title: Deletion of yeast CWP genes enhances cell permeability to genotoxic agents.
abstract: We have previously reported the development of a novel genotoxic testing system based on the transcriptional response of the yeast RNR3-lacZ reporter gene to DNA damage. This system appears to be more sensitive than other similar tests in microorganisms, and is comparable with the Ames test. In an effort to further enhance detection sensitivity, we examined the effects of altering major cell wall components on cell permeability and subsequent RNR3-lacZ sensitivity to genotoxic agents. Although inactivation of single CWP genes encoding cell wall mannoproteins had little effect, the simultaneous inactivation of both CWP1 and CWP2 had profound effects on the cell wall structure and permeability. Consequently, the RNR3-lacZ detection sensitivity is markedly enhanced, especially to high molecular weight compounds such as 4-nitroquinoline-N-oxide (> sevenfold) and phleomycin (> 13-fold). In contrast, deletion of genes encoding representative membrane components or membrane transporters had minor effects on cell permeability. We conclude that the yeast cell wall mannoproteins constitute the major barrier to environmental genotoxic agents and that their removal will significantly enhance the sensitivity of RNR-lacZ as well as other yeast-based genotoxic tests.
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072 China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Yuping
authors.initials: Y
authors.lastname: Liang
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: Heping
authors.initials: H
authors.lastname: Dai
authors.forename: Wei
authors.initials: W
authors.lastname: Xiao
mesh_terms: D001483:Base Sequence; D002463:Cell Membrane Permeability / Q000187:drug effects*; D004249:DNA Damage; D017931:DNA Primers; D017353:Gene Deletion; D005800:Genes, Fungal; D007763:Lac Operon; D008856:Microscopy, Fluorescence; D009152:Mutagenicity Tests; D009153:Mutagens / Q000633:toxicity*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000187:drug effects* / Q000235:genetics
chemical_list: D017931:DNA Primers; D009153:Mutagens; D029701:Saccharomyces cerevisiae Proteins