Creation of a hyperpermeable yeast strain to genotoxic agents through combined inactivation of PDR and CWP genes.
We previously established a genotoxicity detection system based on the transcriptional response of the yeast RNR3 gene to DNA damage. In order to further improve its sensitivity to genotoxicants, we have attempted to increase cell permeability by removing cell wall mannoproteins (CWPs). Here, we report that selected deletion of pleiotropic drug resistance (PDR) genes encoding membrane efflux transporters also enhanced cellular sensitivity to treatment by various genotoxic agents. Furthermore, we have validated our hypothesis that PDR and CWP protect cells through different mechanisms by demonstrating that simultaneous inactivation of the above two pathways resulted in a synergistic enhancement of assay sensitivity as measured by RNR3-lacZ expression and that this effect is at the cell permeability level. The quadruple mutation results in RNR3-lacZ assay sensitivity to tested chemicals that apparently surpasses the industry standard Ames test. We argue that this hyperpermeable yeast mutant strain would be suitable for other chemical-based genotoxic assays.
Zhang
Min
M
Institute of Hydrobiology, Chinese Academy of Sciences, Hubei, China.
Hanna
Michelle
M
Li
Jia
J
Butcher
Susan
S
Dai
Heping
H
Xiao
Wei
W
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D016588:Anticarcinogenic Agents / Q000633:toxicity; D002463:Cell Membrane Permeability / Q000187:drug effects; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D007763:Lac Operon / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D009152:Mutagenicity Tests / Q000379:methods; D009153:Mutagens / Q000633:toxicity*; D012262:Ribonucleoside Diphosphate Reductase / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
D018528:ATP-Binding Cassette Transporters; D016588:Anticarcinogenic Agents; D008562:Membrane Glycoproteins; D009153:Mutagens; D029701:Saccharomyces cerevisiae Proteins; C025363:mannoproteins; C517042:RNR3 protein, S cerevisiae; D012262:Ribonucleoside Diphosphate Reductase