Rehling P, Skaletz-Rorowski A, Girzalsky W, Voorn-Brouwer T, Franse M M, Distel B, Veenhuis M, Kunau W H, Erdmann R
Division of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, School of Medicine, La Jolla, California 92093-0668, USA.
J Biol Chem. 2000 Feb 4;275(5):3593-602. doi: 10.1074/jbc.275.5.3593.
We report the characterization of ScPex8p, which is essential for peroxisomal biogenesis in Saccharomyces cerevisiae. Cells lacking Pex8p are characterized by the presence of peroxisomal membrane ghosts and mislocalization of peroxisomal matrix proteins of the PTS1 and PTS2 variety to the cytosol. Pex8p is tightly associated with the lumenal face of the peroxisomal membrane. Consistent with its intraperoxisomal localization, Pex8p contains a peroxisomal targeting signal 1, and it interacts with the PTS1 receptor Pex5p. However, the Pex5p/Pex8p association is also observed upon deletion of the PTS1 of Pex8p, suggesting that Pex8p contains a second binding site for Pex5p. The pex8Delta mutant phenotype and the observed PTS1-independent interaction with the PTS1 receptor suggest that Pex8p is involved in protein import into the peroxisomal matrix. In pex8Delta cells, the PTS1 and PTS2 receptor still associate with membrane bound components of the protein import machinery, supporting the assumption that the Pex8p function in protein translocation follows the docking event.
我们报道了酿酒酵母中过氧化物酶体生物合成所必需的ScPex8p的特性。缺乏Pex8p的细胞的特征是存在过氧化物酶体膜空壳，以及1型和2型过氧化物酶体靶向信号（PTS1和PTS2）的过氧化物酶体基质蛋白错误定位于细胞质中。Pex8p与过氧化物酶体膜的腔面紧密相关。与其过氧化物酶体内定位一致，Pex8p含有一个过氧化物酶体靶向信号1，并且它与PTS1受体Pex5p相互作用。然而，在缺失Pex8p的PTS1后也观察到Pex5p/Pex8p的结合，这表明Pex8p含有Pex5p的第二个结合位点。pex8Delta突变体表型以及观察到的与PTS1受体的不依赖于PTS1的相互作用表明，Pex8p参与蛋白质导入过氧化物酶体基质的过程。在pex8Delta细胞中，PTS1和PTS2受体仍与蛋白质导入机制的膜结合成分相关联，这支持了Pex8p在蛋白质转运中的功能发生在对接事件之后的假设。
