Ergosterol reduction impairs mitochondrial DNA maintenance in S. cerevisiae

Area of Science:

• Cell Biology
• Biochemistry
• Yeast Genetics

Background:

• Sterols, including ergosterol, are vital lipids in cellular processes.
• Ergosterol biosynthetic enzymes (Erg proteins) in Saccharomyces cerevisiae localize to various cellular compartments.
• Organelle interactions are crucial for cellular function.

Purpose of the Study:

• To investigate the interplay between mitochondrial respiration and ergosterol production in yeast.
• To understand the role of Erg27p localization in cellular compartments.
• To determine ergosterol's role in maintaining mitochondrial DNA integrity.

Main Methods:

• Localization studies of Erg27p in respiratory competent and non-respiratory (rho°) yeast cells.
• Quantification of ergosterol content in wild-type and rho° cells.
• Analysis of mitochondrial DNA status following ergosterol pathway inhibition (ketoconazole) or gene deletion (∆erg27).
• Assessment of mitochondrial DNA loss suppression by exogenous ergosterol addition.

Main Results:

• Erg27p predominantly localizes to Lipid Droplets (LDs) in respiratory competent cells and the Endoplasmic Reticulum (ER) in non-respiratory cells.
• Rho° cells exhibit reduced ergosterol content compared to wild-type cells.
• Inhibition of ergosterol synthesis or deletion of ERG27 induces mitochondrial DNA loss (rho° production).
• Exogenous ergosterol addition rescues mitochondrial DNA loss in the ∆erg27 strain.

Conclusions:

• Mitochondrial respiration and ergosterol production are interconnected in yeast.
• Ergosterol is essential for the attachment of mitochondrial DNA to the inner mitochondrial membrane.
• Ergosterol plays a critical role in maintaining mitochondrial stability and function.