Yeast molecular chaperone gene SSB2 is involved in the endoplasmic reticulum stress response

• Published in: Antonie van Leeuwenhoek 2019-04, Vol.112 (4), p.589-598
• Main Authors: Zhao, Wei, Cui, Hong-Jing, Qiu, Kun-Pei, Zhou, Tao, Hong, Xiao-Shan, Liu, Xin-Guang
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; Aging; Antifungal Agents - pharmacology; Apoptosis; Apoptosis - drug effects; Baking yeast; Biomedical and Life Sciences; Cellular stress response; Crosslinking; Endoplasmic reticulum; Endoplasmic Reticulum Stress - drug effects; Gene expression; Heat shock; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Hsp70 protein; Life Sciences; Life span; Medical Microbiology; Microbiology; Original Paper; Plant Sciences; Protein folding; Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - physiology; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Soil Science & Conservation; Stress response; Stresses; Tunicamycin; Tunicamycin - pharmacology; Unfolded Protein Response - drug effects; Yeast; Yeasts
• ISSN: 0003-6072; 1572-9699
• DOI: 10.1007/s10482-018-1189-3

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.