Characterization and expression of two genes encoding isoforms of a putative Na, K-ATPase in the chytridiomycete Blastocladiella emersonii.

A P-type ATPase gene (BePAT1) from the aquatic fungus Blastocladiella emersonii, which surprisingly showed high similarity with the alpha-subunit of Na, K-ATPases from animal cells, has been reported recently [Biochim. Biophys. Acta 1383 (1998) 183]. In the present study, we describe the characterization of a second gene, denominated BePAT2, and show that these two genes have a different intron-exon structure but encode putative proteins with greater than 90% amino acid identity. Northern blot and multiplex reverse transcription and polymerase chain reaction (RT-PCR) assays have revealed that BePAT1 and BePAT2 genes have a non-coordinate, developmentally regulated expression during B. emersonii life cycle. Phosphoenzyme formation experiments using the immunopurified enzymes have indicated the presence of a Na, K-ATPase-like activity. Furthermore, immunofluorescence studies using B. emersonii zoospores localized the ATPases on the plasma membrane of these cells.