Balfe A, Hoefler G, Chen W W, Watkins P A
Kennedy Institute for Handicapped Children, Baltimore, Maryland 21205.
Pediatr Res. 1990 Mar;27(3):304-10. doi: 10.1203/00006450-199003000-00023.
Fibroblasts from patients with the inherited disorder Zellweger syndrome have few or no peroxisomes; multiple biochemical processes that normally occur in this organelle are defective. Rhizomelic chondrodysplasia punctata (RCDP) is another inherited disorder in which two unrelated peroxisomal metabolic processes, plasmalogen synthesis and phytanic acid oxidation, are impaired despite the normal appearance of peroxisomal structure. It was previously reported that one of the enzymes of peroxisomal fatty acid beta-oxidation, 3-ketoacyl-CoA thiolase (beta-keto-thiolase), was present in precursor rather than mature form in both of these diseases. Immunofluorescent staining for peroxisomal beta-ketothiolase showed the immunoreactivity to be localized in subcellular particles in fibroblasts from both Zellweger syndrome and RCDP patients, even though the former lack normal peroxisomes. Immunoblot studies were performed to determine the subcellular location of the thiolase precursor in fractionated fibroblasts from Zellweger and RCDP patients. In both disorders, thiolase immunoreactivity was detected in subcellular fractions having a lower density than normal peroxisomes and mitochondria, and was resistant to digestion by proteinase K. The density of the thiolase precursor-containing fractions was similar to that of peroxisomal membrane "ghost" fractions recently described by Santos et al. (J Biol Chem 263:10502-10509, 1988). Our results suggest that these are not empty membrane vesicles but contain at least one peroxisomal matrix protein. Furthermore, they exist not only in cells in which normal peroxisomes fail to form (Zellweger syndrome), but also in some cells which have catalase-containing peroxisomes (RCDP).
患有遗传性疾病泽尔韦格综合征（Zellweger syndrome）的患者的成纤维细胞几乎没有或根本没有过氧化物酶体；通常在这个细胞器中发生的多个生化过程存在缺陷。肢根型点状软骨发育不良（Rhizomelic chondrodysplasia punctata，RCDP）是另一种遗传性疾病，尽管过氧化物酶体结构外观正常，但两个不相关的过氧化物酶体代谢过程，即缩醛磷脂合成和植烷酸氧化，却受到损害。先前有报道称，在这两种疾病中，过氧化物酶体脂肪酸β氧化的一种酶，即3-酮酰基辅酶A硫解酶（β-酮硫解酶），以前体而非成熟形式存在。过氧化物酶体β-酮硫解酶的免疫荧光染色显示，免疫反应性定位于泽尔韦格综合征和RCDP患者成纤维细胞的亚细胞颗粒中，尽管前者缺乏正常的过氧化物酶体。进行免疫印迹研究以确定硫解酶前体在来自泽尔韦格和RCDP患者的分级分离的成纤维细胞中的亚细胞定位。在这两种疾病中，硫解酶免疫反应性在密度低于正常过氧化物酶体和线粒体的亚细胞级分中被检测到，并且对蛋白酶K的消化具有抗性。含有硫解酶前体的级分的密度与Santos等人最近描述的过氧化物酶体膜“空壳”级分的密度相似（《生物化学杂志》263:10502 - 10509，1988）。我们的结果表明，这些不是空的膜泡，而是至少含有一种过氧化物酶体基质蛋白。此外，它们不仅存在于正常过氧化物酶体无法形成的细胞（泽尔韦格综合征）中，也存在于一些含有过氧化氢酶的过氧化物酶体的细胞（RCDP）中。
