Genetic dissection of a mitochondria-vacuole signaling pathway in yeast reveals a link between chronic oxidative stress and vacuolar iron transport.
Deletion of two homologous genes, MRS3 and MRS4, that encode mitochondrial iron transporters affects the activity of the vacuolar iron importer Ccc1. Ccc1 levels are decreased in Deltamrs3Deltamrs4 cells, but the activity of the transporter is increased, resulting is reduced cytosolic iron. Overexpression of CCC1 in Deltamrs3Deltamrs4 cells results in a severe growth defect due to decreased cytosolic iron, referred to as the mitochondria-vacuole signaling (MVS) phenotype. Mutants were identified that suppress the MVS growth defect, and FRA1 was identified as a gene that suppresses the MVS phenotype. Overexpression of FRA1 suppresses altered transition metal metabolism in Deltamrs3Deltamrs4 cells, whereas deletion of FRA1 is synthetically lethal with Deltamrs3Deltamrs4. Fra1 binds to Tsa1, which encodes a thioredoxin-dependent peroxidase. Deletion of TSA1 or TRR1 is synthetically lethal in Deltamrs3Deltamrs4 cells, suggesting that Deltamrs3Deltamrs4 cells generate reactive oxygen metabolites. The generation of reactive oxygen metabolites in Deltamrs3Deltamrs4 cells was confirmed by use of the reporter molecule 2',7'-dichlorodihydrofluorescein diacetate. These results suggest that mitochondria-induced oxidant damage is responsible for activating Ccc1 and that Fra1 and Tsa1 can reduce oxidant damage.
Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132, USA.
Liangtao
L
Li
Grace
G
Murdock
Dustin
D
Bagley
Xuan
X
Jia
Diane McVey
DM
Ward
Jerry
J
Kaplan
D015153:Blotting, Western; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D005452:Fluoresceins; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D017136:Ion Transport; D007501:Iron / Q000378:metabolism*; D008928:Mitochondria / Q000502:physiology*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014617:Vacuoles / Q000502:physiology*
C110400:2',7'-dichlorodihydrofluorescein diacetate; C089360:CCC1 protein, S cerevisiae; D027682:Cation Transport Proteins; C529265:FRA1 protein, S cerevisiae; D005452:Fluoresceins; D047908:Intracellular Signaling Peptides and Proteins; C066985:MRS3 protein, S cerevisiae; C066986:MRS4 protein, S cerevisiae; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D007501:Iron; D010544:Peroxidases; C496253:Tsa1 protein, S cerevisiae