A type 2A protein phosphatase gene from Aspergillus nidulans is involved in hyphal morphogenesis

A PCR-based approach, using degenerate oligonucleotide primers, was used to isolate fragments of two genes encoding type 2A protein phosphatases from the filamentous fungus, Aspergillus nidulans. The complete genomic sequence of one of these genes, pphA, was isolated and characterised. The pphA gene was predicted to encode a 329-residue protein which is about 85% identical to mammalian protein phosphatase 2A. Ectopic expression of the wild-type pphA+ gene slightly inhibited growth in some transformants; but a mutant form of pphA, in which R259 was mutated to Q, led to slow growth, delayed germ tube emergence and mitotic defects at low temperature. These results indicate that the pphA+ gene plays an important role in hyphal growth.