Yeast molecular chaperone gene SSB2 is involved in the endoplasmic reticulum stress response
- 183 Downloads
The Saccharomyces cerevisiae chaperone gene SSB2 belongs to the Hsp70 family. Unlike other HSP70 genes, SSB2 gene expression is reduced after heat shock. It has been reported that Ssb2p can be cross-linked to ribosome-bound nascent polypeptide chains, suggesting a potential role of SSB2 in the endoplasmic reticulum (ER) stress response. In this study, SSB2-deletion and SSB2-overexpression yeast strains were generated and applied to explore the potential mechanism by which SSB2 is involved in the tunicamycin (TM)-induced ER stress response. We demonstrate for the first time that SSB2 deficiency results in reduced resistance to TM, while overexpression of SSB2 increases resistance to TM in an IRE1-HAC1 pathway-dependent manner; these observations are related to changes in intracellular unfolded protein response activities (under the TM-stressed condition). Additionally, SSB2 deletion induces early apoptosis and it may play a causal role in the shortened replicative life span of ssb2Δ mutants observed in this study. These findings highlight the involvement of SSB2 in ER stress responses and ageing in yeast.
KeywordsER stress Life span SSB2 Yeast
Chronological life span
Replicative life span
- S. cerevisiae
Unfolded protein response
This work was supported by the China National Natural Science Foundation (31101051, 81671399), the Ordinary University Innovation Team Construction Project of Guangdong Province (2015KCXTD022). We are grateful to Brian K. Kennedy (Buck Institute), Matt Kaeberlein and Brian M. Wasko (University of Washington) for technical assistance.
X-GL designed the experiments. WZ, H-JC, K-PQ, TZ and X-SH performed experiments. WZ wrote the manuscript. All authors discussed the results and commented on the manuscript.
Conflict of interest
The authors declare that they have no conflict of interest.
- Lopez N, Halladay J, Walter W, Craig EA (1999) SSB, encoding a ribosome-associated chaperone, is coordinately regulated with ribosomal protein genes. J Bacteriol 181:3136–3143Google Scholar
- Rinnerthaler M, Jarolim S, Heeren G, Palle E, Perju S et al (2006) MMI1 (YKL056c, TMA19), the yeast orthologue of the translationally controlled tumor protein (TCTP) has apoptotic functions and interacts with both microtubules and mitochondria. Biochim Biophys Acta 1757:631–638CrossRefGoogle Scholar
- Steffen KK, Kennedy BK, Kaeberlein M (2009) Measuring replicative life span in the budding yeast. J Vis Exp 28:1209Google Scholar