Glycerol conductance and physical asymmetry of the Escherichia coli glycerol facilitator GlpF
Glycerol conductance and physical asymmetry of the Escherichia coli glycerol facilitator GlpF
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DOI：
10.1016/s0006-3495(03)74718-3
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发表时间：
2003-11-01
影响因子：
3.4
通讯作者：
Schulten, K
中科院分区：
文献类型：
--
作者：
Lu, DY;Grayson, P;Schulten, K
水甘油孔蛋白 GlpF 是大肠杆菌的跨膜通道，有助于细胞摄取甘油。其高甘油摄取率对于细胞在极低甘油浓度下生存至关重要。尽管GlpF允许甘油流入和流出，但其结构与麦芽孔蛋白的结构相似，表现出显着程度的不对称性。通道中表征甘油的平均力的潜力显示出相应的不对称性，仅在周质侧具有有吸引力的前庭。在这项研究中，我们分析了平均力的潜力，表明简化的六步模型捕获了动力学并产生了与观察结果非常吻合的甘油传导率。在 10-muM 和 10-mM 周质甘油浓度下，前庭的传导率分别提高了 40% 和 75%。此外，单一甘油的传导速率和传导概率（效率）都不取决于 GlpF 的方向。 GlpF 在生理条件下似乎在两个方向上都表现得同样好。
The aquaglyceroporin GlpF is a transmembrane channel of Escherichia coli that facilitates the uptake of glycerol by the cell. Its high glycerol uptake rate is crucial for the cell to survive in very low glycerol concentrations. Although GlpF allows both influx and outflux of glycerol, its structure, similar to the structure of maltoporin, exhibits a significant degree of asymmetry. The potential of mean force characterizing glycerol in the channel shows a corresponding asymmetry with an attractive vestibule only at the periplasmic side. In this study, we analyze the potential of mean force, showing that a simplified six-step model captures the kinetics and yields a glycerol conduction rate that agrees well with observation. The vestibule improves the conduction rate by 40% and 75% at 10-muM and 10-mM periplasmic glycerol concentrations, respectively. In addition, neither the conduction rate nor the conduction probability for a single glycerol (efficiency) depends on the orientation of GlpF. GlpF appears to conduct equally well in both directions under physiological conditions.