Resistance to antimycin A in yeast by amplification of ADH4 on a linear, 42 kb palindromic plasmid.

A yeast strain lacking a functional copy of ADH1 has been isolated that is resistant to antimycin A because of the presence of multiple copies of a nuclear gene, ADH4. The amplified copies of ADH4 exist on linear molecules 42 kb in length, which can be separated from chromosomal DNA by orthogonal-field-alternation gel electrophoresis. These amplified molecules are palindromes that reanneal rapidly after denaturation to form linear, snap-back molecules 21 kb in length. The amplified ADH4 sequences are bounded by telomere-homologous sequences. The chromosomal copy of ADH4 is the most distal marker on the left arm of chromosome VII, and the amplified ADH4-containing molecules appear to contain two copies of the region extending from ADH4 to the telomere.