Starts 16 Sep 2022 10:00
Ends 16 Sep 2022 11:00
Central European Time
QLS Seminar - Solubilisation of membrane proteins and lipids into functional bilayer nanodiscs by poly(diisobutylene-alt-maleic acid) and other polymers
ICTP
Common area, second floor, former SISSA building
Via Beirut, 2
Membrane proteins play abundant roles in cellular and transport functions, thus represent a significant class of drug targets. However, their extraction and in vitro investigations are challenging due to their very hydrophobic nature. Conventionally, the extraction is achieved with the aid of a surface-active compound known as detergent, but most detergents cause irreversible loss of structure and activity to membrane proteins. To solve these problems scaffold proteins or amphiphilic polymers such as styrene/maleic acid (SMA) copolymers were introduced as alternatives to detergent, but the lipid order was affected and there were precipitations in the presence of divalent cations. We show that an alternating diisobutylene/maleic acid (DIBMA) copolymer shows equal performance to SMA in solubilizing phospholipids, stabilizes an integral membrane enzyme in functional bilayer nanodiscs, and extracts proteins of various sizes directly from cellular membranes. Unlike aromatic SMA, aliphatic DIBMA has only a mild effect on lipid acyl-chain order, does not interfere with optical spectroscopy in the far-UV range, and does not precipitate in the presence of low millimolar concentrations of divalent cations. DIBMA was found to be highly charged and had effect on the electrostatic environment of the membrane proteins, hence the development of other polymers such of supho-DIBMA and Glyco-DIBMA.