title: Stress exposure results in increased peroxisomal levels of yeast Pnc1 and Gpd1, which are imported via a piggy-backing mechanism.
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 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.
authors.affiliation: Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, P.O. Box 11103, 9700CC Groningen, The Netherlands. Electronic address: s.kumar@rug.nl.
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Kumar Choudhry
authors.affiliation: Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, P.O. Box 11103, 9700CC Groningen, The Netherlands. Electronic address: ritika.singh@rug.nl.
authors.forename: Ritika
authors.initials: R
authors.lastname: Singh
authors.affiliation: Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, P.O. Box 11103, 9700CC Groningen, The Netherlands. Electronic address: c.p.williams@rug.nl.
authors.forename: Chris P
authors.initials: CP
authors.lastname: Williams
authors.affiliation: Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, P.O. Box 11103, 9700CC Groningen, The Netherlands. Electronic address: i.j.van.der.klei@rug.nl.
authors.forename: Ida J
authors.initials: IJ
authors.lastname: van der Klei
mesh_terms: D050536:Glycerol-3-Phosphate Dehydrogenase (NAD+) / Q000235:genetics / Q000378:metabolism*; D009535:Nicotinamidase / Q000235:genetics / Q000378:metabolism*; D000074437:Peroxisomal Targeting Signal 2 Receptor; D020675:Peroxisomes / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D000074437:Peroxisomal Targeting Signal 2 Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; C568531:GPD1 protein, S cerevisiae; D050536:Glycerol-3-Phosphate Dehydrogenase (NAD+); D009535:Nicotinamidase; C474330:PNC1 protein, S cerevisiae
keywords: Glycerol phosphate dehydrogenase; Matrix protein import; Nicotinamidase; Peroxisome; Piggy-back import; Saccharomyces cerevisiae