Farnesylation of Pex19p Is Required for Its Structural Integrity and Function in Peroxisome Biogenesis
Farnesylation of Pex19p Is Required for Its Structural Integrity and Function in Peroxisome Biogenesis
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DOI：
10.1074/jbc.m109.016584
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发表时间：
2009-07-31
影响因子：
4.8
通讯作者：
Erdmann, Ralf
中科院分区：
文献类型：
--
作者：
Rucktaeschel, Robert;Thoms, Sven;Erdmann, Ralf
已知保守的CAAX盒Peroxin Pex19p可通过法尼化修饰。这种脂质修饰在过氧化物体生物发生中的可能参与，Pex19p法尼化的程度，以及它的分子功能尚不清楚或有争议。我们首先证明了完整的Pex19p池在体内是由法尼基转移酶处理的，并且这种修饰不依赖于过氧化体诱导或Pex19p膜锚定Pex3p。此外，PEX19的基因组突变证明，法尼化对于基质蛋白正确地进入过氧体是必不可少的，这被认为是由过氧体膜蛋白(PMP)靶向性或稳定性缺陷间接引起的。这一假设得到了以下观察的证实：Pex19p法尼化缺陷突变体的特征是显著的PMP(Pex11p，Ant1p)的稳态浓度显著降低，但过氧体输入机制的基本成分，特别是几乎从进口体中耗尽的环过氧化物素也显著减少。在体内和体外，只有当Pex19p被法尼化，亲和力在未经修饰的Pex19p和野生型Pex19p之间相差10倍时，PMP识别才有效。法尼斯化可能会引起Pex19p的构象变化。因此，Pex19p的异戊二烯基化有助于底物膜蛋白识别PMPs的拓扑发生，我们的结果强调了脂质修饰在蛋白质-蛋白质相互作用中的重要性。
The conserved CaaX box peroxin Pex19p is known to be modified by farnesylation. The possible involvement of this lipid modification in peroxisome biogenesis, the degree to which Pex19p is farnesylated, and its molecular function are unknown or controversial. We resolve these issues by first showing that the complete pool of Pex19p is processed by farnesyltransferase in vivo and that this modification is independent of peroxisome induction or the Pex19p membrane anchor Pex3p. Furthermore, genomic mutations of PEX19 prove that farnesylation is essential for proper matrix protein import into peroxisomes, which is supposed to be caused indirectly by a defect in peroxisomal membrane protein (PMP) targeting or stability. This assumption is corroborated by the observation that mutants defective in Pex19p farnesylation are characterized by a significantly reduced steady-state concentration of prominent PMPs (Pex11p, Ant1p) but also of essential components of the peroxisomal import machinery, especially the RING peroxins, which were almost depleted from the importomer. In vivo and in vitro, PMP recognition is only efficient when Pex19p is farnesylated with affinities differing by a factor of 10 between the non-modified and wild-type forms of Pex19p. Farnesylation is likely to induce a conformational change in Pex19p. Thus, isoprenylation of Pex19p contributes to substrate membrane protein recognition for the topogenesis of PMPs, and our results highlight the importance of lipid modifications in protein-protein interactions.