Polyketide synthase gene pksM from Aspergillus terreus expressed during growth phase

The polyketide synthase gene pksM was detected in the genomic DNA library of Aspergillus terreus by hybridization with the 6-methylsalicylic acid synthase (6-MSAS) gene of Penicillium patulum as a probe. 9524 bp of the cloned DNA were sequenced and a 5.5 kb open reading frame was revealed. A single intron (62 bp) was identified in the conserved position. Two transcription start points were determined within the 5'-flanking region at 50 and 72 (major) bp upstream from the putative translation initiation codon ATG. The conserved active site motifs for ketosynthase, acyltransferase, dehydratase, ketoreductase and acyl carrier protein were found within the predicted polypeptide consisting of 1803 amino acids. Unlike the P. patulum 6-MSAS gene, the transcription of pksM from A. terreus was observed in the middle of the vegetative growth phase.