Functional domains and dynamic assembly of the peroxin Pex14p, the entry site of matrix proteins
Functional domains and dynamic assembly of the peroxin Pex14p, the entry site of matrix proteins
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DOI：
10.1074/jbc.m600158200
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发表时间：
2006-04-14
影响因子：
4.8
通讯作者：
Fujiki, Y
中科院分区：
文献类型：
--
作者：
Itoh, R;Fujiki, Y
41-kDa膜锚定的过氧化物酶Pex 14 p作为过氧化物酶体靶向信号（PTS）受体介导的，基质蛋白的初始输入位点。我们在这里确定的功能域的Pex 14 p参与进口网站子复合物的组装。在pex 14中国仓鼠卵巢细胞突变体中恢复受损蛋白质输入所需的Pex 14 p的最小区域位于一级序列中的残基21-260。一个高度保守的N-末端区域，包括残基21-70，与PTS 1受体Pex 5 p，Pex 13 p和Pex 19 p相互作用，这是膜生物合成所必需的。N-末端残基21-140，包括在110-138处的疏水区段，用作拓扑序列。定点诱变，大小分级，和化学交联分析表明，卷曲螺旋结构域在残基156-197调节同源二聚体的Pex 14 p。此外，跨膜段中的AXXXA和GXXXG基序介导Pex 14 p的同聚寡聚化，引起高分子量复合物的组装，从而确保Pex 14 p依赖于Pex 13 p定位于过氧化物酶体。Pex 5 p、Pex 13 p和Pex 19 p与具有不同分子量的Pex 14 p同源寡聚物结合，而未装载货物的Pex 5 p显然分解Pex 14 p同源寡聚物。因此，Pex 14 p最有可能形成几种不同的过氧化物酶复合物参与过氧化物酶体基质蛋白的输入。
The 41-kDa membrane-anchored peroxin Pex14p functions as the peroxisome targeting signal (PTS) receptor-mediated, initial import site for matrix proteins. We here identify the functional domains of Pex14p involved in the assembly of import site subcomplexes. The minimal region of Pex14p required for restoring impaired protein import in pex14 Chinese hamster ovary cell mutant lies at residues 21-260 in the primary sequence. A highly conserved N-terminal region, encompassing residues 21-70, interacts with the PTS1 receptor Pex5p, Pex13p, and Pex19p that is essential for membrane biogenesis. N-terminal residues 21-140, including a hydrophobic segment at 110-138, function as a topogenic sequence. Site-directed mutagenesis, size fractionation, and chemical cross-linking analyses demonstrate that the coiled-coil domain at residues 156-197 regulates homodimerization of Pex14p. Moreover, AXXXA and GXXXG motifs in the transmembrane segment mediate homomeric oligomerization of Pex14p, giving rise to assembly of high molecular mass complexes and thereby assuring Pex13p-dependent localization of Pex14p to peroxisomes. Pex5p, Pex13p, and Pex19p bind to Pex14p homo-oligomers with different molecular masses, whereas cargo-unloaded Pex5p apparently disassembles Pex14p homo-oligomers. Thus, Pex14p most likely forms several distinct peroxin complexes involved in peroxisomal matrix protein import.