Fig. 4.

Functional complementation of a null mutation of yeast PM H⁺-ATPase (strain YAK2) by the PHA1 gene from S. tuberosum cv. Spunta. (A) Serial dilutions (starting from an OD_600nm=1.7) of the following YAK2 yeast strains were spotted onto solid media containing glucose (MGlu-His, Leu, Trp) or galactose (MGal-His, Leu, Trp), buffered at pH 6.5: Control –, YAK2 transformed with empty YEplac181; Control +, YAK2 transformed with YEplac181-E14D, that expresses the constitutively active form of the PM H⁺-ATPase PMA2 Q42932 from N. plumbaginifolia under the yeast PMA1 promoter; PHA1∆N, YAK2 transformed with YEplac181-PHA1∆N that expresses a truncated, inactive form of PHA1, lacking the first 553 nucleotides of the N-terminus (devoid of the TGES motif) under the yeast PMA1 promoter; PHA1-1/2/3, YAK2 transformed with YEplac181-PHA1, that expresses PHA1 under the yeast PMA1 promoter (three different transformed yeast clones were used). (B) Serial dilutions (starting from an OD_600nm=1.7) of the following YAK2 yeast strains spotted onto solid media containing glucose (MGlu-His, Leu, Ura, Trp): Control –, PHA1–PHA3, and PHA1–PHA3 after 5-FOA treatment to eliminate the plasmid bearing the yeast PM H⁺-ATPase gene. Yeast strains were grown at 30 °C for 48 h.