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TRI12, a trichothecene efflux pump from Fusarium sporotrichioides: gene isolation and expression in yeast
- Alexander, N.J., McCormick, S.P., Hohn, T.M.
- MGG 1999 v.261 no.6 pp. 977
- Fusarium sporotrichioides, genes, proteins, polypeptides, secretion, trichothecenes, nucleotide sequences, amino acid sequences, complementary DNA, mutants, introns, antifungal properties, genetic transformation, gene expression, Saccharomyces cerevisiae, plasma membrane, phenotype, biological resistance
- Many of the genes involved in trichothecene toxin biosynthesis in Fusarium sprortrichioides are present within a gene cluster. Here we report the complete sequence for TRI12, a gene encoding a trichothecene efflux pump that is located within the trichothecene gene cluster of F. sporotrichioides. TRI12 encodes a putative polypeptide of 598 residues with sequence similarities to members of the major facilitator superfamily (MFS) and is predicted to contain 14 transmembrane-spanning segments. Disruption of TRI12 results in both reduced growth on complex media and reduced levels of trichothecene production. Growth of tri12 mutants on trichothecene-containing media is inhibited, suggesting that TRI12 may play a role in F. sporotrichioides self-protection against trichothecenes. Functional analysis of TRI12 was performed by expressing it in yeast strains that were co-transformed with a gene (TRI3) encoding a trichothecene 15-O-acetyltransferase. In the presence of the TR13 substrate, 15-decalonectrin, cultures of yeast strains carrying TRI12 and TR13 accumulated much higher levels of the acetylated product, calonectrin, than was observed for strains carrying TR13 alone. PDR5, a transporter of the ABC super-family, which is known to mediate trichothecene resistance in yeast, increased calonectrin accumulation in TRI12/TRI3 yeast strains but not in TR13 strains. These results confirm the involvement of TRI12 in the trichothecene efflux associated with toxin biosynthesis, and demonstrate the usefulness of yeast as a host system for studies of MFS-type transporters.