Structure and expression of fungal calmodulin gene.

I report on the isolation, structural analysis, and in vivo expression patterns of a fungal calmodulin gene. The gene is intronless and encodes a protein of 148 amino acid residues that is 92% homologous with vertebrate calmodulins. Through S1 nuclease transcript mapping, it was determined that the cloned gene (a) is transcribed in vivo, (b) has a 5'-untranslated region of about 400 nucleotides, and (c) has a 3'-untranslated end of about 300 nucleotides. Southern blot hybridization analysis of the genomic DNA and the cloned gene provide evidence for the existence of only one type of calmodulin gene in the organism. The amino acid sequence deduced from the DNA sequence shows that Achlya klebsiana calmodulin has amino acid substitutions that are a mix of those seen in calmodulins from invertebrates such as Drosophila and trypanosome when compared to mammalian calmodulins. Not surprisingly, it has less resemblance to calmodulins from Saccharomyces and Dictyostelium.