van't Hof R, van Klompenburg W, Pilon M, Kozubek A, de Korte-Kool G, Demel R A, Weisbeek P J, de Kruijff B
Department of Biochemistry of Membranes, University of Utrecht, The Netherlands.
J Biol Chem. 1993 Feb 25;268(6):4037-42.
The interaction of the precursor of the chloroplast protein ferredoxin with membrane lipids was studied in monolayer experiments in order to investigate the possible involvement of membrane lipids in the protein translocation process. The precursor efficiently and specifically inserts into a total lipid extract of its biological target the outer envelope membrane of chloroplasts. This interaction is mediated by the transit sequence as it can also be observed for the chemically prepared transit peptide of ferredoxin but neither for the ferredoxin apoprotein nor holoprotein. Interactions with the individual chloroplast lipids, monogalactosyl-diacylglycerol, sulfoquinovosyl-diacylglycerol, and phosphatidylglycerol are predominantly involved which corresponds to the results obtained for transit peptide fragments of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (van't Hof, R., Demel, R. A., Keegstra, K., and De Kruijff, B. (1991) FEBS Lett. 291, 350-354). No efficient interaction was obtained with digalactosyl-diacylglycerol and phosphatidylcholine, suggesting that a loose lipid headgroup packing due to small lipid headgroups and/or electrostatic repulsions facilitates efficient insertion. The observed preferences for interaction of the precursor and transit peptide of ferredoxin for the chloroplast outer envelope membrane lipid extract and the presequence of cytochrome c oxidase subunit IV for the mitochondrial outer membrane lipid extract indicate that targeting sequence-lipid interactions contribute to organelle-specific protein targeting.
为了研究膜脂在蛋白质转运过程中可能的作用，在单层实验中研究了叶绿体铁氧还蛋白前体与膜脂的相互作用。该前体能够高效且特异性地插入其生物学靶标——叶绿体外膜的总脂质提取物中。这种相互作用是由转运序列介导的，因为对于化学合成的铁氧还蛋白转运肽也能观察到这种现象，但对于铁氧还蛋白脱辅基蛋白或全蛋白则观察不到。与叶绿体中的个别脂质，即单半乳糖基二酰基甘油、磺基喹喔基二酰基甘油和磷脂酰甘油的相互作用占主导，这与1,5-二磷酸核酮糖羧化酶/加氧酶小亚基转运肽片段的研究结果一致（范特霍夫，R.，德梅尔，R. A.，基格斯特拉，K.，和德克鲁伊夫，B.（1991年）《欧洲生物化学学会联合会快报》291，350 - 354）。与二半乳糖基二酰基甘油和磷脂酰胆碱没有产生有效的相互作用，这表明由于脂质头部基团较小和/或静电排斥导致的松散脂质头部基团堆积有利于高效插入。观察到铁氧还蛋白前体和转运肽与叶绿体外膜脂质提取物的相互作用偏好，以及细胞色素c氧化酶亚基IV的前序列与线粒体外膜脂质提取物的相互作用偏好，表明靶向序列 - 脂质相互作用有助于细胞器特异性蛋白质靶向。
