Peroxisomal Pex11 is a pore-forming protein homologous to TRPM channels
Peroxisomal Pex11 is a pore-forming protein homologous to TRPM channels
复制标题
DOI：
10.1016/j.bbamcr.2015.11.013
复制
发表时间：
2016-02-01
影响因子：
5.1
通讯作者：
Antonenkov, Vasily D.
中科院分区：
文献类型：
--
作者：
Mindthoff, Sabrina;Grunau, Silke;Antonenkov, Vasily D.
已知超过30种蛋白质（Pex蛋白）参与过氧化物酶体的生物发生，过氧化物酶体是参与脂质和ROS代谢的普遍存在的氧化细胞器。Pex 11家族的同源蛋白负责过氧化物酶体的分裂和增殖。我们表明，酵母Pex 11是一个成孔蛋白共享序列相似性与TRAM阳离子选择性通道。在1.0 M KCl中电导A = 4.1 nS的Pex 11通道具有中度阳离子选择性（PK+/P-Cl- = 1.85），并且对电压依赖性关闭具有抗性。通道孔的估计大小（r类似于0.6 nm）支持Pex 11传导分子量低于300-400 Da的溶质的概念。Pex 11的过表达导致完整细胞中脂肪酸β-氧化的加速，但在相应的裂解物中没有。细胞中的β-氧化受到在选择性决定序列中携带点突变的Pex 11蛋白表达的影响。这些数据表明，代谢产物的Pex 11依赖性跨膜运输可能是脂肪酸β-氧化的限速步骤。这一结论通过分析表达具有模拟组成性磷酸化（S165 D，S167 D）或非磷酸化（S165 A，S167 A）蛋白的突变的Pex 11的酵母菌株中的β-氧化速率得到证实。结果表明，Pex 11的磷酸化是一种可以控制过氧化物酶体β-氧化速率的机制。我们的研究结果揭示了一个意想不到的功能，Pex 11作为一个非选择性通道负责跨过氧化物酶体膜的代谢物的转移。这些数据表明，过氧化物酶可能参与过氧化物酶体的代谢过程中，除了他们的角色在过氧化物酶体生物合成。(C)2015 Elsevier B. V.版权所有。
More than 30 proteins (Pex proteins) are known to participate in the biogenesis of peroxisomes-ubiquitous oxidative organelles involved in lipid and ROS metabolism. The Pex11 family of homologous proteins is responsible for division and proliferation of peroxisomes. We show that yeast Pex11 is a pore-forming protein sharing sequence similarity with TRAM cation-selective channels. The Pex11 channel with a conductance of A = 4.1 nS in 1.0 M KCl is moderately cation-selective (PK+/P-Cl- = 1.85) and resistant to voltage-dependent closing. The estimated size of the channel's pore (r similar to 0.6 nm) supports the notion that Pex11 conducts solutes with molecular mass below 300-400 Da. We localized the channel's selectivity determining sequence. Overexpression of Pex11 resulted in acceleration of fatty acids beta-oxidation in intact cells but not in the corresponding lysates. The beta-oxidation was affected in cells by expression of the Pex11 protein carrying point mutations in the selectivity determining sequence. These data suggest that the Pex11-dependent transmembrane traffic of metabolites may be a rate-limiting step in the beta-oxidation of fatty acids. This conclusion was corroborated by analysis of the rate of beta-oxidation in yeast strains expressing Pex11 with mutations mimicking constitutively phosphotylated (S165D, S167D) or unphosphorylated (S165A, S167A) protein. The results suggest that phosphorylation of Pex11 is a mechanism that can control the peroxisomal beta-oxidation rate. Our results disclose an unexpected function of Pex11 as a non-selective channel responsible for transfer of metabolites across peroxisomal membrane. The data indicate that peroxins may be involved in peroxisomal metabolic processes in addition to their role in peroxisome biogenesis. (C) 2015 Elsevier B.V. All rights reserved.