title: PAC1, a pH-regulatory gene from Fusarium verticillioides.
abstract: Fumonisins are a group of mycotoxins that contaminate maize and cause leukoencephalomalacia in equine, pulmonary edema in swine, and promote cancer in mice. Fumonisin biosynthesis in Fusarium verticillioides is repressed by nitrogen and alkaline pH. We cloned a PACC-like gene (PAC1) from F. verticillioides. PACC genes encode the major transcriptional regulators of several pH-responsive pathways in other filamentous fungi. In Northern blot analyses, a PAC1 probe hybridized to a 2.2-kb transcript present in F. verticillioides grown at alkaline pH. A mutant of F. verticillioides with a disrupted PAC1 gene had severely impaired growth at alkaline pH. The mutant produced more fumonisin than the wild type when grown on maize kernels and in a synthetic medium buffered at an acidic pH, 4.5. The mutant, but not the wild type, also produced fumonisin B(1) when mycelia were resuspended in medium buffered at an alkaline pH, 8.4. Transcription of FUM1, a gene involved in fumonisin biosynthesis, was correlated with fumonisin production. We conclude that PAC1 is required for growth at alkaline pH and that Pac1 may have a role as a repressor of fumonisin biosynthesis under alkaline conditions.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Flaherty
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Pirttilä
authors.forename: Burton H
authors.initials: BH
authors.lastname: Bluhm
authors.forename: Charles P
authors.initials: CP
authors.lastname: Woloshuk
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D004722:Endoribonucleases; D037341:Fumonisins / Q000302:isolation & purification; D005656:Fungal Proteins / Q000235:genetics*; D005670:Fusarium / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005798:Genes, Bacterial; D005809:Genes, Regulator; D006863:Hydrogen-Ion Concentration; D016133:Polymerase Chain Reaction / Q000379:methods
chemical_list: D017931:DNA Primers; D037341:Fumonisins; D005656:Fungal Proteins; D004722:Endoribonucleases