Hettema E H, Ruigrok C C, Koerkamp M G, van den Berg M, Tabak H F, Distel B, Braakman I
Department of Biochemistry, Academic Medical Center, 1105 AZ Amsterdam, The Netherlands.
J Cell Biol. 1998 Jul 27;142(2):421-34. doi: 10.1083/jcb.142.2.421.
The Saccharomyces cerevisiae DJP1 gene encodes a cytosolic protein homologous to Escherichia coli DnaJ. DnaJ homologues act in conjunction with molecular chaperones of the Hsp70 protein family in a variety of cellular processes. Cells with a DJP1 gene deletion are viable and exhibit a novel phenotype among cytosolic J-protein mutants in that they have a specific impairment of only one organelle, the peroxisome. The phenotype was also unique among peroxisome assembly mutants: peroxisomal matrix proteins were mislocalized to the cytoplasm to a varying extent, and peroxisomal structures failed to grow to full size and exhibited a broad range of buoyant densities. Import of marker proteins for the endoplasmic reticulum, nucleus, and mitochondria was normal. Furthermore, the metabolic adaptation to a change in carbon source, a complex multistep process, was unaffected in a DJP1 gene deletion mutant. We conclude that Djp1p is specifically required for peroxisomal protein import.
酿酒酵母DJP1基因编码一种与大肠杆菌DnaJ同源的胞质蛋白。DnaJ同源物在多种细胞过程中与Hsp70蛋白家族的分子伴侣协同作用。缺失DJP1基因的细胞能够存活，并且在胞质J蛋白突变体中表现出一种新的表型，即它们仅对一种细胞器——过氧化物酶体有特异性损伤。该表型在过氧化物酶体组装突变体中也很独特：过氧化物酶体基质蛋白在不同程度上错误定位于细胞质中，过氧化物酶体结构未能生长到完整大小，并表现出广泛的浮力密度范围。内质网、细胞核和线粒体的标记蛋白导入正常。此外，对碳源变化的代谢适应是一个复杂的多步骤过程，在DJP1基因缺失突变体中不受影响。我们得出结论，Djp1p是过氧化物酶体蛋白导入所特需的。
