Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands;
Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands; Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands; and.
FASEB J. 2014 Oct;28(10):4292-302. doi: 10.1096/fj.14-251579. Epub 2014 Jun 23.
One of the best-studied mechanosensitive channels is the mechanosensitive channel of large conductance (MscL). MscL senses tension in the membrane evoked by an osmotic down shock and directly couples it to large conformational changes leading to the opening of the channel. Spectroscopic techniques offer unique possibilities to monitor these conformational changes if it were possible to generate tension in the lipid bilayer, the native environment of MscL, during the measurements. To this end, asymmetric insertion of l-α-lysophosphatidylcholine (LPC) into the lipid bilayer has been effective; however, how LPC activates MscL is not fully understood. Here, the effects of LPC on tension-sensitive mutants of a bacterial MscL and on MscL homologs with different tension sensitivities are reported, leading to the conclusion that the mode of action of LPC is different from that of applied tension. Our results imply that LPC shifts the free energy of gating by interfering with MscL-membrane coupling. Furthermore, we demonstrate that the fine-tuned addition of LPC can be used for controlled activation of MscL in spectroscopic studies.
研究最为透彻的机械敏感性通道之一是大电导机械敏感性通道（MscL）。MscL 感应由渗透压冲击引起的膜张力，并将其直接与导致通道开放的大构象变化偶联。如果在测量过程中能够在 MscL 的天然环境——脂质双层中产生张力，光谱技术将提供监测这些构象变化的独特可能性。为此，已经证明不对称插入 l-α-溶血磷脂酰胆碱（LPC）到脂质双层中是有效的；然而，LPC 如何激活 MscL 还不完全清楚。在这里，报告了 LPC 对细菌 MscL 的张力敏感突变体和具有不同张力敏感性的 MscL 同源物的影响，得出的结论是，LPC 的作用模式与施加的张力不同。我们的结果表明，LPC 通过干扰 MscL-膜偶联来改变门控的自由能。此外，我们证明了精细添加的 LPC 可用于在光谱研究中对 MscL 进行受控激活。
