THE STRUCTURE OF THE SMALL MITOCHONDRIAL-DNA OF KLUYVEROMYCES THERMOTOLERANS IS LIKELY TO REFLECT THE ANCESTRAL GENE ORDER IN FUNGI

Mapping the 23-kb circular mitochondrial DNA from the yeast Kluyveromy ces thermotolerans has shown that only one change occurs in the gene o rder in comparison to the 19-kb mtDNA of Candida (Torulopsis) glabrata . Sequence analysis of the mitochondrially encoded cytochrome oxidase subunit 2 gene reveals that despite their conserved gene order, the tw o small genomes are more distantly related than larger mtDNA molecules with multiple rearrangements. This result supports a previous observa tion that larger mitochondrial genomes are more prone to rearrange tha n smaller forms and suggests that the architecture of the two small mo lecules is likely to represent the structure of an ancestor.