Genetics, Vol 122, 749-757, Copyright © 1989


INVESTIGATIONS

Extrachromosomal Elements Cause a Reduced Division Potential in nib 1 Strains of Saccharomyces cerevisiae

R. Sweeney and V. A. Zakian
Fred Hutchinson Cancer Research Center, 1124 Columbia Street, Seattle, Washington 98104

The nib 1 allele of yeast confers a sensitivity to an endogenous plasmid, 2{mu} DNA, in that nib 1 strains bearing 2{mu} DNA (cir(+)) exhibit a reduction in division potential. In the present study, the reduction in division potential characteristic of nib 1 cir(+) strains is shown to be dependent on the simultaneous presence of both the A and the D open reading frames of 2{mu} DNA as well as on the presence of an unidentified extrachromosomal element other than 2{mu} DNA. Furthermore, in nib 1 strains, an uncharacterized extrachromosomal element can cause a less severe reduction of division potential in the absence of intact 2{mu} DNA. Thus, the nib 1 allele may confer a generalized sensitivity to extrachromosomal elements.