盐生盐杆菌在不同营养条件下紫膜蛋白形成的差异

用四种培养基培养产生紫膜极端嗜盐菌盐生盐杆菌（Ｈａｌｏｂａｃｔｅｒｉｕｍｈａｌｏｂｉｕｍ）菌株Ｒ１，通过超速离心和蔗糖密度梯度纯化紫膜，ＳＤＳ－ＰＧＡＥ后用考马斯亮蓝染色的结果显示其合成的紫膜蛋白的形式有所差异。从蛋白胨培养基上获得的紫膜有三条蛋白带，分子量约２６～２７５ｋＤ，而从复合培养基、合成培养基和人工海水培养基上获得的紫膜，仅呈现一条蛋白带，分子量约２６ｋＤ，即蛋白胨培养基上的成熟紫膜蛋白形式。ＷｅｓｔｅｒｎＢｌｏｔｉｎｇ的结果证明，在以上四种培养基上获得的纯化紫膜经ＳＤＳ－ＰＧＡＥ后考马斯亮蓝染色的条带确系紫膜蛋白，但还存在含量低于考马斯亮蓝染色灵敏度的紫膜蛋白带，从复合培养基、合成培养基和人工海水培养基所得紫膜在２８ｋＤ左右有一条浅带，但从蛋白胨培养基所得紫膜无此带；四种培养基所得紫膜在２３５ｋＤ左右都有一条浅带。可见，培养基营养成分的差别影响了紫膜蛋白的存在形式

Different protein forms of purple membrane produced by Halobacterium halobium under various nutritional condition]

The extremely halophilic bacterium, purple membrane producing Halobacterium halobium strain R1 were cultured in four liquid media which consist of different constituents. After the purple membrane is harvested by ultracentrification and purified by sucrose density gradient ultracentrification, and run on SDS-PAGE, the result of Coomassie blue staining showed different bR protein forms: three bands with molecule weight ranging from 26.0 to 27.5 kD in peptone medium, while only one band with MW 26.0 kD in other three media-complex, synthetic and artificial seawater media, which corresponded to the mature form in peptone medium. The result of Western blotting not only confirmed the different protein forms of Coomassie blue staining in the four media, but also gave additional bands that Coomassie blue can not detect due to its lower sensitivity: 1) in the complex, synthetic and artificial seawater media, a faint 28.0 kD band existed, while in the peptone medium it did not exist; and 2) in the four media, it appeared that a faint 23.0-24.0 kD band exited. The different bR protein forms of purple membrane which result from the difference of nutritional constituents in these four media might be caused by different precursor processing enzymes or different activities of precursor processing enzyme(s) under these different nutritional conditions.