Role of YGR076c in yeast mother cell-specific aging.
Gino Heeren, Stefanie Jarolim, Mark Rinnerthaler, Peter Laun, Elfriede Palle, Michael Breitenbach
Department of Cell Biology, University of salzburg, Helbrunnerstrasse 34, Salzburg, 5020, Austria
Old yeast mother cells were purified by centrifugal elutriation (Laun et al., Mol Microbiol 39:1166-73, 2001) and their transcriptome was compared with virgin daughter cells on DNA filter arrays. Strains deleted for genes corresponding to differentially expressed transcripts were systematically analyzed for resistance/sensitivity to oxidants and mother cell-specific lifespan. A strain deleted for YGR076c, a putative mitochondrial ribosomal protein, was respiratory deficient, hyper-resistant to peroxides, and displayed a 60% increase in median lifespan. The strain was devoid of mitochondrial DNA (rho-zero). An isogenic ethidium bromide induced rho-zero strain, on the contrary was oxidant-sensitive and did not show increased lifespan. We tested the retrograde response in our strain and found no CIT2 up-regulation on glucose, which possibly explains the lack of influence of respiratory deficiency on the lifespan. The results suggest to test the hypothesis that YGR076c could have a second function besides its role in the mitochondrial ribosomal machinery. We conclude that the respiratory deficiency caused by YGR076c deletion is not the cause for its oxidant resistance and increased longevity and another still unknown mechanism must be responsible.