 that are crucially involved in mosquito-larvicidal activity. We have now characterized lipid-induced conformation of a 27-residue Cry4Ba-α7 peptide in phospholipid membranes using ATR-FTIR and hydrogen/deuterium (H+/D+) exchange experiments. ATR-FTIR results showed that conformation of this peptide is influenced by lipid composition and peptide-lipid ratio. For zwitterionic membranes, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1,2-didecanoyl-sn-glycero-3-phosphocholine, the peptide adopted both α-helix and α-structure, but only α-helical conformation was observed in anionic membranes (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol). H+/D+ exchange results showed protection of ∼90% in DMPC for β-form, while α-helical form was found preferentially on membrane surface with both critical aromatic residues pointing towards bilayers. Analysis of 10-ns simulations of Cry4Ba-α7 in DMPC supports the stability of α-helical and β-conformations for membrane-associated and membrane-inserted states, respectively. We suggest that this lipid-induced conformational change of α7 is conceivably related to pore-forming mechanism as structural requirement for efficient membrane insertion.
KW - ATR-FTIR
KW - Conserved aromatic residue
KW - Cry δ-endotoxin
KW - H/D exchange
KW - MD simulations
KW - Zwitterionic membranes
UR - http://www.scopus.com/inward/record.url?scp=58849125465&partnerID=8YFLogxK
U2 - 10.1016/j.abb.2008.11.025
DO - 10.1016/j.abb.2008.11.025
M3 - Article
C2 - 19103150
AN - SCOPUS:58849125465
SN - 0003-9861
VL - 482
SP - 17
EP - 24
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1-2
ER -