Differential protein import deficiencies in human peroxisome assembly disorders.
Differential protein import deficiencies in human peroxisome assembly disorders.
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DOI：
10.1083/jcb.125.4.755
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发表时间：
1994-05
影响因子：
7.8
通讯作者：
Tabak, H
中科院分区：
文献类型：
--
作者：
Motley, A;Hettema, E;Distel, B;Tabak, H
迄今为止，基质蛋白的两个过氧化物酶体靶向信号（PTSs）已经被很好地定义。PTS1包含羧基末端三肽SKL，存在于多种基质蛋白中，而PTS2仅存在于过氧化物酶硫酶中，并且包含在NH2末端可切割的前序中。我们研究了过氧化物酶体组装障碍患者成纤维细胞中PTS1和PTS2输入通路的功能完整性。测试的五个互补组中有三个显示PTS1和PTS2的重要性普遍下降。两个互补组的过氧化物酶体蛋白输入缺失程度不同：第一组细胞能将含有PTS1的报告蛋白输入过氧化物酶体，但不能将含有PTS2的报告蛋白输入过氧化物酶体；第四组细胞能将含有PTS2的报告蛋白输入异常的过氧化物酶体幽灵状结构。在IV组细胞中，内源性硫硫酶对蛋白酶降解具有保护作用，并且在其他互补组（包括i组的局部失调）中，其敏感性也支持了PTS2输入通路的完整性。通过免疫荧光、亚细胞分离、还有免疫电子显微镜。I组和IV组细胞的表型为高等真核生物的差异输入缺陷提供了第一个证据。这些表型类似于酿酒酵母过氧化物酶体组装突变体中发现的表型。
Two peroxisome targeting signals (PTSs) for matrix proteins have been well defined to date. PTS1 comprises a COOH-terminal tripeptide, SKL, and has been found in several matrix proteins, whereas PTS2 has been found only in peroxisomal thiolase and is contained within an NH2- terminal cleavable presequence. We have investigated the functional integrity of the import routes for PTS1 and PTS2 in fibroblasts from patients suffering from peroxisome assembly disorders. Three of the five complementation groups tested showed a general loss of PTS1 and PTS2 import. Two complementation groups showed a differential loss of peroxisomal protein import: group I cells were able to import a PTS1- but not a PTS2- containing reporter protein into their peroxisomes, and group IV cells were able to import the PTS2 but not the PTS1 reporter into aberrant, peroxisomal ghostlike structures. The observation that the PTS2 import pathway is intact only in group IV cells is supported by the protection of endogenous thiolase from protease degradation in group IV cells and its sensitivity in the remaining complementation groups, including the partialized disorder of group I. The functionality of the PTS2 import pathway and colocalization of endogenous thiolase with the peroxisomal membranes in group IV cells was substantiated further using immunofluorescence, subcellular fractionation, and immunoelectron microscopy. The phenotypes of group I and IV cells provide the first evidence for differential import deficiencies in higher eukaryotes. These phenotypes are analogous to those found in Saccharomyces cerevisiae peroxisome assembly mutants.