Versicolorin synthesis by Aspergillus parasiticus: Regulation by temperature and zinc

Abstract

A mutant strain of Aspergillus parasiticus (ATCC 36537) was grown in shaken liquid culture at 23 or 37°C. The polyketide secondary metabolite versicolorin A was produced at the lower but not the higher temperature. Temperature upshift (23 → 37°C) arrested versicolorin synthesis; temperature downshift (37 → 23°C) allowed versicolorin synthesis to occur after a 6-h lag. Versicolorin synthesis after temperature downshift was blocked by addition of cycloheximide or actinomycin D at the time of temperature shift. Zn 2+ is known to be required for versicolorin synthesis, and Zn 2+ uptake must occur before temperature downshift. We suggest that a transcriptional event required for versicolorin synthesis occurs only in the presence of Zn 2+ and at temperatures below 37°C.