A new approach for the AAA peroxin research

AAA 过氧化物研究的新方法

基本信息

批准号：
18570111
负责人：
TAMURA Shigehiko
金额：
$ 2.59万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18570111/
关键词：
peroxisome organelle AAA protein Peroxin peroxisome biogenesis disorder 変異部位解析

项目摘要

Two peroxins, Pexlp and Pex6p, of the AAA protein family are responsible for peroxisome biogenesis disorders (PBDs) such as Zellweger syndrome of complementation group 1 (CG1) and CG4, respectively. These peroxins were recruited to peroxisomal membrane by Pex26p and suggested to be involved in the export from peroxisomes of Pex5p, the soluble recycling receptor for PTS1 matrix proteins. Furthermore, we recently reported that Pexlp was present partly in cytosol without forming a Pexlp-Pex6p-Pex26p complex. However, the molecular mechanism of the recycling system for Pex5p is not well understood. Therefore we investigated the role of AAA peroxins on peroxisomal membrane as well as in the cytosol. Co-immunoprecipitation and pull-down assays showed that Pex26p is competent to bind to Pex14p associated with Pex5p. The Pex26p-Pex14p complex was dissociated by Pexlp and Pex6p in an ATP-dependent manner. Blue-Native gel analysis of the cytosolic fraction from HEK293 cells and recombinant protein showed that Pex1p is mostly in a homo-trimer. In the assays for Pex5p oligomer structure in CHO-K1 cells, cytosolic Pex5p showed both dimer and monomer forms, although cytosolic Pex5p from Pex1p-deficient ZP107 cells was predominantly in a monomer form. Taken together, Pexlp-Pex6p complexes are likely to modulate the interaction of Pex26p and Pex14p, presumably releasing Pex5p from Pex14p. Furthermore, homo-trimer of Pexlp complexes were suggested to be involved in the conversion from a monomer to a dimer of cytosolic Pex5p. We discussed the sequential role of AAA peroxins in peroxisomal protein import and Pex5p recycling.

AAA 蛋白家族的两种过氧化物酶 Pex1p 和 Pex6p 分别负责过氧化物酶体生物发生障碍 (PBD)，例如互补组 1 (CG1) 和 CG4 齐薇格综合征。这些过氧化物被 Pex26p 招募到过氧化物酶体膜上，并被认为参与 Pex5p（PTS1 基质蛋白的可溶性再循环受体）过氧化物酶体的输出。此外，我们最近报道 Pexlp 部分存在于细胞质中，但没有形成 Pexlp-Pex6p-Pex26p 复合物。然而，Pex5p 回收系统的分子机制尚不清楚。因此，我们研究了 AAA 过氧化物酶在过氧化物酶体膜以及细胞质中的作用。免疫共沉淀和 Pull-down 测定表明，Pex26p 能够与 Pex5p 相关的 Pex14p 结合。 Pex26p-Pex14p 复合物被 Pexlp 和 Pex6p 以 ATP 依赖性方式解离。对 HEK293 细胞的胞质部分和重组蛋白进行 Blue-Native 凝胶分析表明，Pex1p 大部分为同源三聚体。在 CHO-K1 细胞中 Pex5p 寡聚体结构的测定中，胞质 Pex5p 显示二聚体和单体形式，尽管来自 Pex1p 缺陷的 ZP107 细胞的胞质 Pex5p 主要呈单体形式。总的来说，Pexlp-Pex6p 复合物可能调节 Pex26p 和 Pex14p 的相互作用，可能从 Pex14p 释放 Pex5p。此外，Pex1p复合物的同源三聚体被认为参与胞质Pex5p从单体到二聚体的转化。我们讨论了 AAA 过氧化物酶在过氧化物酶体蛋白输入和 Pex5p 回收中的连续作用。