title: Expression of the cercosporin toxin resistance gene ( CRG1) as a dicistronic mRNA in the filamentous fungus Cercospora nicotianae.
abstract: The CRG1 gene in Cercospora nicotianae encodes a transcription factor and is required for cercosporin toxin resistance and production. Cloning and sequencing of the downstream region of the CRG1 gene led to the discovery of an adjacent gene ( PUT1) encoding a putative uracil transporter. Expression of CRG1 and PUT1 as assessed by Northern analysis indicated that, in addition to the expected monocistronic mRNAs (2.6 kb and 2.0 kb, respectively), a common 4.5-kb mRNA could be identified, using either a CRG1 or a PUT1 gene probe. The 2.6-kb transcript identified only by the CRG1 probe was expressed constitutively, whereas the 2.0-kb transcript identified only by the PUT1 probe was differentially expressed in various media. Four cDNA clones containing CRG1, PUT1, and the CRG1- PUT1 intergenic region were identified as part of the products from the 4.5-kb transcript. Both the 4.5-kb and 2.6-kb transcripts were not detectable in three crg1-disrupted mutants, using the CRG1 probe. The 2.0-kb transcript, but not the 4.5-kb one was detected using the PUT1 probe in the three crg1-disrupted mutants. Taken together, we conclude that the 4.5-kb transcript is a dicistronic mRNA of both CRG1 and PUT1 in the fungus C. nicotianae. This is the first example of a dicistronic mRNA identified in filamentous fungi.
authors.affiliation: Citrus Research and Education Center and Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, 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: Marilyn
authors.initials: M
authors.lastname: Ehrenshaft
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004351:Drug Resistance / Q000235:genetics; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D015870:Gene Expression; D005796:Genes; D016681:Genome, Fungal; D008969:Molecular Sequence Data; D033704:Nucleotide Transport Proteins / Q000235:genetics / Q000378:metabolism; D010569:Perylene / Q000031:analogs & derivatives* / Q000494:pharmacology; D012331:RNA, Fungal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D005656:Fungal Proteins; D033704:Nucleotide Transport Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D014157:Transcription Factors; D010569:Perylene; C026363:cercosporin