Identification of genes induced in alkaloid-producing cultures of Claviceps sp.
In order to identify genes which are expressed during alkaloid synthesis in an axenic culture of Claviceps sp. (strain ATCC 26245), a cDNA library from a producing culture was differentially screened with cDNA from producing (cDNA+) and non-producing (cDNA-) cultures, respectively. Altogether, ten cDNA clones were obtained, the alkaloid-synthesis-correlated expression of which was confirmed by Northern analyses. Evaluation of their nucleotide and derived amino-acid sequences identified one gene unequivocally, coding for dimethylallyltryptophan-synthase (DMAT-S), the initial enzyme of the specific alkaloid pathway. For two other genes significant homologies to known fungal genes were detected: one clone showed homology to the Neurospora crassa ccg1 gene, coding for a clock-regulated putative general stress protein; seven cDNA clones, derived from the same gene, which is highly expressed under these conditions, contained typical hydrophobin domains and long stretches of asparagine/glycine repeats (like QID3 from Trichoderma harzianum), thus probably representing a cell-wall constituent. These data show that this is not only a successful approach to clone genes specific for the alkaloid-pathway of C. purpurea, but also of genes which might be involved in the differentiation of sclerotial hyphae, the prerequisite for alkaloid synthesis.
Arntz
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C
Institut für Botanik, Westfälische Wilhelms-Universität, Schlossgarten 3, D-48149 Münster, Germany.
Tudzynski
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D000470:Alkaloids / Q000378:metabolism*; D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000235:genetics; D002967:Claviceps / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D015723:Gene Library; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D000470:Alkaloids; D018076:DNA, Complementary