The regulation of mitochondrial DNA levels in Saccharomyces cerevisiae.

Mitochondrial DNA (mtDNA) synthesis can continue under conditions which block cell division and nuclear DNA (nDNA) synthesis, producing cells with several times the normal level of mtDNA. We have examined mtDNA synthesis in cultures recovering from such cell cycle blocks. Our results show that the rate of mtDNA synthesis is not affected either during a block of the cell cycle with α-factor or during recovery from a perturbation in the amount of mtDNA/cell induced by blocking the cell cycle with α-factor or cdc4. The normal mtDNA content was restored a period of several generations when permissive conditions were restored. These results suggest that mtDNA synthesis is coupled to cell growth.