A stable yeast strain efficiently producing cholesterol instead of ergosterol is functional for tryptophan uptake, but not weak organic acid resistance
Sterols are major lipids in eukaryotes and differ in their specific structure between species. Both cholesterol and ergosterol can form liquid ordered domains in artificial membranes. We reasoned that substituting the main sterol ergosterol by cholesterol in yeast should permit domain formation and discriminate between physical and sterol structure-dependent functions. Using a cholesterol-producing yeast strain, we show that solute transporters for tryptophan and arginine are functional, whereas the export of weak organic acids via Pdr12p, a multi-drug resistance family member, is not. The latter reveals a sterol function that is probably dependent upon a precise sterol structure. We present a series of novel yeast strains with different sterol compositions as valuable tools to characterize sterol function and use them to refine the sterol requirements for Pdr12p. These strains will also be improved hosts for heterologous expression of sterol-dependent proteins and safe sources to obtain pure cholesterol and other sterols.
► A stable yeast strain has been created synthesizing cholesterol instead of ergosterol. ► Cholesterol production allows the import of tryptophan into cells. ► Cholesterol does not support activity of the weak organic ion transporter PDR12. ► Strains producing other sterols have been produced. ► The methyl group in the sterol seems to be important for transporter activity.
Journal: Metabolic Engineering - Volume 13, Issue 5, September 2011, Pages 555–569