title: Addition of a small hydrophobic segment from the head region to an amphipathic leucine zipper like motif of E. coli toxin hemolysin E enhances the peptide-induced permeability of zwitterionic lipid vesicles.
abstract: To find out the sequence requirement of the H-205 peptide, containing an amphipathic leucine zipper motif corresponding to the amino acid (a.a.) region 205-234 of hemolysin E (HlyE) to induce efficient permeation in zwitterionic lipid vesicles, the peptide was extended at the N-terminal after the addition of seven amino acids from the predicted transmembrane region in the head domain of the protein-toxin. The new peptide, H-198 (a.a. 198-234) and a scrambled mutant peptide of the same size were synthesized, fluorescently labeled and characterized functionally and structurally. The results showed that H-198 induced significantly higher permeation in the zwitterionic PC/Chol lipid vesicles than its shorter version, H-205. H-198 formed large aggregates in the PC/Chol vesicles unlike H-205 and also adopted more helical structure in the membrane mimetic environments compared to that of H-205. Fluorescence energy transfer experiments by flow cytometry indicated that only H-198 but not its mutant or H-205 oligomerized in the zwitterionic lipid vesicles, while in the negatively charged lipid vesicles both H-198 and H-205 formed oligomeric assembly. The results suggest a probable role of the hydrophobic residues of the head domain of HlyE in inducing permeability in the zwitterionic lipid vesicles by the peptide derived from the a.a. 198-234 of the toxin.
authors.affiliation: Molecular and Structural Biology Division, Central Drug Research Institute, Lucknow-226001, India.
authors.forename: Sharada Prasad
authors.initials: SP
authors.lastname: Yadav
authors.forename: Aqeel
authors.initials: A
authors.lastname: Ahmad
authors.forename: Jimut Kanti
authors.initials: JK
authors.lastname: Ghosh
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism; D016350:Leucine Zippers / Q000235:genetics*; D008969:Molecular Sequence Data; D010539:Permeability; D011487:Protein Conformation; D015202:Protein Engineering; D022161:Transport Vesicles / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C119944:hlyE protein, E coli