title: Over-expression of the cercosporin facilitator protein, CFP, in Cercospora kikuchii up-regulates production and secretion of cercosporin.
abstract: CFP (cercosporin facilitator protein), a light-regulated gene from the soybean fungal pathogen Cercospora kikuchii, encodes the putative major facilitator transporter of the fungal polyketide cercosporin. Gene disruption of CFP in C. kikuchii strain Gus-3 resulted in dramatically reduced cercosporin production and virulence, and increased sensitivity to the toxin. Two C. kikuchii transformant strains (10-1 and 10-11) that over-produce cercosporin were recovered from the complementation of CFP gene-disrupted strain Gus-3. Southern analysis revealed that these strains contained multiple genomic copies of CFP and over-expressed CFP transcript and protein. Although 10-1 and 10-11 produce and secrete significantly elevated levels of cercosporin, they exhibit wild-type resistance to cercosporin, and maintain a wild-type pattern of light-regulated toxin accumulation. Restoration of wild-type cercosporin resistance in 10-1 and 10-11 suggests that CFP does contribute substantially to cercosporin resistance via toxin secretion. The three-fold increase in toxin accumulation, predominantly associated with the mycelium fraction of these CFP multi-copy strains, suggests that CFP may also have a significant, but unknown, role in regulating toxin production.
authors.affiliation: Agricultural Research Service, US Department of Agriculture, North Carolina State University, Raleigh, NC 27695, USA. greg_upchurch@ncsu.edu
authors.forename: R G
authors.initials: RG
authors.lastname: Upchurch
authors.forename: M S
authors.initials: MS
authors.lastname: Rose
authors.forename: M
authors.initials: M
authors.lastname: Eweida
mesh_terms: D001203:Ascomycota / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D025141:Drug Resistance, Fungal; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D005656:Fungal Proteins; D017353:Gene Deletion; D018628:Gene Dosage; D015966:Gene Expression Regulation, Fungal; D015151:Immunoblotting; D026901:Membrane Transport Proteins; D010569:Perylene / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D013025:Glycine max / Q000382:microbiology; D014158:Transcription, Genetic; D015854:Up-Regulation
chemical_list: D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; C400126:cercosporin transporter protein, Cercospora; D010569:Perylene; C026363:cercosporin