Inheritance of suppressors of the drug sensitivity of a NSR1 deleted yeast strain.
The NSR1 gene product is involved in ribosomal RNA production and ribosome assembly in Saccharomyces cerevisiae. Yeast strains carrying a deletion of the NSR1 gene have a defect in rRNA processing, an aberrant ribosome profile and are sensitive to the drug paromomycin. This paper reports the isolation and characterization of spontaneous suppressors of the paromomycin sensitivity. Such suppressors could be isolated at very high frequency and do not exhibit straightforward single-gene inheritance patterns. The suppressors are not influenced by non-Mendelian factors such as psi or rho. Through a replacement of chromosomal rDNA with a plasmid rDNA system, I show that suppression of paromomycin sensitivity is mediated by rDNA. Swapping wild-type plasmid rDNA for chromosomal rDNA can reverse the suppression, but the effect does not appear to be due to amplification of rDNA or amplification of a pre-existing mutant rDNA copy.
Zabetakis
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Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, Washington, DC 20375, USA. dan@cbmse.nrl.navy.mil
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004271:DNA, Fungal / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis / Q000235:genetics; D004352:Drug Resistance, Microbial; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D008826:Microbial Sensitivity Tests; D009687:Nuclear Proteins; D010303:Paromomycin / Q000494:pharmacology*; D016601:RNA-Binding Proteins; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic
D000900:Anti-Bacterial Agents; D004271:DNA, Fungal; D004275:DNA, Ribosomal; D005656:Fungal Proteins; C068036:NSR1 protein, S cerevisiae; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D010303:Paromomycin