Tamura Shigehiko, Yasutake Shinobu, Matsumoto Naomi, Fujiki Yukio
Department of Biology, Faculty of Sciences, Kyushu University Graduate School, Fukuoka 812-8581, Japan.
J Biol Chem. 2006 Sep 22;281(38):27693-704. doi: 10.1074/jbc.M605159200. Epub 2006 Jul 19.
Two AAA peroxins, Pex1p and Pex6p, are encoded by PEX1 and PEX6, the causal genes for peroxisome biogenesis disorders of complementation group 1 (CG1) and CG4, respectively. PEX26 responsible for peroxisome biogenesis disorders of CG8 encodes Pex26p, the recruiter of Pex1p.Pex6p complexes to peroxisomes. We herein assigned the binding regions between human Pex1p and Pex6p and elucidated pivotal roles of the AAA cassettes, called D1 and D2 domains, in Pex1p-Pex6p interaction and peroxisome biogenesis. ATP binding in both AAA cassettes but not ATP hydrolysis in D2 of both Pex1p and Pex6p was prerequisite for Pex1p-Pex6p interaction and their peroxisomal localization. The AAA cassettes, D1 and D2, were essential for peroxisome-restoring activity of Pex1p and Pex6p. In HEK293 cells, endogenous Pex1p was partly localized likely as a homo-oligomer in the cytoplasm, while Pex6p and Pex26p were predominantly localized on peroxisomes. Interaction of Pex1p with Pex6p conferred a conformational change and dissociation of the Pex1p oligomer. These results suggested that Pex1p possesses two distinct oligomeric forms, a homo-oligomer in the cytosol and a hetero-oligomer on peroxisome membranes, possibly playing distinct functions in peroxisome biogenesis.
两种AAA型过氧化物酶体蛋白Pex1p和Pex6p分别由PEX1和PEX6编码，它们分别是互补组1（CG1）和CG4的过氧化物酶体生物发生障碍的致病基因。负责CG8过氧化物酶体生物发生障碍的PEX26编码Pex26p，它是Pex1p.Pex6p复合物定位于过氧化物酶体的招募因子。我们在此确定了人Pex1p和Pex6p之间的结合区域，并阐明了称为D1和D2结构域的AAA盒在Pex1p-Pex6p相互作用和过氧化物酶体生物发生中的关键作用。Pex1p和Pex6p的两个AAA盒中的ATP结合而非D2中的ATP水解是Pex1p-Pex6p相互作用及其过氧化物酶体定位的先决条件。AAA盒D1和D2对于Pex1p和Pex6p的过氧化物酶体恢复活性至关重要。在HEK293细胞中，内源性Pex1p可能部分以同型寡聚体形式定位于细胞质中，而Pex6p和Pex26p主要定位于过氧化物酶体上。Pex1p与Pex6p的相互作用导致Pex1p寡聚体的构象变化和解离。这些结果表明，Pex1p具有两种不同的寡聚形式，一种是细胞质中的同型寡聚体，另一种是过氧化物酶体膜上的异型寡聚体，可能在过氧化物酶体生物发生中发挥不同的功能。
