Letellier L, Howard S P, Buckley J T
Laboratoire des Biomembranes, URA CNRS 1116, Université Paris-Sud, Bâtiment 432, F-91405 Orsay, France.
J Biol Chem. 1997 Apr 25;272(17):11109-13. doi: 10.1074/jbc.272.17.11109.
Aeromonas spp. secrete the channel-forming protein proaerolysin across their inner and outer membranes in separate steps using the general secretion pathway. Here we show that treating A. hydrophila or A. salmonicida with the protonophore carbonyl cyanide m-chorophenyl hydrazone blocks the second step in transport, secretion across the outer membrane from the periplasm, under conditions where the ATP levels in the cell are no different than the levels in control, secreting cells. A threshold for DeltaPsi was observed in the region of 120 mV, below which secretion by both species was inhibited. Treatment of cells with arsenate, which lowered ATP levels but did not affect DeltaPsi, also reduced secretion from the periplasm, an indication that there is an ATP requirement for this step independent of the requirement for DeltaPsi. Secretion across the outer membrane was also arrested by increasing the osmotic pressure of the medium, even though cellular ATP levels and DeltaPsi were not affected. This may be due to disruption of some necessary association between the inner and outer membranes.
气单胞菌属细菌利用一般分泌途径，分两步将形成通道的蛋白前气溶素分泌穿过其内膜和外膜。在此我们表明，在细胞内ATP水平与对照分泌细胞中的水平无差异的条件下，用质子载体间氯苯腙处理嗜水气单胞菌或杀鲑气单胞菌会阻断转运的第二步，即从周质穿过外膜的分泌过程。在120 mV区域观察到一个跨膜电位差（ΔΨ）阈值，低于该阈值时，两种菌的分泌均受到抑制。用砷酸盐处理细胞，降低了ATP水平但不影响ΔΨ，这也减少了周质的分泌，这表明该步骤需要ATP，且与对ΔΨ的需求无关。即使细胞ATP水平和ΔΨ未受影响，通过增加培养基的渗透压也会阻止外膜的分泌。这可能是由于内膜和外膜之间某些必要的关联被破坏所致。
