The import receptor for the peroxisomal targeting signal 2 (PTS2) in Saccharomyces cerevisiae is encoded by the PAS7 gene.

Abstract

The import of peroxisomal matrix proteins is dependent on one of two targeting signals, PTS1 and PTS2. We demonstrate in vivo that not only the import of thiolase but also that of a chimeric protein consisting of the thiolase PTS2 (amino acids 1–18) fused to the bacterial protein beta‐lactamase is Pas7p dependent. In addition, using a combination of several independent approaches (two‐hybrid system, co‐immunoprecipitation, affinity chromatography and high copy suppression), we show that Pas7p specifically interacts with thiolase in vivo and in vitro. For this interaction, the N‐terminal PTS2 of thiolase is both necessary and sufficient. The specific binding of Pas7p to thiolase does not require peroxisomes. Pas7p recognizes the PTS2 of thiolase even when this otherwise N‐terminal targeting signal is fused to the C‐terminus of other proteins, i.e. the activation domain of Gal4p or GST. These results demonstrate that Pas7p is the targeting signal‐specific receptor of thiolase in Saccharomyces cerevisiae and, moreover, are consistent with the view that Pas7p is the general receptor of the PTS2. Our observation that Pas7p also interacts with the human peroxisomal thiolase suggests that in the human peroxisomal disorders characterized by an import defect for PTS2 proteins (classical rhizomelic chondrodysplasia punctata), a functional homologue of Pas7p may be impaired.

Getting a camel through the eye of a needle: the import of folded proteins by peroxisomes

“…The PTS2 sequence is recognized by the Pex7p receptor ( Figure 1A) (Rehling et al, 1996). Rather less is known about Pex7p than Pex5p, as attempts to express and purify this protein have been met with limited success (Mukai and Fujiki, 2006;Pilar et al, 2008).…”

M-LP, Mpv17-like Protein, Has a Peroxisomal Membrane Targeting Signal Comprising a Transmembrane Domain and a Positively Charged Loop and Up-regulates Expression of the Manganese Superoxide Dismutase Gene

“…Recently, a number of studies have been carried out to investigate the mechanisms of peroxisomal biogenesis and protein import (6 -8). Targeting of peroxisomal matrix proteins is mediated by cytosolic receptors Pex5p and Pex7p that recognize the peroxisomal targeting signals PTS1, which consists of the sequence SKL (and conservative variants) at the carboxyl terminus (9,10), and PTS2, which consists of the consensus sequence (R/K)(L/V/I)X 5 (H/Q)(L/A) near the amino terminus (11,12), respectively. Whereas the targeting of peroxisomal matrix protein import has been well characterized, neither conclusive consensus sequence nor the receptor(s) involved in peroxisomal membrane protein targeting have been determined.…”

Antifungal activity of Saccharomyces cerevisiae peroxisomal 3-ketoacyl-CoA thiolase

“…Using MALDI-MS analysis, we confirmed that the purified protein sequence was identical to the amino acid sequence of yeast peroxisomal 3-ketoacyl-CoA thiolase, ScFox3 (GenBank accession number CAA86118) (data not shown). This protein is a typical PTS2 class protein related to peroxisome biogenesis (8). Transcripts of 3-ketoacyl-CoA thiolase are induced by treatment with certain stresses, such as senescence (10), fruit ripening (11), and pathogen exposure (12).…”

“…Proteins belonging to the PTS1 class contain a highly conserved tripeptide sequence, SKL, at the C-terminus; proteins of the PTS2 class contain a well conserved nine amino acid residue sequence, (R/K)-(K/V/A)-X5-(H/Q)-(L/A), at the N-terminal region that is removed after translocation (4,5). During the process of matrix protein translocation, PTS1 and PTS2 proteins are specifically recognized by the PTS1 receptor (Pex5p) (6, 7) and PTS2 receptor (Pex7p) (8), respectively.…”