Tommassen J, de Vrije T, de Cock H, Bosch D, de Kruijff B
Department of Molecular Cell Biology, University of Utrecht, The Netherlands.
J Cell Sci Suppl. 1989;11:73-83. doi: 10.1242/jcs.1989.supplement_11.6.
Several models for the transport of proteins across membranes predict a role for lipids. If these models are correct, then alterations in lipid metabolism may affect protein export and vice versa. We are investigating this possibility by studying Escherichia coli K-12 mutants with defects in protein export or phospholipid metabolism. A temperature-sensitive secA mutant, which is defective in protein export at 42 degrees C, exhibited severe pleiotropic effects on membrane biogenesis. Incubation of this strain at 42 degrees C resulted in the appearance of intracytoplasmic membranes, in alterations in lipopolysaccharide structure and in decreased cardiolipin and C18:1 fatty acid content. On the other hand, a pgsA mutant which is defective in the synthesis of acidic phospholipids, exhibited a protein export defect when studied in vivo or in vitro. These results are in agreement with a postulated role of membrane lipids in protein export.
几种蛋白质跨膜转运模型预测脂质发挥了作用。如果这些模型正确，那么脂质代谢的改变可能会影响蛋白质输出，反之亦然。我们正在通过研究蛋白质输出或磷脂代谢存在缺陷的大肠杆菌K-12突变体来探究这种可能性。一种温度敏感型secA突变体在42℃时蛋白质输出存在缺陷，对膜生物合成表现出严重的多效性影响。该菌株在42℃下培养导致胞内膜的出现、脂多糖结构的改变以及心磷脂和C18:1脂肪酸含量的降低。另一方面，一种在酸性磷脂合成方面存在缺陷的pgsA突变体，在体内或体外研究时均表现出蛋白质输出缺陷。这些结果与膜脂质在蛋白质输出中的假定作用一致。
