Interaction dynamics of lipid assemblies with biomolecules

• Main Author: Tae, Hyunhyuk
• Other Authors: Cho Nam-Joon
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Model lipid membrane; Biomolecules; Lipid-based mRNA delivery; Membrane biophysics
• Online Access: https://hdl.handle.net/10356/181323
• Institution: Nanyang Technological University

Plasma membranes are fundamentally structured by lipid bilayers as a basic framework along with various biological components, serving not only as barriers between the internal and external environments of cells and membrane-enclosed organelles but also as dynamic interfaces facilitating interactions with neighboring cells and the surrounding biomolecules. Therefore, investigating the interactions between lipid assemblies and biomolecules is essential for understanding fundamental biological processes, such as cellular signaling and transport, and for advancing membrane-targeting pharmaceuticals and lipid-based delivery systems. However, the intricate nature of biological membranes poses significant challenges for studying interactions with bioactive molecules in physiological settings. To overcome these obstacles, model lipid assembly platforms have been devised to create a controlled and adaptable environment of natural lipid membranes, facilitating the detailed examination of biomolecular interactions with precision. Herein, the interaction dynamics of model lipid assemblies with sucrose, membrane-associated peptides, and mRNA were reported. The overall hypothesis is that the integrated approach utilizing various model lipid assembly platforms can produce distinct observations that elucidate the dynamics of biomolecular interactions with lipid membranes. Based on this hypothesis, integrative methodologies across various model lipid assembly platforms were employed focusing on three biomolecules, which are sucrose, the membrane-associated C-terminal tail of the mitotic kinesin-like protein 2 (CTM peptides), and mRNA, intending to establish a comprehensive analytical framework to engineer the model lipid membranes, to uncover fundamental biological functions on plasma membranes, and to obtain biophysical foundations for developing lipid-based mRNA delivery systems. Surface-sensitive analyses demonstrated that optimal amounts of sucrose could maintain lipid membrane fluidity on dehydration, developing a widely applicable air-stable model lipid membrane. In addition, systematic design strategies were applied for sequential mutations of CTM peptide and model lipid membranes incorporating various receptors, thereby identifying the selective recognition of CTM peptide by a specific phosphatidylinositol phosphate (PIP) receptor with underlying molecular mechanisms. Lastly, cationic lipid assemblies were fabricated with distinct features to elucidate the influence of the biophysical characteristics of cationic lipid assemblies on their interaction dynamics with mRNA. Utilizing multiple analytical approaches, the study underscored the significance of the initial structure of cationic liposomes in determining the final architecture of mRNA-lipoplexes, highlighting the necessity of understanding the structural aspects of lipid-based mRNA delivery systems. In summary, the findings in this thesis will enhance the knowledge about the design, investigation, and interpretation principles underlying model lipid assemblies, leading to the identification of various biomolecular interactions with lipid membranes to reveal the fundamental biological phenomena and advance the biological evaluation of lipid-based nucleic acid delivery systems.