N-terminal acetylation and replicative age affect proteasome localization and cell fitness during aging.
Bottom Line: By using a microscopy-based genome-wide screen, we identified genetic factors involved in these processes.Both relocalization of the proteasome and PSG formation were affected by two of the three N-acetylation complexes.These N-acetylation complexes also had different effects on the longevity of cells, indicating that each N-acetylation complex has different roles in proteasome location and aging.
Affiliation: Division of Cell Biology, Netherlands Cancer Institute and Netherlands Proteomics Center, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands.Show MeSH
Mentions: As proteasome composition and activity was found to influence longevity in starvation, we wondered whether proteasome localization would also correlate with cell fitness. Cellular fitness in starvation can be determined by assaying the ability of cells to restart their cell cycle when nutrients are added. This is determined by plating equal numbers of cells and quantifying the number of colony-forming units (CFUs). When grown in the presence of sufficient nutrients, the reproductive capacity of NatA- and NatC-deficient cells is similar to WT cells, whereas NatB-deficient cells show a lower reproductive capacity (Fig. 5A) (Polevoda et al., 1999). After a 5-day starvation period, both NatA- and NatB-deficient cells showed lower CFUs than wild-type cells, whereas the reproductive capacity in NatC-deficient cells seemed to be unaffected (Fig. 5B). Proteasome localization in NatA-deficient cells was similar to WT, unlike that in NatB-deficient cells. Given that NatA and NatB deficiency both decrease the number of CFUs measured, proteasome localization cannot be directly related to reproductive capacity in starvation.
Affiliation: Division of Cell Biology, Netherlands Cancer Institute and Netherlands Proteomics Center, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands.