CLONING AND CHARACTERIZATION OF THE GENE FOR THE CATALYTIC SUBUNIT OFCAMP-DEPENDENT PROTEIN-KINASE IN THE AQUATIC FUNGUS BLASTOCLADIELLA-EMERSONII

We have isolated and characterized cDNA and genomic DNA clones encodin g the catalytic subunit (C) of cAMP-dependent protein kinase in the aq uatic fungus Blastocladiella emersonii. The C-subunit amino acid seque nce derived from the nucleotide sequence predicts a basic polypeptide of 424 residues, excluding the initiator methionine, which by amino-te rminal sequence analysis has been shown to be absent from the mature p rotein. The Blastocladiella C presents a 70-amino-acid extension at th e amino terminus, when aligned to the mouse C alpha subunit, being one of the largest C subunits already characterized. The B. emersonii C-g ene-coding region is interrupted by three introns, ranging in size ove r 57-69 bp. The positions of the introns are quite different from thos e found in other species, suggesting a considerable amount of evolutio nary drift in the gene structure. The 5'-flanking region lacks recogni zable TATA or CCAAT sequences, is remarkably high in GC content (70%), and primer extension experiments indicate that transcription initiate s from multiple sites. Several sequence motifs were identified in the promoter region which could be involved in the developmental control o f this gene.