Wiese A, Brandenburg K, Carroll S F, Rietschel E T, Seydel U
Department of Immunochemistry and Biochemical Microbiology, Center for Medicine and Biosciences, Research Center Borstel, Parkallee 10, D-23845 Borstel, Germany.
Biochemistry. 1997 Aug 19;36(33):10311-9. doi: 10.1021/bi970177e.
The mechanisms of interaction of the recombinant N-terminal portion of bactericidal/permeability-increasing protein, rBPI21, with various planar asymmetric and symmetric bilayer membranes, including the lipid matrix of the outer membrane of Gram-negative bacteria, were investigated via electrical measurements. For the lipopolysaccharide (LPS) leaflet of the outer membrane, isolated deep rough mutant LPS of Escherichia coli strain F515 (F515 LPS) and Proteus mirabilis strain R45 (R45 LPS) were used. The addition of rBPI21 to the LPS side of asymmetric LPS/phospholipid membranes, as well as to black lipid membranes made from dioleoylphosphatidylglycerol (DOPG), led to membrane rupture. The innermembrane potential difference resulted in a slight increase from 0 to 5 mV for symmetric DOPG membranes but changed for asymmetric F515 LPS/PL membranes from -36 to +8 mV and for R45 LPS/PL membranes from -37 to -5 mV following the addition of rBPI21. In all cases, the addition of rBPI21 led to an increase in membrane current. The effect of rBPI21 on the innermembrane potential difference of LPS/PL membranes was significantly reduced in the presence of 40 mM MgCl2 (shift from -36 to -31 mV for F515 LPS). On the basis of these results and from our studies on the interaction of rBPI21 with lipid monolayers and aggregates [Wiese, A., et al. (1997) Biochemistry 36, 10301-10310], a model is discussed explaining how the observed membrane rupture, increase of membrane current, and change of transmembrane potential as induced by rBPI21 may contribute to bacterial dysfunction.
通过电学测量研究了杀菌/通透性增加蛋白的重组N端部分（rBPI21）与各种平面不对称和对称双层膜（包括革兰氏阴性菌外膜的脂质基质）的相互作用机制。对于外膜的脂多糖（LPS）小叶，使用了大肠杆菌菌株F515的分离深粗糙突变体LPS（F515 LPS）和奇异变形杆菌菌株R45的LPS（R45 LPS）。将rBPI21添加到不对称LPS/磷脂膜的LPS侧以及由二油酰磷脂酰甘油（DOPG）制成的黑色脂质膜上，会导致膜破裂。对于对称的DOPG膜，内膜电位差从0略微增加到5 mV，但在添加rBPI21后，不对称的F515 LPS/PL膜从-36 mV变为+8 mV，R45 LPS/PL膜从-37 mV变为-5 mV。在所有情况下，添加rBPI21都会导致膜电流增加。在存在40 mM MgCl2的情况下，rBPI21对LPS/PL膜内膜电位差的影响显著降低（F515 LPS从-36 mV变为-31 mV）。基于这些结果以及我们对rBPI21与脂质单层和聚集体相互作用的研究[Wiese, A.,等人（1997年）《生物化学》36, 10301 - 10310]，讨论了一个模型，解释了rBPI21诱导的膜破裂、膜电流增加和跨膜电位变化如何可能导致细菌功能障碍。
