Open AccessOver‐expression of the cercosporin facilitator protein, CFP , in Cercospora kikuchii up‐regulates production and secretion of cercosporin
Author(s) -
Upchurch Robert G,
Rose Mark S,
Eweida Mohamed
Publication year - 2001
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2001.tb10868.x
Subject(s) - biology , major facilitator superfamily , microbiology and biotechnology , secretion , toxin , gene , virulence , complementation , wild type , mutant , genetics , biochemistry
CFP ( c ercosporin f acilitator p rotein), 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, predominately 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.