Investigation into the basis of protein-lipid interactions for ATP-Binding Cassette (ABC) transporters BmrA and P-gp, using novel polymer-based solubi

Membrane proteins (MPs) are a group of biomolecules that function as transporters to move substrates across a cell membrane. One of the most widespread families of MPs are ATP-Binding Cassette (ABC) transporters. Two homologous members of the ABC transporter superfamily -Bacillus subtilis multidrug resistance ABC transporter (BmrA) and P-glycoprotein (P-gp)- are known to transport a wide variety of substrates including chemo-active drugs such as doxorubicin. Overexpression of these MPs has been linked to chemotherapeutic failure and multi-drug resistance, making structural and functional characterisation critical for drug development.
Unfortunately, the study of MPs is challenging due to their hydrophobicity. Traditionally, detergents were utilised to remove MPs from a membrane before packaging into discrete micelles. However, this method raises concerns as the disruption of protein-lipid interactions has been shown to influence protein structure and function. Alternative methods involving synthetic polymers such as Styrene Maleic Acid (SMA) and Diisobutylene-Maleic Acid (DIBMA) have therefore become popular. They self-insert into the membrane, isolating segments of lipids with MPs embedded - known as SMA Lipid Particles (SMALPs) or DIBMA Lipid Particles (DIBMALPs).
This study aims to utilise polymer-based solubilisation to investigate the basis of protein-lipid interactions for ABC transporters. This will be accomplished by assessing protein structure and function in proteo-liposomes of varying lipid compositions. We also aim to identify the optimal polymers for ABC transporter solubilisation to streamline protein production and support polymer-based methodology.