A novel putative reductase (Cpd1p) and the multidrug exporter Snq2p are involved in resistance to cercosporin and other singlet oxygen-generating photosensitizers in Saccharomyces cerevisiae.
Phytopathogenic Cercospora species produce cercosporin, a photoactivated perylenequinone toxin that belongs to a family of photosensitizers which absorb light energy and produce extremely cytotoxic, reactive oxygen species. In this work, we used Saccharomyces cerevisiae as a model system for the identification and cloning of genes whose products mediate cercosporin detoxification. Two genesexpressed in high-copy number vectors conferred cercosporin resistance to an otherwise sensitive strain. One gene codes for Snq2p, a well-characterized multidrug, ABC-type, efflux protein. The other, designated CPD1 (Cercosporin Photosensitizer Detoxification), encodes a novel protein with significant similarity to the FAD-dependent pyridine nucleotide reductases. We showed that over-expression of either of these proteins can also mediate resistance to other singlet oxygen-generating compounds. The involvement of Snq2p and Cpd1p in photosensitizer detoxification reinforces previous observations which suggested that singlet oxygen acts on membrane lipids and that cellular resistance to cercosporin is mediated by a mechanism involving toxin efflux and/or toxin reduction.
Ververidis
P
P
Department of Crop Science, Plant Biochemistry & Biotechnology Laboratory, School of Agricultural Technology, Technological Educational Institute, P.O. Box 140, 71110 Heraklion, Crete, Greece. ververid@steg.teiher.gr
Davrazou
F
F
Diallinas
G
G
Georgakopoulos
D
D
Kanellis
A K
AK
Panopoulos
N
N
D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000502:physiology*; D010569:Perylene / Q000031:analogs & derivatives* / Q000633:toxicity*; D017319:Photosensitizing Agents / Q000037:antagonists & inhibitors; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D026082:Singlet Oxygen / Q000378:metabolism; D014170:Transformation, Genetic / Q000235:genetics
D018528:ATP-Binding Cassette Transporters; D005656:Fungal Proteins; D017319:Photosensitizing Agents; C101797:SNQ2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D026082:Singlet Oxygen; D010569:Perylene; C026363:cercosporin; C443623:AIF1 protein, S cerevisiae; D009247:NADH, NADPH Oxidoreductases