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Elsevier, Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1(1863), p. 148-156, 2016

DOI: 10.1016/j.bbamcr.2015.10.017

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Stress exposure results in increased peroxisomal levels of yeast Pnc1 and Gpd1, which are imported via a piggy-backing mechanism

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Abstract

Saccharomyces cerevisiae glycerol phosphate dehydrogenase 1 (Gpd1) and nicotinamidase (Pnc1) are two stress-induced enzymes. Both enzymes are predominantly localised to peroxisomes at normal growth conditions, but were reported to localise to the cytosol and nucleus upon exposure of cells to stress. Import of both proteins into peroxisomes depends on the peroxisomal targeting signal 2 (PTS2) receptor Pex7. Gpd1 contains a PTS2, however, Pnc1 lacks this sequence. Here we show that Pnc1 physically interacts with Gpd1, which is required for piggy-back import of Pnc1 into peroxisomes. Quantitative fluorescence microscopy analyses revealed that the levels of both proteins increased in the peroxisomes and in the cytosol upon exposure of cells to stress. However, upon exposure of cells to stress we also observed enhanced cytosolic levels of the control PTS2 protein thiolase, when produced under control of the GPD1 promoter. This suggests that these conditions cause a partial defect in PTS2 protein import, probably because the PTS2 import pathway is easily saturated.