Inactivation of a single type-2A phosphoprotein phosphatase is lethal in Neurospora crassa

A PCR approach, employing the use of degenerate oligonucleotide mixtures, was used to isolate pph-1, a type-2A protein phosphatase (catalytic subunit)-encoding gene, from Neurospora crassa. The isolated single-copy gene is 1327 nucleotides in length, contains four putative introns and encodes a 310 amino-acid polypeptide. pph-1 is located between pdx-1 and col-4 on the right arm of N. crassa linkage group IV. pph-1 transcript levels are highest during the first hours of conidial germination. Failure to obtain viable progeny in which pph-1 had been inactivated via the repeat-induced point (RIP) mutation process, and evidence that nuclei harboring a disrupted pph-1 gene could only be maintained in a hererokaryon, indicated that a functional pph-1 gene is essential for fungal growth. This is the first report providing evidence that inactivation of a single type-2A protein phosphatase gene results in a lethal phenotype in fungi.