DeWolf C, McCauley P, Sikorski A F, Winlove C P, Bailey A I, Kahana E, Pinder J C, Gratzer W B
Department of Chemical Engineering, Imperial College, London, England.
Biophys J. 1997 Jun;72(6):2599-604. doi: 10.1016/S0006-3495(97)78903-3.
The interaction with membrane lipids of recombinant fragments of human dystrophin, corresponding to a single structural repeating unit of the rod domain, was examined. Surface plasmon resonance, constant-pressure isotherms in a Langmuir surface film balance, and interfacial rheology were used to observe binding of the polypeptides and its effects on the properties of the lipid film. Modification of the monolayer properties was found to depend on the presence of phosphatidylserine in the lipid mixture and on the native tertiary fold of the polypeptide; thus a fragment with the minimum chain length required for folding (117 residues) or longer caused a contraction of the surface area at constant pressure, whereas fragments of 116 residues or less had no effect. The full extent of contraction was reached at a surface concentration of lipid corresponding to an average area of about 42 A2 per lipid molecule. A dystrophin fragment with the native, folded conformation induced a large increase in surface shear viscosity of the lipid film, whereas an unfolded fragment had no effect. Within a wide range of applied shear, the shear viscosity remained Newtonian. Binding of liposomes to immobilized dystrophin fragments could be observed by surface plasmon resonance and was again related to the conformational state of the polypeptide and the presence of phosphatidylserine in the liposomes. Our results render it likely that intact dystrophin interacts directly and strongly with the sarcolemmal lipid bilayer and grossly modifies its material properties.
研究了与人类肌营养不良蛋白重组片段的膜脂质相互作用，该片段对应于杆状结构域的单个结构重复单元。利用表面等离子体共振、Langmuir表面膜天平中的恒压等温线和界面流变学来观察多肽的结合及其对脂质膜性质的影响。发现单层性质的改变取决于脂质混合物中磷脂酰丝氨酸的存在以及多肽的天然三级结构；因此，具有折叠所需最小链长（117个残基）或更长的片段在恒压下会导致表面积收缩，而116个残基或更少的片段则没有影响。在对应于每个脂质分子平均面积约42 Å2的脂质表面浓度下达到了最大收缩程度。具有天然折叠构象的肌营养不良蛋白片段会导致脂质膜表面剪切粘度大幅增加，而未折叠的片段则没有影响。在广泛的施加剪切范围内，剪切粘度保持牛顿流体特性。通过表面等离子体共振可以观察到脂质体与固定化肌营养不良蛋白片段的结合，这同样与多肽的构象状态以及脂质体中磷脂酰丝氨酸的存在有关。我们的结果表明，完整的肌营养不良蛋白可能直接且强烈地与肌膜脂质双层相互作用，并极大地改变其材料特性。
