A unique repeated DNA sequence in the cyclosporin-producing strain of Tolypocladium inflatum (ATCC 34921)

Recombinant lambda clones containing repeated DNA sequences were isolated from the cyclosporin A-producing fungus Tolypocladium inflatum (ATCC 34921) by differential hybridization with total fungal DNA and rDNA probes. From this survey 1% of the lambda clones appeared to contain repeated sequences. Subsequent analysis led to the identification of a dispersed repetitive DNA element. It was named CPA element (cyclosporin production associated) and appears to be strain specific, since it is absent from other related strains or fungi. Hybridization with chromosomal restriction fragments indicates an equal distribution of the CPA element in the genome. The copy number was estimated to be between 20 and 30 per haploid genome. Sequence analysis of a 0.9-kb XhoI fragment from three copies of the CPA element revealed strong conservation of this sequence among all copies. A 200-bp region exhibits similarities to a repeated sequence from Zea diploperennis. The use of this DNA sequence as a molecular marker for identification of this cyclosporin-producing strain ATCC 34921 is discussed as is the relevance of repeated DNA sequences for rearrangements of fungal karyotypes.