Identification and characterization of ENA ATPases HwENA1 and HwENA2 from the halophilic black yeast Hortaea werneckii.

Two genes, HwENA1 and HwENA2, which encode ENA-like ATPases in the extremely halotolerant black yeast Hortaea werneckii, were cloned and sequenced. Although the expression of both genes is responsive to salt, the transcription of the HwENA1 gene was induced at a higher level when the cells were exposed to salt stress, and the expression of HwENA2 gene was higher in the adapted cells, suggesting their different roles in maintaining alkali cation homeostasis. According to the phylogenetic tree based on the amino acid sequences, they represent a new group of fungal P-type ATPases. The comparison of both amino acid sequences with other fungal ENA ATPases, together with salt- and pH-responsive gene expression, suggests that newly identified ENA genes could be involved in maintaining low Na(+)/K(+) content in H. werneckii.