Relationship between endoplasmic reticulum- and Golgi-associated calcium homeostasis and 4-NQO-induced DNA repair in Saccharomyces cerevisiae.

Calcium (Ca(2+)) is an important ion that is necessary for the activation of different DNA repair mechanisms. However, the mechanism by which DNA repair and Ca(2+) homeostasis cooperate remains unclear. We undertook a systems biology approach to verify the relationship between proteins associated with Ca(2+) homeostasis and DNA repair for Saccharomyces cerevisiae. Our data indicate that Pmr1p, a Ca(2+) transporter of Golgi complex, interacts with Cod1p, which regulates Ca(2+) levels in the endoplasmic reticulum (ER), and with Rad4p, which is a nucleotide excision repair (NER) protein. This information was used to construct single and double mutants defective for Pmr1p, Cod1p, and Rad4p followed by cytotoxic, cytostatic, and cell cycle arrest analyses after cell exposure to different concentrations of 4-nitroquinoline 1-oxide (4-NQO). The results indicated that cod1Delta, cod1Deltarad4Delta, and cod1Deltapmr1Delta strains have an elevated sensitivity to 4-NQO when compared to its wild-type (WT) strain. Moreover, both cod1Deltapmr1Delta and cod1Deltarad4Delta strains have a strong arrest at G(2)/M phases of cell cycle after 4-NQO treatment, while pmr1Deltarad4Delta have a similar sensitivity and cell cycle arrest profile when compared to rad4Delta after 4-NQO exposure. Taken together, our results indicate that deletion in Golgi- and ER-associated Ca(2+) transporters affect the repair of 4-NQO-induced DNA damage.