New antibiotic resistance Loci in the ribosomal region of yeast mitochondrial DNA.

A large number of mitochondrial antibiotic-resistant mutants have been isolated following mutagenesis with manganese. These include several different phenotypic classes of mutants, as distinguished by cross-resistance patterns, that have been found to be allelic at cap1 or ery1; some have been found to be heteroallelic.--Seven chloramphenicol-resistant mutants have been identified that are nonallelic by recombination tests with the three loci (cap1, spi1 and ery1) previously identified in the ribosomal region. Four of these are allelic with each other and define a new locus, cap3; two others are allelic and define another new locus, cap2; the seventh maps at yet a different locus, cap4. One new spiramycin-resistant mutant has been identified that defines still another new locus, spi2. A variety of genetic techniques have been used to map these loci within the ribosomal region of the mitochondrial genome.-Manganese has been shown to be effective in inducing the mutation from omega(-) to omega(n) in many mutants that experience a simultaneous mutation at the closely linked cap1 locus. The omega(n) mutation has also been described in the cap4 mutant, and this locus has been shown to be more closely linked to omega than cap1 is to omega.