Basso Luis G Mansor, Mendes Luis F Santos, Costa-Filho Antonio J
Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
Biophys Rev. 2016 Jun;8(2):179-191. doi: 10.1007/s12551-016-0199-5. Epub 2016 Apr 30.
Protein-membrane interactions play essential roles in a variety of cell functions such as signaling, membrane trafficking, and transport. Membrane-recruited cytosolic proteins that interact transiently and interfacially with lipid bilayers perform several of those functions. Experimental techniques capable of probing changes on the structural dynamics of this weak association are surprisingly limited. Among such techniques, electron spin resonance (ESR) has the enormous advantage of providing valuable local information from both membrane and protein perspectives by using intrinsic paramagnetic probes in metalloproteins or by attaching nitroxide spin labels to proteins and lipids. In this review, we discuss the power of ESR to unravel relevant structural and functional details of lipid-peripheral membrane protein interactions with special emphasis on local changes of specific regions of the protein and/or the lipids. First, we show how ESR can be used to investigate the direct interaction between a protein and a particular lipid, illustrating the case of lipid binding into a hydrophobic pocket of chlorocatechol 1,2-dioxygenase, a non-heme iron enzyme responsible for catabolism of aromatic compounds that are industrially released in the environment. In the second case, we show the effects of GPI-anchored tissue-nonspecific alkaline phosphatase, a protein that plays a crucial role in skeletal mineralization, and on the ordering and dynamics of lipid acyl chains. Then, switching to the protein perspective, we analyze the interaction with model membranes of the brain fatty acid binding protein, the major actor in the reversible binding and transport of hydrophobic ligands such as long-chain, saturated, or unsaturated fatty acids. Finally, we conclude by discussing how both lipid and protein views can be associated to address a common question regarding the molecular mechanism by which dihydroorotate dehydrogenase, an essential enzyme for the de novo synthesis of pyrimidine nucleotides, and how it fishes out membrane-embedded quinones to perform its function.
蛋白质与膜的相互作用在多种细胞功能中发挥着重要作用，如信号传导、膜运输和物质转运。膜招募的胞质蛋白与脂质双层进行瞬时和界面相互作用，执行其中的一些功能。能够探测这种弱相互作用结构动力学变化的实验技术出奇地有限。在这些技术中，电子自旋共振（ESR）具有巨大优势，通过使用金属蛋白中的固有顺磁探针，或通过将氮氧化物自旋标记物连接到蛋白质和脂质上，从膜和蛋白质两个角度提供有价值的局部信息。在本综述中，我们讨论了ESR揭示脂质-外周膜蛋白相互作用相关结构和功能细节的能力，特别强调蛋白质和/或脂质特定区域的局部变化。首先，我们展示了ESR如何用于研究蛋白质与特定脂质之间的直接相互作用，以脂质结合到氯儿茶酚1,2-双加氧酶的疏水口袋为例，该酶是一种非血红素铁酶，负责分解环境中工业释放的芳香化合物。在第二个例子中，我们展示了糖基磷脂酰肌醇锚定的组织非特异性碱性磷酸酶的作用，该蛋白在骨骼矿化中起关键作用，以及对脂质酰链的有序性和动力学的影响。然后，从蛋白质的角度出发，我们分析了脑脂肪酸结合蛋白与模型膜的相互作用，脑脂肪酸结合蛋白是可逆结合和运输疏水配体（如长链、饱和或不饱和脂肪酸）的主要参与者。最后，我们通过讨论如何将脂质和蛋白质的观点结合起来，以解决一个关于二氢乳清酸脱氢酶（嘧啶核苷酸从头合成所必需的酶）的分子机制的共同问题，以及它如何捞出膜嵌入的醌来执行其功能来得出结论。
