Identification of Rtg2P Functional Domain Involved in Retrograde Signaling in Saccharomyces Cerevisiae
AdvisorGordon, Donna M.
CommitteeStewart Jr., James A.
In S. cerevisiae, the accumulation of dysfunctional mitochondria activates a retrograde signal that is mediated through multiple cytosolic regulators. Central to activation is the cytosolic regulator Rtg2p which through its interaction with Mks1p, promotes the nuclear translocation of Rtg1p/3p. Nuclear localized Rtg1p/3p promotes transcription of target genes. Prior work has shown Rtg2p interaction with Mks1p is required for downstream signaling, however the Mks1p binding site within Rtg2p is unknown. To identify this motif, random mutations were generated in RTG2 and a red-white screening strategy was used to assess 14,001 clones. Sequence analysis identified four mutants with amino acid mutations in the carboxy-terminus of Rtg2p that gave rise to defects in CIT2 transcription and loss of Mks1p interaction. Relative to RTG2, all mutants had reduced Rtg2p protein half-lives. Together these results suggest that the carboxy-terminal domain of Rtg2p is essential for retrograde signaling as it may contain the Mks1p binding site.