Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria.
Sofia University "St. Kliment Ohridski", Department of Biochemistry, Faculty of Biology, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria.
Colloids Surf B Biointerfaces. 2018 Jan 1;161:192-199. doi: 10.1016/j.colsurfb.2017.10.051. Epub 2017 Oct 18.
Bestrophinopathies are ocular diseases caused by mutations in the human bestrophin-1 (hBest1) - transmembrane Ca-activated chloride channel protein, mainly expressed in the retinal pigment epithelium (RPE) cells. hBest1 is also an important transporter for neurotransmitters such as glutamate (Glu) and γ-aminobutyric acid (GABA) in the nervous system. Recently, a new biological role of hBest1, related to its possible involvement in the pathology of brain diseases (Alzheimer's, Parkinson's disease) has been proposed. Here, we report the effects of Ca, Glu and GABA on hBest1 and composite hBest1/POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) Langmuir and Langmuir-Blodgett monolayers based on surface dynamics (π/A isotherms, hysteresis and compressibility), morphology (Brewster angle microscopy, BAM) and visualization of protein molecular organization (Atomic force microscopy, AFM). Ca ions and neurotransmitters Glu and GABA affect hBest1 topology at the air/water interface altering its surface activity, size, orientation and organization. In contrast, no significant changes were detected on π/A isotherms and hysteresis of the composite hBest1/POPC films but their effects on structure, aggregation state and orientation hBest1 established by BAM and AFM differentiate. We found that the binary films of hBest1 and POPC are phase separated at the air/water interface, suggesting stronger lipid-lipid and protein-protein interactions than lipid-protein interactions that can significantly alter the molecular organization and activity of hBest1 in cell membranes. Our data shed light on structure, surface behavior and organization of hBest1 that define relationship structure-functional activity of hBest1 as transport channel.
Bestrophinopathies 是一种眼部疾病，由人类 bestrophin-1 (hBest1) - 跨膜 Ca 激活氯离子通道蛋白的突变引起，主要在视网膜色素上皮 (RPE) 细胞中表达。hBest1 也是神经系统中神经递质如谷氨酸 (Glu) 和 γ-氨基丁酸 (GABA) 的重要转运体。最近，hBest1 的一个新的生物学作用被提出，与它可能参与脑疾病 (阿尔茨海默病、帕金森病) 的病理学有关。在这里，我们报告了 Ca、Glu 和 GABA 对 hBest1 以及复合 hBest1/POPC (1-棕榈酰基-2-油酰基-sn-甘油-3-磷酸胆碱) Langmuir 和 Langmuir-Blodgett 单层膜的影响，基于表面动力学 (π/A 等温线、滞后和可压缩性)、形态 (Brewster 角显微镜，BAM) 和蛋白质分子组织可视化 (原子力显微镜，AFM)。Ca 离子和神经递质 Glu 和 GABA 会改变 hBest1 在气/水界面的拓扑结构，从而改变其表面活性、大小、取向和组织。相比之下，复合 hBest1/POPC 膜的 π/A 等温线和滞后没有明显变化，但 BAM 和 AFM 检测到的它们对 hBest1 结构、聚集状态和取向的影响不同。我们发现 hBest1 和 POPC 的二元膜在气/水界面上是分相的，这表明脂质-脂质和蛋白质-蛋白质之间的相互作用比脂质-蛋白质之间的相互作用更强，这可能显著改变细胞膜中 hBest1 的分子组织和活性。我们的数据阐明了 hBest1 的结构、表面行为和组织，这些定义了 hBest1 作为转运通道的结构-功能活性关系。
