title: The CRG1 gene required for resistance to the singlet oxygen-generating cercosporin toxin in Cercospora nicotianae encodes a putative fungal transcription factor.
abstract: The Cercospora nicotianae CRG1 gene is involved in cellular resistance to the perylenequinone toxin, cercosporin, that generates highly toxic singlet oxygen upon exposure to light. The entire open reading frame (ORF) of CRG1 was isolated and sequenced. The gene contains an ORF of 1950bp including a 65-bp intron. The predicted 650 amino acid CRG1 protein contains a Cys(6)Zn(2) binuclear cluster DNA-binding motif with homology to various fungal regulatory proteins, indicating that CRG1 may act functionally as a transcription activator. Targeted gene disruption of CRG1 resulted in mutants that are partially sensitive to cercosporin and reduced in cercosporin production. Genetic complementation revealed that CRG1 fully restored cercosporin resistance, but only slightly restored cercosporin production in a UV-derived mutant (CS10) containing a single nucleotide substitution in crg1. Complementation of a crg1-null mutant, however, yielded strains that are similar to the wild-type in both phenotypes. These results indicate that the transcription regulator CRG1 is involved in the activation of genes associated with cercosporin resistance and production in the fungus Cercospora nicotianae.
authors.affiliation: Citrus Research and Education Center and Department of Plant Pathology, IFAS, University of Florida, Lake Alfred, FL 33850, USA. krchung@lal.ufl.edu
authors.forename: Kuang-Ren
authors.initials: KR
authors.lastname: Chung
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Daub
authors.forename: Karl
authors.initials: K
authors.lastname: Kuchler
authors.forename: Christoph
authors.initials: C
authors.lastname: Schüller
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000187:drug effects / Q000235:genetics*; D025141:Drug Resistance, Fungal; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010569:Perylene / Q000031:analogs & derivatives* / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors
chemical_list: C103756:CRG1 protein, Ustilago maydis; D005656:Fungal Proteins; D014157:Transcription Factors; D010569:Perylene; C026363:cercosporin