EXPRESSION OF THE 3-PHOSPHOGLYCERATE KINASE GENE (PGKA) OF PENICILLIUM-CHRYSOGENUM

The sequence of the Penicillium chrysogenum pgkA gene promoter was determined up to 952 nucleotides (nt) 5' to the major transcriptional start point (position + 1), and contains a 38 bp pyrimidine-rich region within which transcription initiates at this and two minor sites (- 11, - 23). A 21 bp segment(- 99 to - 79) closely matches a region which is essential for the expression of the Aspergillus nidulans pgkA gene. A further region was found with similarity to sequences in other A. nidulans promoters possibly effecting response to carbon source. The terminator region of the P. chrysogenum pgkA gene was sequenced as far as 192 nt 3' to the stop codon and three polyadenylation sites were found at 94, 103 and 107 nt from this point, the first preceded by a possible polyadenylation signal. No transcription termination signal was found but several regions potentially forming stem-loop-structures were noted. A single 1.3 kb pgkA mRNA was readily detected by Northern blot analysis of total cellular RNA. Steady-state levels of pgkA mRNA were 1.5 to 2.0 times greater in mycelium harvested at similar stages of growth from medium containing the carbon sources acetate or quinate compared to glucose. A transformed strain of P. chrysogenum containing a fusion of the pgkA promoter to the Escherichia coli lacZ reporter gene integrated at the oliC locus was constructed, and beta-galactosidase activity monitored during growth of batch cultures in defined media: The pgkA promoter activity increased during exponential growth and was 2-3 times greater and increased most rapidly in mycelium grown on quinate or acetate compared to glucose. An equivalent strain of A. nidulans previously reported showed similar expression of the A, nidulans pgkA promoter. The P. chrysogenum pgkA promoter lacZ fusion transformed into A. nidulans at the qutE locus retained its broad pattern of control. This result indicates that the P. chrysogenum pgkA promoter contains the necessary protein binding sites for expression and regulation in A. nidulans.