COMPUTATIONAL STUDIES ON THE BINDING AND DYNAMICS OF THE OSH4 PROTEIN OF YEAST AND A MODEL YEAST MEMBRANE SYSTEM

Abstract

Osh4 is an oxysterol binding protein homologue found in yeast that is essential for the intracellular transport of sterols. It has been proposed that Osh4 acts as a lipid transport protein, binding a single sterol residue and transporting it from the endoplasmic reticulum to the plasma membrane. The dynamics of Osh4 as well as ergosterol binding was observed using molecular dynamics simulations. Blind docking of several model lipid head group moieties was used to detect potential binding regions along the Osh4 surface favorable towards phospholipid interaction. Models frequently docked to a lysine-rich region on the side of the protein's β-barrel. A model ergosterol-containing membrane system for yeast was also constructed and simulated using molecular dynamics, and an improvement to the deuterium order parameters was observed over previous models. Understanding how Osh4 attaches to cellular membranes will lead to a clear understanding of how this protein transports sterols in vivo.