PMT1 deficiency extends the shortened replicative lifespan of TED1-deficient yeast in a Hac1p-dependent manner.

Protein O-mannosyltransferase-1 (Pmt1p) deficiency extends the replicative lifespan (RLS) of Saccharomyces cerevisiae, which is related to the activation of the unfolded protein response (UPR), an important pathway for alleviating endoplasmic reticulum (ER) stress. Trafficking of Emp24p/Erv25p-dependent cargo disrupted 1 (Ted1p) has been reported as a binding partner of yeast Pmt1p. We explored the potential relationship between Pmt1p and Ted1p in the cell lifespan and ER stress responses. The TED1-deleted strain (ted1Δ) had a shorter RLS with no increase in UPR activity. However, PMT1 deficiency prolonged the short lifespan of ted1Δ in a manner dependent on Hac1p, an upstream transcription factor of the UPR pathway. In addition, PMT1 deficiency enhanced the UPR activity and alleviated the ER stress resistance of the ted1Δ strain. Thus, the enhanced UPR activity was hypothesized to explain the longevity of the pmt1Δted1Δ strain, but this long-lived pmt1Δted1Δ strain showed decreased ER stress resistance compared with the short-lived ted1Δ strain. Taken together, our results suggest a possible relationship between PMT1 and TED1 regarding lifespan regulation and the ER stress response.