Tracking peptide–membrane interactions: Insights from in situ coupled confocal-atomic force microscopy imaging of NAP-22 peptide insertion and assembly

• Published in: Journal of structural biology Vol. 155; no. 3; pp. 458 - 469
• Main Authors: Shaw, James E., Epand, Raquel F., Sinnathamby, Koneswaran, Li, Zaiguo, Bittman, Robert, Epand, Richard M., Yip, Christopher M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2006
• Subjects: Animals; Atomic force microscopy; Boron Compounds - metabolism; Brain Chemistry - immunology; Calmodulin-Binding Proteins - metabolism; Confocal fluorescence microscopy; Cytoskeletal Proteins - metabolism; Diagnostic Imaging - methods; Lipid Bilayers - metabolism; Membrane domains; Membranes - metabolism; Microscopy, Atomic Force - methods; Models, Biological; Nerve Tissue Proteins - metabolism; Peptide Fragments - metabolism; Peptide–membrane interactions; Phosphatidylcholines - metabolism; Phosphotransferases (Alcohol Group Acceptor) - immunology; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Protein Binding; Supported lipid bilayers; Swine; Atomic force microscopy; Confocal fluorescence microscopy; Peptide–membrane interactions; Membrane domains; Supported lipid bilayers
• ISSN: 1047-8477; 1095-8657
• DOI: 10.1016/j.jsb.2006.04.015

Elucidating the role that charged membrane proteins play in determining cell membrane structure and dynamics is an area of active study. We have applied in situ correlated atomic force and confocal microscopies to characterize the interaction of the NAP-22 peptide with model membranes prepared as supported planar bilayers containing both liquid-ordered and liquid-disordered domains. Our results demonstrated that the NAP-22 peptide interacts with membranes in a concentration-dependent manner, preferentially inserting into DOPC ( l d) domains. While at low peptide concentrations, the NAP-22 peptide formed aggregate-like structures within the l d domains, at high peptide concentrations, it appeared to sequester cholesterol into the l d domains and recruited phosphatidyl- myo-inositol 4,5-bisphosphate by inducing a blending effect that homogenizes the phase-segregated domains into one liquid-ordered domain. This study describes a possible mechanism by which the NAP-22 peptide can affect neuronal morphology.