The Peroxisomal Matrix Import of Pex8p Requires Only PTS Receptors and Pex14p
The Peroxisomal Matrix Import of Pex8p Requires Only PTS Receptors and Pex14p
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DOI：
10.1091/mbc.e09-01-0037
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发表时间：
2009-08-15
影响因子：
3.3
通讯作者：
Subramani, Suresh
中科院分区：
文献类型：
--
作者：
Ma, Changle;Schumann, Uwe;Subramani, Suresh
巴斯德毕赤酵母（Pp）Pex 8 p是唯一已知的处于稳态的过氧化物酶体内过氧化物酶，其通过过氧化物酶体靶向信号（PTS）1型或PTS 2途径靶向过氧化物酶体。直到最近，所有进入过氧化物酶体基质的货物都被认为需要对接和真正有趣的新基因（RING）亚复合物，桥接这两个亚复合物的蛋白质和PTS受体再循环机制。然而，我们最近报道了PpPex 8 p通过PTS 2途径输入过氧化物酶体是Pex 14 p依赖性的，但不依赖于RING亚复合物（Zhang等人，2006年）。在进一步表征的过氧化物酶体膜相关的易位，我们表明，其他两个组件的对接子复合物，Pex 13 p和Pex 17 p，是不确定的进口Pex 8 p。此外，我们证明，进口Pex 8 p通过PTS 1途径也不需要环亚复合物或过氧化物酶体内Pex 8 p。在受体循环突变体（Delta pex 1、Delta pex 6和Delta pex 4）中，Pex 8 p主要是胞质的，因为Pex 5 p和Pex 20 p是不稳定的。然而，在Delta pex 4和Delta pex 6细胞中，当抗降解Pex 20 p突变体，血凝素（HA）-Pex 20 p（K19 R）过表达时，Pex 8 p进入过氧化物酶体残留物。我们的数据支持这样的想法，PpPex 8 p是一种特殊的货物，其易位到过氧化物酶体仅取决于PTS受体和Pex 14 p，而不是在过氧化物酶体内Pex 8 p，环亚复合物，或受体再循环机制。
Pichia pastoris (Pp) Pex8p, the only known intraperoxisomal peroxin at steady state, is targeted to peroxisomes by either the peroxisomal targeting signal (PTS) type 1 or PTS2 pathway. Until recently, all cargoes entering the peroxisome matrix were believed to require the docking and really interesting new gene (RING) subcomplexes, proteins that bridge these two subcomplexes and the PTS receptor-recycling machinery. However, we reported recently that the import of PpPex8p into peroxisomes via the PTS2 pathway is Pex14p dependent but independent of the RING subcomplex (Zhang et al., 2006). In further characterizing the peroxisome membrane-associated translocon, we show that two other components of the docking subcomplex, Pex13p and Pex17p, are dispensable for the import of Pex8p. Moreover, we demonstrate that the import of Pex8p via the PTS1 pathway also does not require the RING subcomplex or intraperoxisomal Pex8p. In receptor-recycling mutants (Delta pex1, Delta pex6, and Delta pex4), Pex8p is largely cytosolic because Pex5p and Pex20p are unstable. However, upon overexpression of the degradation-resistant Pex20p mutant, hemagglutinin (HA)-Pex20p(K19R), in Delta pex4 and Delta pex6 cells, Pex8p enters peroxisome remnants. Our data support the idea that PpPex8p is a special cargo whose translocation into peroxisomes depends only on the PTS receptors and Pex14p and not on intraperoxisomal Pex8p, the RING subcomplex, or the receptor-recycling machinery.