Functional Study On HAL5 In The Yeast Saccharomyces Cerevisiae

The regulation of intracellular ion concentrations is a fundamental property of living cells. Although many ion transporters have been identified in Saccharomyces cerevisiae, the systems that modulate their activities remain largely unknown. Both HAL5 and PTC1 play a key role for regulating the lithium tolerance, but the relationship between them have not been discovered. In our research, we have constructed a centromeric plasmid pHAC111-HAL5 and a multicopy plasmid pHAC181-HAL5. Here we show that overexpression of HAL5 can suppress the lithium sensitivity of the ptc1â–³and ptc1â–³ptc7â–³cells. This result indicates the genetic interaction between HAL5 and PTC1 under the Li+ stress in the yeast S. cerevisiae. Furthermore, deletion of PTC1 increase the expression level of the HAL5, suggesting that PTC1 negatively regulates the expression of HAL5. In addition, the phenotypes of overexpression of the HAL5 in the hal3 and ppz2 mutants provide evidence for the genetic relationship between HAL5,HAL3 and PPZ2.