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Applied and Environmental Microbiology, April 2002, p. 1524-1533, Vol. 68, No. 4
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.4.1524-1533.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Uric Acid Is a Genuine Metabolite of Penicillium cyclopium and Stimulates the Expression of Alkaloid Biosynthesis in This Fungus{dagger}

Florian Helbig, Jörg Steighardt, and Werner Roos*

Department of Cellular Physiology, Institute of Pharmaceutical Biology, University of Halle, Halle, Germany

Received 13 August 2001/ Accepted 27 January 2002

On searching for endogenous, low-molecular-weight effectors of benzodiazepine alkaloid biosynthesis in Penicillium cyclopium uric acid was isolated from ethanolic or autoclaved mycelial extracts of this fungus. The isolation was based on a three-step high-pressure liquid chromatography procedure guided by a microplate bioassay, and uric acid was identified by mass spectrometry and the uricase reaction. Conidiospore suspensions that were treated with this compound during the early phase of outgrowth developed emerged cultures with an enhanced rate of alkaloid production. Uric acid treatment did not increase the in vitro measurable activity of the rate-limiting biosynthetic enzyme, cyclopeptine synthetase. However, these cultures displayed a reduced rate of uptake of the alkaloid precursor L-phenylalanine into the vacuoles of the hyphal cells as assayed in situ. It is suggested that the depressed capacity of vacuolar uptake caused by the contact of outgrowing spores with uric acid liberated from hyphal cells results in an enhanced availability of the precursor L-phenylalanine in the cytoplasm and thus accounts at least in part for the increase in alkaloid production.

* Corresponding author. Mailing address: Department of Cellular Physiology, Institute of Pharmaceutical Biology, University of Halle, 06120 Halle, Germany. Phone: 0345 5525010. Fax: 0345 5527006. E-mail: roos{at}pharmazie.uni-halle.de.

{dagger} Dedicated to Martin Luckner on the occasion of his retirement.

Applied and Environmental Microbiology, April 2002, p. 1524-1533, Vol. 68, No. 4
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.4.1524-1533.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.





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