LINEAR MITOCHONDRIAL DNAS FROM YEASTS - TELOMERES WITH LARGE TANDEM REPETITIONS

The terminal structure of the linear mitochondrial DNA (mtDNA) from th e yeast Candida parapsilosis was investigated. This mtDNA, 30 kb long, has symmetrical ends forming inverted terminal repeats. These repeats are made up of a variable number of tandemly repeating units of 738 b p each; the terminal nucleotide corresponds to a precise position with in the last repeat unit sequence. The ends had an open structure acces sible to enzymes, with a 5' single-stranded extension of about 110 nuc leotides. No circular forms were detected in the DNA preparations. Two other unrelated species, Pichia philodendra and Candida salmanticensi s also appear to have a linear mtDNA of similar organization. These li near DNAs (which we name Type 2 linear mtDNAs) are distinct from the p reviously described linear mtDNAs of yeasts whose termini are formed b y a closed hairpin loop (Type 1 linear mtDNA). The terminal structure of C. parapsilosis mtDNA is reminiscent of the linear mitochondrial ge nomes of the ciliate Tetrahymena although, in the latter, the telomeri c tandem repeat unit is considerably shorter.