Informational content of mitochondrial DNA from a “low density” petite mutant of yeast

Abstract

Mitochondrial DNA from wild-type yeast Saccharomyces cerevisiae contains the genetic information for some mitochondrial tRNAs including tRNA ser and tRNA phe. In a “low density” petite mutant, mitochondrial DNA still retains the information for tRNA ser, while the information for tRNA phe is lost. The permanence of genetic information in this DNA containing only 3.6% G+C supports previous results concerning its intramolecular heterogeneity. An irregular distribution of G+C content along the molecule was further demonstrated by annealing experiments performed with DNA fragmented by sonication and fractionated on CsCl density gradient. These experiments show that the heavy fractions of the gradient preferentially anneal with mitochondrial seryl-tRNA.