Prabudiansyah Irfan, Kusters Ilja, Caforio Antonella, Driessen Arnold J M
Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Nijenborgh 7, 9727 AG Groningen, The Netherlands; Zernike Institute for Advanced Materials, Nijenborgh 7, 9727 AG Groningen, The Netherlands.
Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Nijenborgh 7, 9727 AG Groningen, The Netherlands; Zernike Institute for Advanced Materials, Nijenborgh 7, 9727 AG Groningen, The Netherlands.
Biochim Biophys Acta. 2015 Oct;1848(10 Pt A):2050-6. doi: 10.1016/j.bbamem.2015.06.024. Epub 2015 Jun 27.
The bacterial Sec translocase in its minimal form consists of a membrane-embedded protein-conducting pore SecYEG that interacts with the motor protein SecA to mediate the translocation of secretory proteins. In addition, the SecYEG translocon interacts with the accessory SecDFyajC membrane complex and the membrane protein insertase YidC. To examine the composition of the native lipid environment in the vicinity of the SecYEG complex and its impact on translocation activity, styrene-maleic acid lipid particles (SMALPs) were used to extract SecYEG with its lipid environment directly from native Escherichia coli membranes without the use of detergents. This allowed the co-extraction of SecYEG in complex with SecA, but not with SecDFyajC or YidC. Lipid analysis of the SecYEG-SMALPs revealed an enrichment of negatively charged lipids in the vicinity of SecYEG, which in detergent assisted reconstitution of the Sec translocase are crucial for the translocation activity. Such lipid enrichment was not found with separately extracted SecDFyajC or YidC, which demonstrates a specific interaction between SecYEG and negatively charged lipids.
细菌Sec转运体的最简形式由一个嵌入膜中的蛋白质传导孔道SecYEG组成，它与动力蛋白SecA相互作用，介导分泌蛋白的转运。此外，SecYEG转运体与辅助性SecDFyajC膜复合物以及膜蛋白插入酶YidC相互作用。为了研究SecYEG复合物附近天然脂质环境的组成及其对转运活性的影响，使用苯乙烯-马来酸脂质颗粒（SMALPs）直接从天然大肠杆菌膜中提取SecYEG及其脂质环境，而不使用去污剂。这使得SecYEG能与SecA一起被共提取，但不能与SecDFyajC或YidC一起被共提取。对SecYEG-SMALPs的脂质分析显示，SecYEG附近富含带负电荷的脂质，在去污剂辅助的Sec转运体重组中，这些脂质对转运活性至关重要。单独提取的SecDFyajC或YidC未发现这种脂质富集，这表明SecYEG与带负电荷的脂质之间存在特异性相互作用。
