Yonezawa H, Okamoto K, Tomokiyo K, Izumiya N
J Biochem. 1986 Nov;100(5):1253-9. doi: 10.1093/oxfordjournals.jbchem.a121831.
To elucidate the mode of antibacterial action by gramicidin S (GS), a detailed experiment on GS distribution on bacteria cells was carried out. 14C-Labeled gramicidin S ([14C]GS) was incubated with cells of Gram-positive Bacillus subtilis and Gram-negative Escherichia coli, and the amount of [14C]GS adsorbed on the cells was measured. Adsorption on B. subtilis cells was observed from 1 microgram/ml of [14C]GS. As the concentration of [14C]GS increased, the amount adsorbed on B. subtilis increased discontinuously, producing a curve which had three plateaus. On the other hand, [14C]GS was not easily adsorbed on E. coli cells at lower concentrations, but the amount adsorbed increased above 6 micrograms/ml, and the cells were temporarily saturated with GS at 10 micrograms/ml, which is the minimum inhibitory concentration for E. coli. The amount of [14C]GS adsorbed on the protoplast membrane of B. subtilis was the same as that of natural cells. However, the amount of [14C]GS adsorbed on the cell wall dropped to about 20% of that of natural bacteria. These facts indicate that GS is adsorbed on the cell membrane of bacteria particularly. The uptake of amino acid or glucose in B. subtilis was inhibited by GS. Therefore, it is concluded that GS damages the phospholipid bilayer of the cell membrane by adsorption, and prevents the functioning of the cell membrane. The amount of [14C]GS adsorbed on the spheroplast membrane of E. coli increased remarkably as compared with natural cells, even at a lower concentration of GS. The poor GS adsorption on E. coli cells may be due to the permeability barrier of the E. coli cell wall.
为阐明短杆菌肽S（GS）的抗菌作用模式，对GS在细菌细胞上的分布进行了详细实验。将14C标记的短杆菌肽S（[14C]GS）与革兰氏阳性枯草芽孢杆菌和革兰氏阴性大肠杆菌的细胞一起孵育，并测量吸附在细胞上的[14C]GS的量。在1微克/毫升的[14C]GS中观察到对枯草芽孢杆菌细胞的吸附。随着[14C]GS浓度的增加，吸附在枯草芽孢杆菌上的量不连续增加，产生了一条有三个平台的曲线。另一方面，在较低浓度下，[14C]GS不易吸附在大肠杆菌细胞上，但吸附量在6微克/毫升以上增加，并且在10微克/毫升时细胞被GS暂时饱和，这是大肠杆菌的最低抑菌浓度。吸附在枯草芽孢杆菌原生质膜上的[14C]GS的量与天然细胞相同。然而，吸附在细胞壁上的[14C]GS的量降至天然细菌的约20%。这些事实表明GS特别吸附在细菌的细胞膜上。枯草芽孢杆菌中氨基酸或葡萄糖的摄取受到GS的抑制。因此，可以得出结论，GS通过吸附破坏细胞膜的磷脂双层，并阻止细胞膜的功能。与天然细胞相比，即使在较低浓度的GS下，吸附在大肠杆菌球状体膜上的[14C]GS的量也显著增加。GS在大肠杆菌细胞上的吸附不良可能是由于大肠杆菌细胞壁的渗透屏障。
