Petite deletion map of the mitochondrial oxi3 region in Saccharomyces cerevisiae.

Fifty eight mitochondrial mutants (p + mit- mutants), all deficient in cytochrome oxidase activity and previously assigned to the genetic region oxi3 on the mitochondrial DNA, were mapped by the method of "petite deletion mapping". This procedure resulted in the identification of at least twenty one different classes of oxi3 mutants, which could be arranged in a linear order. Moreover, it provided a set of twenty three p- petite mutants, each containing a differentially deleted mit DNA segment included in the oxi3 region. The two sets of mutants, p+ oxi3- and p- oxi3+, will be of interest for a further genetic and physical analysis of this mitochondrial DNA segment which spans over about ten thousand base pairs and controls the subunit I of cytochrome oxidase.